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  • 1
    Electronic Resource
    Electronic Resource
    Time-lapsed confocal microscopy reveals temporal and spatial expression of the lysine ɛ-aminotransferase gene in Streptomyces clavuligerus (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: To investigate the temporal and spatial expression patterns of the gene (lat ) encoding lysine ɛ-aminotransferase (LAT) for cephamycin C biosynthesis, a mutant form of green fluorescent protein (mut1GFP) was integrated into the Streptomyces clavuligerus chromosome (strain LH369), resulting in a translational fusion with lat. LAT activity and fluorescence profiles of the recombinant protein paralleled the native LAT enzyme activity profile in wild-type S. clavuligerus, which peaked during exponential growth phase and decreased slowly towards stationary phase. These results indicate that the LAT–Mut1GFP fusion protein retains both LAT and GFP functionality in S. clavuligerus LH369. LH369 produced wild-type levels of cephamycin C in minimal medium culture conditions supplemented with lysine. Time-lapsed confocal microscopy of the S. clavuligerus LH369 strain revealed the temporal and spatial characteristics of lat gene expression and demonstrated that physiological development of S. clavuligerus colonies leading to cephamycin C biosynthesis is limited to the substrate mycelia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01638.x
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  • 2
    Electronic Resource
    Electronic Resource
    An ordered reaction mechanism for bacterial toxin acylation by the specialized acyltransferase HlyC: formation of a ternary complex with acylACP and protoxin substrates (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The 110 kDa haemolysin protoxin (proHlyA) is activated in the Escherichia coli cytosol by acyl carrier protein-dependent fatty acylation of two internal lysine residues, directed by the co-synthesized protein HlyC. Using an in vitro maturation reaction containing purified protoxin peptides and acylACP, we show unambiguously that HlyC possesses an apparently unique acyltransferase activity fully described by Michaelis–Menten analysis. The Vmax of HlyC at saturating levels of both substrates was ≈ 115 nmol acyl group min−1 mg−1 with KmacylACP of 260 nM and KmproHlyA of 27 nM, kinetic parameters sufficient to explain why in vivo HlyC is required at a concentration equimolar to proHlyA. HlyC bound the fatty acyl group from acylACP to generate an acylated HlyC intermediate that was depleted in the presence of proHlyA, but enriched in the presence of proHlyA derivatives lacking acylation target sites. HlyC was also able to bind in vivo 4′-phosphopantetheine. Substitution of conserved amino acids that could act as putative covalent attachment sites did not prevent binding of the fatty acyl or 4′-phosphopantetheine groups. These data and substrate variation analyses suggest that the unique acylation reaction does not involve covalent attachment of fatty acid to the acyltransferase, but rather that it proceeds via a sequential ordered Bi–Bi reaction mechanism, requiring the formation of a non-covalent ternary acylACP–HlyC–proHlyA complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01648.x
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  • 3
    Electronic Resource
    Electronic Resource
    Identification of dipeptide repeats and a cell wall sorting signal in the fimbriae-associated adhesin, Fap1, of Streptococcus parasanguis (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Fap1, a fimbriae-associated protein, is involved in fimbriae assembly and adhesion of Streptococcus parasanguis FW213 (Wu et al., 1998). In this study, the sequence of the fap1 gene was resolved using a primer island transposition system. Sequence analysis indicated that fap1 was composed of 7659 nucleotides. The predicted Fap1 protein contains an unusually long signal sequence (50 amino acid residues), a cell wall sorting signal and two repeat regions. Repeat regions I and II have a similar dipeptide composition (E/V/I)S, composed of 28 and 1000 repeats respectively. The two regions combined accounted for 80% of the Fap1 coding region. The experimental amino acid composition and isoelectric point (pI) of Fap1 were similar to that predicted from the deduced Fap1 protein. Results of Northern analyses revealed that the fap1 open reading frame (ORF) was transcribed as a 7.8 kb monocistronic message. Insertional inactivation at the 3′ end, downstream of the fap1 ORF, did not affect Fap1, fimbrial expression or bacterial adhesion. Insertional inactivation of fap1 immediately upstream of the repeat region II abolished expression of Fap1 and fimbriae, and was concurrent with a diminution in adhesion of FW213. Inactivation of the cell wall sorting signal of fap1 also eliminated long fimbrial formation and reduced the ability of FW213 to bind to SHA. Fap1 was no longer anchored on the cell surface. Large quantities of truncated Fap1 were found in the growth medium instead. These results suggest that the fap1 ORF alone is sufficient to support Fap1 expression and adhesion, and demonstrate that anchorage of Fap1 on the cell surface is required for long fimbriae formation. These data further document the role of long fimbriae in adhesion of S. parasanguis FW213 to SHA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01670.x
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of the function of Escherichia coli poly(A) polymerase I in RNA metabolism (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: To help understand the role of polyadenylation in Escherichia coli RNA metabolism, we constructed an IPTG-inducible pcnB [poly(A) polymerase I, PAP I] containing plasmid that permitted us to vary poly(A) levels without affecting cell growth or viability. Increased polyadenylation led to a decrease in the half-life of total pulse-labelled RNA along with decreased half-lives of the rpsO, trxA, lpp and ompA transcripts. In contrast, the transcripts for rne (RNase E) and pnp (polynucleotide phosphorylase, PNPase), enzymes involved in mRNA decay, were stabilized. rnb (RNase II) and rnc (RNase III) transcript levels were unaffected in the presence of increased polyadenylation. Long-term overproduction of PAP I led to slower growth and irreversible cell death. Differential display analysis showed that new RNA species were being polyadenylated after PAP I induction, including the mature 3′-terminus of 23S rRNA, a site that was not tailed in wild-type cells. Quantitative reverse transcriptase–polymerase chain reaction (RT–PCR) demonstrated an almost 20-fold variation in the level of polyadenylation among three different transcripts and that PAP I accounted for between 94% and 98.6% of their poly(A) tails. Cloning and sequencing of cDNAs derived from lpp, 23S and 16S rRNA revealed that, during exponential growth, C and U residues were polymerized into poly(A) tails in a transcript-dependent manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01673.x
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  • 5
    Electronic Resource
    Electronic Resource
    Quorum sensing in Pseudomonas aeruginosa controls expression of catalase and superoxide dismutase genes and mediates biofilm susceptibility to hydrogen peroxide (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Quorum sensing (QS) governs the production of virulence factors and the architecture and sodium dodecyl sulphate (SDS) resistance of biofilm-grown Pseudomonas aeruginosa. P. aeruginosa QS requires two transcriptional activator proteins known as LasR and RhlR and their cognate autoinducers PAI-1 (N-(3-oxododecanoyl)-l-homoserine lactone) and PAI-2 (N-butyryl-l-homoserine lactone) respectively. This study provides evidence of QS control of genes essential for relieving oxidative stress. Mutants devoid of one or both autoinducers were more sensitive to hydrogen peroxide and phenazine methosulphate, and some PAI mutant strains also demonstrated decreased expression of two superoxide dismutases (SODs), Mn-SOD and Fe-SOD, and the major catalase, KatA. The expression of sodA (encoding Mn-SOD) was particularly dependent on PAI-1, whereas the influence of autoinducers on Fe-SOD and KatA levels was also apparent but not to the degree observed with Mn-SOD. β-Galactosidase reporter fusion results were in agreement with these findings. Also, the addition of both PAIs to suspensions of the PAI-1/2-deficient double mutant partially restored KatA activity, while the addition of PAI-1 only was sufficient for full restoration of Mn-SOD activity. In biofilm studies, catalase activity in wild-type bacteria was significantly reduced relative to planktonic bacteria; catalase activity in the PAI mutants was reduced even further and consistent with relative differences observed between each strain grown planktonically. While wild-type and mutant biofilms contained less catalase activity, they were more resistant to hydrogen peroxide treatment than their respective planktonic counterparts. Also, while catalase was implicated as an important factor in biofilm resistance to hydrogen peroxide insult, other unknown factors seemed potentially important, as PAI mutant biofilm sensitivity appeared not to be incrementally correlated to catalase levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01672.x
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  • 6
    Electronic Resource
    Electronic Resource
    Residual polyadenylation in poly(A) polymerase I (pcnB ) mutants of Escherichia coli does not result from the activity encoded by the f310 gene (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: As extracts of poly(A) polymerase I (PAP I) deficient strains of Escherichia coli appeared to contain considerable residual polyadenylating activity, efforts were undertaken to identify a second poly(A) polymerase. Recently, a gene (f310 ) encoding the putative second poly(A) polymerase was cloned and sequenced. Here we have tested the ability of the F310 protein to add poly(A) tails in vivo by measuring total poly(A) levels in both f310 mutants and strains that overproduce F310. In addition, we have visualized poly(A) tails and examined ColE1 plasmid copy number in various genetic backgrounds. We also carried out direct biochemical measurements of AMP incorporation, using cell extracts after amplification of F310. All the data obtained indicate that F310 is not a poly(A) polymerase. Although the presence of two potential ATP binding domains in the F310 protein may account for its apparent ATP binding activity, its true biochemical function remains to be identified. In addition, we show that the f310 gene is transcribed, almost exclusively, during stationary phase from a σs promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01674.x
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  • 7
    Electronic Resource
    Electronic Resource
    Extensive interplasmidic duplications change the virulence phenotype of the relapsing fever agent Borrelia turicatae (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The relapsing fever agent Borrelia turicatae has two antigenically distinct serotypes, A and B, which differ in their variable small proteins (Vsps) and in their degree of virulence and neurotropism in mice. Each Vsp gene (vspA or vspB) had an expression-linked copy that was unique to the serotype expressing it. This was located on one linear plasmid, which was defined by the upstream sequence. The archived copies of vspA and vspB were each located on different linear plasmids that were the same in both serotypes. In this feature, the mechanism of antigenic variation is similar to that of another relapsing fever agent, B. hermsii. However, in other features, the mechanisms of the two organisms differ. The expressed and archived loci for vspA and vspB of B. turicatae were near the centre of linear plasmids instead of near the telomeres. The vspA and vspB expression loci were duplicate copies of their respective silent loci: from the vsp itself to at least 13–14 kb downstream. Despite the extensive interplasmidic duplications and the internal position of the expression locus, the only detectable difference between serotypes A and B was in whether they expressed VspA or VspB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01675.x
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  • 8
    Electronic Resource
    Electronic Resource
    Ambient pH signal transduction in Aspergillus: completion of gene characterization (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01693.x
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  • 9
    Electronic Resource
    Electronic Resource
    A molecular switch in SecA protein couples ATP hydrolysis to protein translocation (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: SecA, the dimeric ATPase subunit of bacterial protein translocase, catalyses translocation during ATP-driven membrane cycling at SecYEG. We now show that the SecA protomer comprises two structural modules: the ATPase N-domain, containing the nucleotide binding sites NBD1 and NBD2, and the regulatory C-domain. The C-domain binds to the N-domain in each protomer and to the C-domain of another protomer to form SecA dimers. NBD1 is sufficient for single rounds of SecA ATP hydrolysis. Multiple ATP turnovers at NBD1 require both the NBD2 site acting in cis and a conserved C-domain sequence operating in trans. This intramolecular regulator of ATP hydrolysis (IRA) mediates N-/C-domain binding and acts as a molecular switch: it suppresses ATP hydrolysis in cytoplasmic SecA while it releases hydrolysis in SecY-bound SecA during translocation. We propose that the IRA switch couples ATP binding and hydrolysis to SecA membrane insertion/deinsertion and substrate translocation by controlling nucleotide-regulated relative motions between the N-domain and the C-domain. The IRA switch is a novel essential component of the protein translocation catalytic pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01686.x
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  • 10
    Electronic Resource
    Electronic Resource
    Expression of the Escherichia coli NRZ nitrate reductase is highly growth phase dependent and is controlled by RpoS, the alternative vegetative sigma factor (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In the absence of oxygen, many bacteria preferentially use nitrate as a terminal electron acceptor for anaerobic respiration. In Escherichia coli, there are two membrane-bound, differentially regulated nitrate reductases. While the physiological basis for this metabolic redundancy is not completely understood, during exponential growth, synthesis of NRA is greatly induced by anaerobiosis plus nitrate, whereas NRZ is expressed at a low level that is not influenced by anaerobiosis or nitrate. In the course of identifying genes controlled by the stationary phase regulatory factor RpoS (σs), we found that the expression of NRZ is induced during entry into stationary phase and highly dependent on this alternative sigma factor. Expression studies, using operon fusions and nitrate reductase assays, revealed that the NRZ operon is controlled mainly at the level of transcription and is induced 10-fold at the onset of stationary phase in rich media. Consistent with previous reports of RpoS expression, the RpoS dependency of NRZ in minimal media was very high (several hundredfold). We also observed a fivefold stationary phase induction of NRZ in an rpoS background, indicating that other regulatory factors, besides RpoS, are probably involved in transcriptional control of NRZ. The RpoS dependence of NRZ expression was confirmed by Northern analyses using RNA extracted from wild-type and rpoS− strains sampled in exponential and stationary phase. In toto, these data indicate that RpoS-mediated regulation of NRZ may be an important physiological adaptation that allows the cell to use nitrate under stress-associated conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01637.x
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  • 11
    Electronic Resource
    Electronic Resource
    Flagellar proteins and type III-exported virulence factors are the predominant proteins secreted into the culture media of Salmonella typhimurium (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We analysed all major proteins secreted into culture media from Salmonella typhimurium. Proteins in culture supernatants were collected by trichloroacetic acid precipitation, separated in SDS–polyacrylamide gels and analysed by amino acid sequencing. Wild-type strain SJW1103 cells typically gave rise to nine bands in SDS gels: 89, 67, 58, 52, 50, 42, 40, 35 and (sometimes) 28 kDa. A search of the sequences in the available databases revealed that they were either flagellar proteins or virulence factors. Six of them were flagella specific: FlgK or HAP1 (58 kDa), FliC or flagellin (52 kDa), FliD or HAP2 (50 kDa), FlgE or hook protein (42 kDa), FlgL or HAP3 (35 kDa) and FlgD or hook-cap protein (28 kDa). The other four bands were specific for virulence factors: SipA (89 kDa), SipB (67 kDa), SipC (42 kDa) and InvJ (40 kDa). The 42 kDa band was a mixture of FlgE and SipC. We also analysed secreted proteins from more than 30 flagellar mutants, and they were categorized into four groups according to their band patterns: wild type, mot type, polyhook type and master gene type. Virulence factors were constantly secreted at a higher level in all flagellar mutants except a Δmot (motAB deletion) mutant, in which the amounts were greatly reduced. A new morphological pathway of flagellar biogenesis including protein secretion is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01639.x
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  • 12
    Electronic Resource
    Electronic Resource
    The MET3 promoter: a new tool for Candida albicans molecular genetics (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A central technique used to investigate the role of a Candida albicans gene is to study the phenotype of a cell in which both copies of the gene have been deleted. To date, such investigations can only be undertaken if the gene is not essential. We describe the use of the Candida albicans MET3 promoter to express conditionally an essential gene, so that the consequences of depletion of the gene product may be investigated. The effects of environmental conditions on its expression were investigated, using GFP as a reporter gene. The promoter showed an ≈85-fold range of expression, according to the presence or absence of either methionine or cysteine in concentrations in excess of 1 mM. In the presence of either amino acid, expression was reduced to levels that were close to background. We used URA3 as a model to demonstrate that the MET3 promoter could control the expression of an essential gene, provided that a mixture of both methionine and cysteine was used to repress the promoter. We describe an expression vector that may be used to express any gene under the control of the MET3 promoter and a vector that may be used to disrupt a gene and simultaneously place an intact copy under the control of the MET3 promoter. During the course of these experiments, we discovered that directed integration into the RP10 locus gives a high frequency of transformation, providing a means to solve a long-standing problem in this field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01641.x
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  • 13
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    Electronic Resource
    Relationships between a new type IV secretion system and the icm/dot virulence system of Legionella pneumophila (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We describe here a Legionella pneumophila type IV secretion system that is distinct from the previously described icm/dot system. This type IV secretion system contains 11 genes (lvh ) homologous to genes of other type IV secretion systems, arranged in a similar manner. The lvh genes were found to be located on a DNA island with a GC content higher than the L. pneumophila chromosome. In contrast to the icm/dot system that was shown to be required for intracellular growth in HL-60-derived human macrophages and Acanthamoeba castellanii, the lvh system was found to be dispensable for intracellular growth in these two hosts. The lvh system was found to be partially required for RSF1010 conjugation, a process that was previously shown to be completely dependent on several icm/dot genes. However, results obtained from analysis of double mutants in the icm/dot genes and the lvh genes revealed that lvh genes can substitute for some components of the icm/dot system for RSF1010 conjugation, but not for intracellular growth. These results indicate that components of the icm/dot system and components of the lvh type IV secretion system are able to interact with one another.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01642.x
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  • 14
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    Electronic Resource
    Phosphorylation-induced dimerization of the FixJ receiver domain (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The ‘two-component’ transcriptional activator FixJ controls nitrogen fixation in Sinorhizobium meliloti. Phosphorylation of FixJ induces its dimerization, as evidenced by gel permeation chromatography and equilibrium sedimentation analysis. Phosphorylation-induced dimerization is an intrinsic property of the isolated receiver domain FixJN. Accordingly, chemical phosphorylation of both FixJ and FixJN are second-order reactions with respect to protein concentration. However, the second-order phosphorylation constant is 44-fold higher for FixJN than for FixJ. Therefore, the C-terminal transcriptional activator domain FixJC inhibits the chemical phosphorylation of the receiver domain FixJN. Conversely, FixJN has been shown previously to inhibit FixJC activity ≈ 40-fold, reflecting the interaction between FixJN and FixJC. Therefore, we propose that modulation of FixJ activity involves both its dimerization and the disruption of the interface between FixJN and FixJC, resulting in the opening of the protein structure. Alanine scanning mutagenesis of FixJN indicated that the FixJ~P dimerization interface involves Val-91 and Lys-95 in helix α4. Dimerization was required for high-affinity binding to fixK promoter DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01614.x
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  • 15
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    The phenolic vir gene inducer ferulic acid is O-demethylated by the VirH2 protein of an Agrobacterium tumefaciens Ti plasmid (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Some or possibly all Ti plasmids of Agrobacterium tumefaciens encode a bicistronic operon designated virH, which encodes two proteins, VirH1 and VirH2, that resemble a family of cytochrome P450-type monooxygenases. Expression of this operon is induced by a family of phenolic compounds that induce all other operons within the vir regulon. We hypothesized that either or both of these proteins might metabolize some or all of these phenolic compounds. We therefore tested induction of a vir promoter by a variety of phenolic compounds in isogenic strains that express or lack virH1 and virH2. Although some compounds were equally effective inducers regardless of the virH status, other compounds induced vir expression far more effectively in the virH mutant than in the virH-proficient host. For all tested compounds, VirH2 appeared to be solely responsible for this effect. One such compound, ferulic acid, was chosen for biochemical analysis. Ferulic acid was degraded by a VirH-proficient host but not by a VirH mutant. The wild-type strain released large amounts of a more hydrophilic compound into the cell supernatant. This compound was tested by mass spectroscopy, nuclear magnetic resonance and UV spectroscopy and found to consist of caffeic acid. This indicates that wild-type strains convert virtually all added ferulic acid to caffeic acid, and that VirH2 is essential for this O-demethylation reaction. Ferulic acid was far more toxic than caffeic acid to the wild-type strain, although the wild-type strain was more resistant to ferulic acid than was the virH mutant. Caffeic acid was slowly removed from the broth, suggesting further metabolic reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01617.x
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  • 16
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    PrfA, the transcriptional activator of virulence genes, is upregulated during interaction of Listeria monocytogenes with mammalian cells and in eukaryotic cell extracts (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Most virulence genes of Listeria monocytogenes are activated by the transcriptional regulator PrfA. Previous studies have shown that environmental parameters, such as temperature, pH, stress conditions and medium composition, affect the expression of PrfA and PrfA-dependent proteins. In this report, we demonstrate a threefold increase in PrfA protein synthesis during infection of mammalian cells, which correlates with the increased activity of the plcA promoter, the major prfA promoter. Increased PrfA synthesis begins when L. monocytogenes adheres to host cells. In addition, we show that the observed induction of PrfA during the interaction of L. monocytogenes with mammalian cells can be reproduced in vitro using total cell extracts. Our data suggest a role for host proteinase K-sensitive protein(s) in PrfA upregulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01621.x
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  • 17
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    Elevated levels of polyamines and trypanothione resulting from overexpression of the ornithine decarboxylase gene in arsenite-resistant Leishmania (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The levels of trypanothione, a glutathione–spermidine conjugate, are increased in the protozoan parasite Leishmania selected for resistance to the heavy metal arsenite. The levels of putrescine and spermidine were increased in resistant mutants. This increase is mediated by overexpression of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. Gene overexpression is generally mediated by gene amplification in Leishmania but, here, the mRNA and the enzymatic activity of ODC are increased without gene amplification. This RNA overexpression is stable when cells are grown in the absence of the drug and does not result from gene rearrangements or from an increased rate of RNA synthesis. Transient transfections suggest that mutations in the revertant cells contribute to these elevated levels of RNA. Stable transfection of the ODC gene increases the level of trypanothione, which can contribute to arsenite resistance. In addition to ODC overexpression, the gene for the ABC transporter PGPA is amplified in the mutants. The co-transfection of the ODC and PGPA genes confers resistance in a synergistic fashion in partial revertants, also suggesting that PGPA recognizes metals conjugated to trypanothione.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01634.x
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  • 18
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    Mutational analysis of the Pseudomonas syringae pv. tomato hrpA gene encoding Hrp pilus subunit (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Plant pathogenic Pseudomonas syringae strains harbour a type III secretion pathway suggested to be involved in the delivery of effector proteins from the bacteria into plant cells. During plant interaction, the bacteria apparently produce surface appendages, termed Hrp pili, that are indispensable for the secretion process. We have created an insertion mutation library, as well as deletion mutations to hrpA, the structural gene encoding Hrp pilin. Analysis of the mutants revealed gene regions important for hrpA expression, pilus assembly and pilus-dependent autoagglutination of the bacteria. The majority of insertions in the amino-terminal half of the pilin were tolerated without bacterial interaction with plants being affected, while the carboxy-terminus appeared to be needed for pilus assembly. Insertions in the 5′ non-translated region and the first codons within the open reading frame affected mRNA production or stability and abolished protein production.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01635.x
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    A trans-envelope protein complex needed for filamentous phage assembly and export (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Assembly and export of filamentous phage requires four non-capsid proteins: the outer membrane protein, pIV; the inner membrane proteins, pI and pXI; and a cytoplasmic host factor, thioredoxin. Chemical cross-linking of intact cells demonstrates a trans-membrane complex containing pI and pIV. Formation of the complex protects pI from proteolytic cleavage by an endogenous protease. This protection also requires pXI, which is identical to the C-terminal portion of pI. This indicates that pXI, which is required for phage assembly in its own right, is also part of the complex. This complex forms in the absence of any other phage proteins or the DNA substrate; hence, it represents the first preinitiation step of phage morphogenesis. On the basis of protease protection data, we propose that the preinitiation complex is converted to an initiation complex by binding phage DNA, thioredoxin and the initiating minor coat protein(s).
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    Hyperosmotic shock induces the σ32 and σE stress regulons of Escherichia coli (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The rise in the levels of σS that accompanies hyperosmotic shock plays an important role in Escherichia coli survival by increasing the transcription of genes involved in the synthesis and transport of osmoprotectants. To determine if other stress regulons collaborate with σS in dealing with high osmolality, we used single copy fusions of lacZ to representative promoters induced by protein misfolding in the cytoplasm (dnaK and ibp ), extracytoplasmic stress [P3rpoH and htrA(degP )] and cold shock (cspA). Both the σ32-dependent, dnaK and ibp, promoters, and the σE-dependent, P3rpoH and htrA, promoters were rapidly but transiently induced when mid-exponential phase cells were treated with 0.464 M sucrose. The cspA promoter, however, did not respond to the same treatment. Overproduction of the cytoplasmic domain of the σE anti-sigma factor, RseA, reduced the magnitude of osmotic induction in λφ(P3rpoH::lacZ ) lysogens, but had no effect on the activation of the dnaK and ibp promoters. Similarly, induction of the dnaK::lacZ and ibp::lacZ fusions was not altered in either rpoS or ompR genetic backgrounds. Osmotic upshift led to a twofold increase in the enzymatic activity of the λTLF247 rpoH::lacZ translational fusion whether or not the cells were treated with rifampicin, indicating that both heat shock and exposure to high osmolality trigger a transient increase in rpoH translation. Our results suggest that the σ32, σE and σS regulons closely co-operate in the managment of hyperosmotic stress. Induction of the σ32 and σE regulons appears to be an emergency response required to repair protein misfolding and facilitate the proper folding of proteins that are rapidly synthesized following loss of turgor, while providing a mechanism to increase the activity of σS, the primary stress factor in osmoadaptation.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01664.x
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    Interspecies complementation in Saccharopolyspora erythraea : elucidation of the function of oleP1, oleG1 and oleG2 from the oleandomycin biosynthetic gene cluster of Streptomyces antibioticus and generation of new erythromycin derivatives (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Two glycosyltransferase genes, oleG1 and oleG2, and a putative isomerase gene, oleP1, have previously been identified in the oleandomycin biosynthetic gene cluster of Streptomyces antibioticus. In order to identify which of these two glycosyltransferases encodes the desosaminyltransferase and which the oleandrosyltransferase, interspecies complementation has been carried out, using two mutant strains of Saccharopolyspora erythraea, one strain carrying an internal deletion in the eryCIII (desosaminyltransferase) gene and the other an internal deletion in the eryBV (mycarosyltransferase) gene. Expression of the oleG1 gene in the eryCIII deletion mutant restored the production of erythromycin A (although at a low level), demonstrating that oleG1 encodes the desosaminyltransferase required for the biosynthesis of oleandomycin and indicating that, as in erythromycin biosynthesis, the neutral sugar is transferred before the aminosugar onto the macrocyclic ring. Significantly, when an intact oleG2 gene (presumed to encode the oleandrosyltransferase) was expressed in the eryBV deletion mutant, antibiotic activity was also restored and, in addition to erythromycin A, new bioactive compounds were produced with a good yield. The neutral sugar residue present in these compounds was identified as l-rhamnose attached at position C-3 of an erythronolide B or a 6-deoxyerythronolide B lactone ring, thus indicating a relaxed specificity of the oleandrosyltransferase, OleG2, for both the activated sugar and the macrolactone substrate. The oleP1 gene located immediately upstream of oleG1 was likewise introduced into an eryCII deletion mutant of Sac. erythraea, and production of erythromycin A was again restored, demonstrating that the function of OleP1 is identical to that of EryCII in the biosynthesis of dTDP-d-desosamine, which we have previously proposed to be a dTDP-4-keto-6-deoxy-d-glucose 3,4-isomerase.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01666.x
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    Conservation of xer site-specific recombination genes in bacteria (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01668.x
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  • 23
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    Spontaneous tandem amplification and deletion of the Shiga toxin operon in Shigella dysenteriae 1 (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Only one species of Shigella, Shigella dysenteriae 1, has been demonstrated to produce Shiga toxin (Stx). Stx is closely related to the toxins produced by Shiga toxin-producing Escherichia coli (STEC). In STEC, these toxins are often encoded on lambdoid bacteriophages and are major virulence factors for these organisms. Although the bacteriophage-encoded stx genes of STEC are highly mobile, the stx genes in S. dysenteriae 1 have been believed to be chromosomally encoded and not transmissible. We have located the toxin genes of S. dysenteriae 1 to a region homologous to minute 30 of the E. coli chromosome, within a 22.4 kbp putative composite transposon bracketed by IS600 insertion sequences. This region is present in all the S. dysenteriae 1 strains examined. Tandem amplification occurs via the flanking insertion sequences, leading to increased toxin production. The global regulatory gene, fnr, is located within the stx region, allowing deletions of the toxin genes to be created by anaerobic growth on chlorate-containing medium. Deletions occur by recombination between the flanking IS600 elements. Lambdoid bacteriophage genes are found both upstream and within the region, and we demonstrate the lysogeny of Shigella species with STEC bacteriophages. These observations suggest that S. dysenteriae 1 originally carried a Stx-encoding lambdoid prophage, which became defective due to loss of bacteriophage sequences after IS element insertions and rearrangements. These insertion sequences have subsequently allowed the amplification and deletion of the stx region.
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    Interaction between the F plasmid TraA (F-pilin) and TraQ proteins (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Elaboration of conjugative (F) pili by F+ strains of Escherichia coli requires the activities of over a dozen F-encoded DNA transfer (Tra) proteins. The organization and functions of these proteins are largely unknown. Using the yeast two-hybrid assay, we have begun to analyse binary interactions among the Tra proteins required for F-pilus formation. We focus here on interactions involving F-pilin, the only known F-pilus subunit. Using a library of F tra DNA fragments that contained all the F genes required for F pilus formation in a yeast GAL4 activation domain vector (pACTII), we transformed yeast containing a plasmid (pAS1CYH2traA) encoding a GAL4 DNA-binding domain–F-pilin fusion. Doubly transformed cells were screened for GAL4-dependent gene expression. This screen repeatedly identified only a single Tra protein, TraQ, previously identified as a likely F-pilin chaperone. The F-pilin–TraQ interaction appeared to be specific, as no transcriptional activation was detected in yeast transformants containing pACTIItraQ plasmids and the Salmonella typhi pED208 traA gene cloned in pAS1CYH2. Two traQ segments isolated in the screen against F-pilin were tested for complementation of a traQ null allele in E. coli. One, lacking the first 11 (of 94) TraQ amino acids, restored DNA donor activity, donor-specific bacteriophage sensitivity and membrane F-pilin accumulation to wild-type levels. The second, lacking the first 21 amino acids, was much less effective in these assays. Both TraQ polypeptides accumulated in E. coli as transmembrane proteins. The longer, biologically active segment was fused to the GAL4 DNA-binding domain gene of pAS1CYH2 and used to screen the tra fragment library. The only positives from this screen identified traA segments. The fusion sites between the traA and GAL4 segments identified the hydrophobic, C-terminal domain IV of F-pilin as sufficient for the interaction. As TraQ is the only Tra protein required for the accumulation of inner membrane F-pilin, the interaction probably reflects a specific, chaperone-like function for TraQ in E. coli. Attempts to isolate an F-pilin–TraQ complex from E. coli were unsuccessful, suggesting that the interaction between the two is normally transient, as expected from previous studies of the kinetics of TraA membrane insertion and processing to F-pilin.
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    Histidine kinases: diversity of domain organization (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
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    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Histidine kinases play a major role in signal transduction in prokaryotes for the cellular adaptation to environmental conditions and stresses. Recent progress in the three-dimensional structure determination of two representative members of histidine kinases, EnvZ (class I) and CheA (class II), has revealed common structural features, as well as a kinase catalytic motif topologically similar to those of the ATP-binding domains of a few ATPases. They have also disclosed that there are significant differences in domain organization between class I and II histidine kinases, possibly reflecting their distinct locations, functions and regulatory mechanisms. In spite of this diversity, both class I and II histidine kinases use similar four-helix bundle motifs to relay phosphoryl groups from ATP to regulatory domains of response regulators. The previously known so-called transmitter domain of histidine kinase is further dissected into two domains: a CA (Catalytic ATP-binding) domain and a DHp (Dimerization Histidine phosphotransfer) domain for class I, or a CA domain and an HPt (Histidine-containing Phosphotransfer) domain for class II histidine kinases. From a comparative analysis of the CA domains of EnvZ, CheA and their ATPase homologues, the core elements of the CA domain have been derived. The apparent resemblance between DHp and HPt domains is only superficial, and significant differences between them are discussed.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01646.x
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    Activation of the cycA P2 promoter for the Rhodobacter sphaeroides cytochrome c2 gene by the photosynthesis response regulator (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Rhodobacter sphaeroides photosynthesis response regulator, PrrA, positively regulates cycA P2 expression. Deletion analysis has identified sequences within 73 bp upstream of the transcription initiation site that are required for the activation of cycA P2 by PrrA. A mutant form of the Rhodobacter capsulatus PrrA homologue, whose activity is independent of phosphorylation (RegA*), protects an ≈ 26 bp region of cycA P2 that is centred at ≈ −50 from DNase digestion, and activates transcription of a mutant −14T promoter with increased activity when using either R. sphaeroides RNA polymerase or Escherichia coli Eσ70. A 4 bp target site mutation that eliminated DNA binding and transcription activation by RegA*in vitro also abolished PrrA activation of cycA P2 transcription in vivo, indicating that this region contains a PrrA binding site. By analysing the behaviour of the −14T mutant cycA P2 promoter in vivo, we also found that PrrA uses the same target site to activate expression in both the presence and the absence of O2. However, the extent of transcription activation by PrrA at cycA P2 in vivo is greater under anaerobic conditions.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01649.x
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  • 27
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    Testing the ‘+2 rule’ for lipoprotein sorting in the Escherichia coli cell envelope with a new genetic selection (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We report a novel strategy for selecting mutations that mislocalize lipoproteins within the Escherichia coli cell envelope and describe the mutants obtained. A strain carrying a deletion of the chromosomal malE gene, coding for the periplasmic maltose-binding protein (MalE), cannot use maltose unless a wild-type copy of malE is present in trans. Replacement of the natural signal peptide of preMalE by the signal peptide and the first four amino acids of a cytoplasmic membrane-anchored lipoprotein resulted in N-terminal fatty acylation of MalE (lipoMalE) and anchoring to the periplasmic face of the cytoplasmic membrane, where it could still function. When the aspartate at position +2 of this protein was replaced by a serine, lipoMalE was sorted to the outer membrane, where it could not function. Chemical mutagenesis followed by selection for maltose-using mutants resulted in the identification of two classes of mutations. The single class I mutant carried a plasmid-borne mutation that replaced the serine at position +2 by phenylalanine. Systematic substitutions of the amino acid at position +2 revealed that, besides phenylalanine, tryptophan, tyrosine, glycine and proline could all replace classical cytoplasmic membrane lipoprotein sorting signal (aspartate +2). Analysis of known and putative lipoproteins encoded by the E. coli K-12 genome indicated that these amino acids are rarely found at position +2. In the class II mutants, a chromosomal mutation caused small and variable amounts of lipoMalE to remain associated with the cytoplasmic membrane. Similar amounts of another, endogenous outer membrane lipoprotein, NlpD, were also present in the cytoplasmic membrane in these mutants, indicating a minor, general defect in the sorting of outer membrane lipoproteins. Four representative class II mutants analysed were shown not to carry mutations in the lolA or lolB genes, known to be involved in the sorting of lipoproteins to the outer membrane.
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  • 28
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    Functional importance of regions in Escherichia coli elongation factor NusA that interact with RNA polymerase, the bacteriophage λ N protein and RNA (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The association of the essential Escherichia coli protein NusA with RNA polymerase increases pausing and the efficiency of termination at intrinsic terminators. NusA is also part of the phage λ N protein-modified antitermination complex that functions to prevent transcriptional termination. We have investigated the structure of NusA using various deletion fragments of NusA in a variety of in vitro assays. Sequence and structural alignments have suggested that NusA has both S1 and KH homology regions that are thought to bind RNA. We show here that the portion of NusA containing the S1 and KH homology regions is important for NusA to enhance both termination and antitermination. There are two RNA polymerase-binding regions in NusA, one in the amino-terminal 137 amino acids and the other in the carboxy-terminal 264 amino acids; only the amino-terminal RNA polymerase-binding region provides a functional contact that enhances termination at an intrinsic terminator or antitermination by N. The carboxy-terminal region of NusA is also required for interaction with N and is important for the formation of an N–NusA–nut site or N–NusA–RNA polymerase–nut site complex; the instability of complexes lacking this carboxy-terminal region of NusA that binds N and RNA polymerase can be compensated for by the presence of the additional E. coli elongation factors, NusB, NusG and ribosomal protein S10.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01618.x
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  • 29
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    Positive co-regulation of the Escherichia coli carnitine pathway cai and fix operons by CRP and the CaiF activator (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Activation of the two divergent Escherichia coli cai and fix operons involved in anaerobic carnitine metabolism is co-dependent on the cyclic AMP receptor protein (CRP) and on CaiF, the specific carnitine-sensitive transcriptional regulator. CaiF was overproduced using a phage T7 system, purified on a heparin column and ran as a 15 kDa protein on SDS–PAGE. DNase I footprinting and interference experiments identified two sites, F1 and F2, with apparently comparable affinities for the binding of CaiF in the cai–fix regulatory region. These sites share a common perfect inverted repeat comprising two 11 bp half-sites separated by 13 bp, and centred at −70 and −127 from the fix transcription start site. They were found to overlap the two low-affinity binding sites, CRP2 and CRP3, determined previously for CRP. Gel shift assays and footprinting experiments suggest that CaiF and CRP bind co-operatively to the F1/CRP2 and F2/CRP3 sites of the intergenic cai–fix region. Moreover, they appeared to serve the simultaneous binding of each other, giving rise to an original multiprotein CRP–CaiF complex enabling RNA polymerase recruitment and local DNA untwisting, at least at the fix promoter. Using random mutagenesis, two CaiF mutants impaired in transcription activation were isolated. The N-terminal A27V mutation affected the structural organization of the activator, whereas the central I62N mutation was suggested to interfere with DNA binding.
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    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01622.x
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    Tropical Mariculture (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00331.x
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    Effect of processing soybean meal on the apparent digestibility of practical diets for the greenback flounder Rhombosolea tapirina (Günther) (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00367.x
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    Dominance hierarchy formation in Arctic charr Salvelinus alpinus (L.): nutrient digestibility of subordinate and dominant fish (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Arctic charr Salvelinus alpinus (L.) were individually tagged and maintained in circular tanks for 102 days in order to allow the development of dominance hierarchies. At the end of the trial period, the charr were anaesthetized in benzocaine and identified as dominant, beta (β) and subordinate according to a set of established criteria including size, coloration and bite marks. The gut contents were then collected and analysed for apparent digestibility coefficient of nutrients using the chromic oxide method. Subordinate fish had significantly lower specific growth rates and apparent nutrient digestibility coefficients of both dry matter and lipid compared with dominant fish. Although specific growth rate was significantly lower in the β fish compared with dominant charr, this did not influence the apparent digestibility coefficient of nutrients to any major extent.
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    The effects of cypermethrin (Excis) and azamethiphos (Salmosan) on lobster Homarus americanus H. Milne Edwards larvae in a laboratory study (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This research assessed the effects of two chemicals, cypermethrin (Excis) and azamethiphos (Salmosan), used in the treatment of sea lice Lepeophtheirus salmonis (Kroyer) on American lobster Homarus americanus H. Milne Edwards larvae under laboratory conditions. Larvae were exposed to concentrations of 5, 0.5, 0.05, 0.005 and 0 p.p.b. cypermethrin and 100, 10, 1, 0.1 and 0 p.p.b. azamethiphos for durations of 5, 30 and 60 min, 6 and 12 h in artificial seawater. Both treatment chemicals caused significant mortality (P 〈 0.05) of the lobster larvae below the recommended treatment doses of 5 p.p.b. cypermethrin for 1 h and 100 p.p.b. azamethiphos for 1 h. Temperature affected mortality significantly (P 〈 0.05). and interactions between treatment duration and treatment concentration were also significant (P 〈 0.05). LC50 values calculated for the treatment durations ranged from 0.66 to 0.058 p.p.b. at 10 °C and 1.69–0.365 p.p.b. at 12 °C for cypermethrin, and 33.9–1.3 p.p.b. at 10 °C and 50.4–0.9 p.p.b. at 12 °C for azamethiphos treatment, at the above treatment durations. The lowest LC50 values correspond to ≈ 1/90th of the recommended treatment dose for cypermethrin (Excis) at 12 °C and 1/14th at 10 °C; and 1/110th of the recommended treatment dose for azamethiphos (Salmosan) at 12 °C and 1/75th at 10 °C. The research determined variations in observed behavioural treatment effects on lobster larvae exposed to both cypermethrin and azamethiphos (temperature × treatment duration × treatment concentration; cypermethrin P 〈 0.001, azamethiphos P = 0.008). The pattern of effects that occurred at each temperature were, however, similar (cypermethrin P = 0.764; azamethiphos P = 0.218), and ‘intensity of effect’ of the treatment chemicals was positively correlated with an increasing treatment concentration high (r2 = 0.915, r2 = 0.905).
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00372.x
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    Maternal and cage effects on genetic parameter estimation for Pacific white shrimp Penaeus vannamei Boone (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Three sets of full-sib families of Pacific white shrimp Penaeus vannamei Boone, produced from females in different reproductive condition (15, 45 and 75 days after ablation and start of production), were used to estimate heritabilities and genetic correlations of growth traits for several larval and grow-out stages of development. Heritabilities for early larval length (nauplii) were larger when estimated from families produced 45 and 75 days after ablation than when estimated from families produced 15 days after ablation, indicating a maternal effect caused by lower reproductive quality of the females used to produce the second and third sets. However, the better reproductive quality of females used to produce the first set resulted in significant density effects on larval length, presumably caused by different mortalities occurring among families during larval culture, which also resulted in an increase in the heritability values estimated for late post-larvae stages. After transfer to grow-out cages in a pond, all estimated heritabilities decreased initially, then increased again. The increase in heritabilities was associated with a negative correlation between growth and density in the cages at 58 days. Lowering densities at this age resulted in a decrease in heritability values at 97 days, but an increase again thereafter. The largest genetic correlation with abdominal weight, the trait of most interest for improvement in shrimp, was total weight. That was followed by cephalothorax weight, width of first abdominal segment, abdominal length and total length. Among these, the trait with a consistently large heritability at 58 and 97 days, and with a large genetic correlation with abdominal weight, was width of first abdominal segment. This trait might provide a secondary or indirect trait to improve abdominal weight when combined with total weight for a selection programme.
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    Cultivation of the spotted wolffish Anarhichas minor (Olafsen) – a new candidate for cold-water fish farming (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The spotted wolffish Anarhichas minor (Olafsen), with its rich and tasty fillets, popular skin and high growth rates in captivity, is a promising candidate for cold-water aquaculture. We have established a production line for the wolffish during 5 years of active research on the biology of the species. Our broodstock, sampled from the Barents Sea, has mainly spawned during autumn. The females must be stripped as soon as possible after ovulation. The best egg batches have shown c. 100% fertilization and survival rates between 60% and 80% during the 800- to 960-daydegrees-long incubation period. Rearing temperatures of 6 °C, 8 °C, ambient and decreasing temperatures have turned out to be satisfactory for survival. Treatment with 150 p.p.m. glutardialdehyde twice a month is recommended to control microorganism growth on eggs. Premature hatching has been a problem in individual egg batches; the reasons are not fully understood. Normally hatched individuals are ≈ 22 mm long and well developed, with a small yolk sac, which is completely resorbed after about 4 weeks at 6–8 °C. The fry have been successfully start fed on formulated feed as well as Artemia. Highest early growth rates have been noted at 8 °C, but overall survival was best at 6 °C. On-growth of spotted wolffish juveniles fed formulated dry floating feed at low temperatures in shallow raceways has been promising. After 2, 3 and 4 years, the mean weights of the first generation produced in aquaculture were 0.7, 2.7 and 5.1 kg respectively. These individuals now make up the broodstock at a recently established commercial production facility.
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    Hybridization of Mediterranean groupers: Epinephelus marginatus♀×E. aeneus♂ and early development (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00365.x
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    Effects of different feeding regimes on growth, survival and feed conversion of hatchery-reared juveniles of the gastropod mollusc spotted babylon Babylonia areolata (Link 1807) in flowthrough culture systems (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of feeding regimes on the growth, survival and feed conversion of hatchery-reared juvenile spotted babylon Babylonia areolata (Link) were assessed. Six continuous and discontinuous feeding regimes were fed at satiation to triplicate groups of snails in 200-L flowthrough (3.0 L h–1) indoor rectangular tanks for 180 days. Shell length growth rates of juvenile B. areolata did not differ significantly (P 〉 0.05) between the various feeding treatments. Body weight gain and feed conversion of snails were not significantly different between various feeding treatments, nor were there significant differences in mean survival between any of the feeding treatments.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00366.x
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    Evaluation of juvenile silver perch Bidyanus bidyanus (Mitchell) nutritional needs using high- and low-protein diets at two feeding levels (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Juvenile silver perch Bidyanus bidyanus (Mitchell) of 3.2 g average weight were reared under controlled conditions on diets containing 23.4% and 40.6% protein. Diets were administered at 3% or 6% of the fish biomass per day. Both the protein concentrations and the feeding level of the diet influenced growth and proximate composition of the fish at the end of the 100-day growth trial. The energy requirement for these fish for maintenance was found to be 81.9 kcal × BW–0.8 and, for each unit of energy retained per metabolic body weight, 7.05 needed to be supplied, whereas for each gram of protein retained per metabolic body weight, 5.79 g were required. The results indicate that it is possible to obtain the same weight increment when feeding a 23.4% protein diet at a level of 6% body mass day–1 compared with only 3% body mass day–1 of a 40.6% protein diet. This study provides the first estimation of nutrient requirements for juvenile silver perch, and these estimations require further refinement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00376.x
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    The lipostat, hyperphagia and catch-up growth (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The hypothesis that long-term energy intake is matched to energy expenditure arose during the 1950s, and this formed the basis of the lipostatic model for the control of food intake in mammals. This gave rise to an additional hypothesis that body weight varies little over adult life because body fat, a variable related to body mass, is regulated. There is now a large body of evidence that adipose tissue plays a role in the regulation of feeding and body weight in mammals, and the study of the mechanisms by which the brain monitors the signals arising from the adipose tissue is currently a major area of research. After a period of nutritional restriction, a number of compensatory responses are invoked, and these result in hyperphagia, rapid weight increase and the repletion of energy reserves. However, the extent to which animals recover lost body weight has been reported to vary between studies. It is hypothesized that the rate at which animals replete their lipid reserves during catch-up growth may influence the hyperphagic response and, hence, whether or not there is complete recovery of body weight. Preliminary tests carried out using some data collected in studies of catch-up growth in salmonids appear to provide support for the model, but more experimental studies are needed to provide rigorous testing.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00358.x
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    Diel feeding rhythms of greenback flounder Rhombosolea tapirina (Günther 1862): the role of light–dark cycles and food deprivation (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The role of light–dark (LD) cycles and food deprivation in the regulation of diel feeding rhythms in greenback flounder Rhombosolea tapirina (Günther 1862) was examined. A computerized monitoring system was developed to record uneaten pellets, and food intake was estimated as the difference between pellets presented and those uneaten. Three groups of five fish each (75–281 g) were exposed sequentially to the LD cycles: LD 12:12, LD 12:12 (scotophase advanced by 9 h), LD 6:18, DD, LD 6:6:6:6, LL and LD 12:12 (return to the initial cycle). Illumination was 120 lux at the water surface (complete darkness at scotophase), and water temperature was 15 ± 1 °C. Fish fed mainly during the light hours under LD 12:12 and resynchronized to the scotophase-advanced LD 12:12 regime after about 12 h. Feeding started at the onset of light and extended to the early scotophase under LD 6:18. A circadian feeding rhythm was detected in fish under DD and LD 6:6:6:6 regimes. Under the LL regime, two groups of fish displayed arrhythmic feeding patterns and did not resynchronize to LD 12:12 for at least 13 days. In contrast, the third group of fish exhibited a circadian feeding rhythm under the LL regime and immediately re-entrained to LD 12:12. Fish were deprived of food for a single period of 26–57 h once feeding patterns had been established under LD 12:12, LD 12 : 12 (scotophase advanced by 9 h) and DD regimes, and feed delivery was resumed during the scotophase or subjective night; the timing of feeding rhythms was shifted by the reintroduction of feed, but progressively resynchronized to the LD cycles. The results suggest that the greenback flounder is a diurnal feeder, that a LD 12:12 cycle is a potent environmental cue to entrain circadian feeding rhythms, and that a biological clock is involved in the timing of feeding.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00373.x
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    Survival and growth of juvenile lobster Homarus gammarus L. raised for stock enhancement within in situ cages (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The growth of juvenile lobster Homarus gammarus L. reared on sandy sediments under laboratory conditions was compared with the growth of lobsters reared within in situ cages in the wild. The caged lobsters, left without any attention or care for 3 months, achieved an average size similar to that attained under optimal laboratory conditions. (8.8 mm carapace length; CL). Growth was positively correlated to cage size and depth. Overall average survival was 66%, ranging from 0% to 90% for clusters of 30 individually caged juveniles.
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    Genotyping of individual fish oocytes based on polymerase chain reaction amplification of mitochondrial DNA (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00347.x
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    Determining sediment properties around a marine cage farm using acoustic ground discrimination: RoxAnnTM (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Sediment traps collected significant quantities of waste solids beneath marine fish cages at a fish farm site in Greece. Diver observation and the absence of dissolved hydrogen sulphide in the water overlying sediments revealed low benthic impacts despite the very low current speeds measured. An acoustic bottom discrimination system, ground-truthed by conventional remote photography, further confirmed the apparently low benthic impact at this site. These results may be explained partly by the large number of fish present around the cages feeding on farm wastes.
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    Survival of amarillo snapper Lutjanus argentiventris (Peters 1869) at different salinities in captivity (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00352.x
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    High allozyme variation and genetic similarity of two populations of commercial penaeids, Penaeus brevirostris (Kingsley) and P. vannamei (Boone), from the Gulf of California (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Genetic resources assessment is considered as the starting point for population management in both fisheries and aquaculture. In this study, we have obtained genetic variability measures of two commercial penaeid shrimp species, Penaeus brevirostris (Kingsley) and P. vannamei (Boone), from the Gulf of California by means of starch electrophoresis analysis of 16 enzymatic systems, plus total protein. Thirty-two loci were resolved, which revealed polymorphism values (P95) of 15.63% in P. brevirostris and 25.00% in P. vannamei. Unbiased expected heterozygosity (He) was 0.076 and 0.105 respectively. These are high genetic variability figures, taking into account the previously low genetic variability, assessed by means of allozyme variation, reported in several penaeid species around the world. Nei’s genetic similarity between the two species is 0.891.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00354.x
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    The effect of transportation on the juvenile scallop Pecten maximus (L.) (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: At the present time, there is little information concerning the effect of transport on the physiology of scallops. Therefore, the overall objective of this study was to use the adenylic energetic charge (AEC) as an indicator of stress in scallops. Three transport trials were carried out: dry transport in polystyrene boxes containing seaweed and transport by vivier lorry at various densities. Post-transport scallop mortality was low for all trials, but the AEC results showed that scallop stress was reduced when animals were transported by vivier truck compared with dry transport. AEC levels in scallops remained high after 24.75 h of vivier transport in trial 2 (0.54–0.69) and after 17 h of vivier transport in trial 3 (0.79–0.82), whereas after 12 h of dry transport in trial 1, AEC levels in the striated muscle had decreased to 0.42. Ammonia concentration increased throughout the trials but did not appear to affect scallop survival in the short term. In general, the results indicate that greater survival can be achieved over longer distances (greater than 17 h) and at higher densities by vivier truck. However, better stability of holding units within tanks and a method to regulate ammonia and pH levels are needed if greater densities are used.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00332.x
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    Growth, metamorphosis and feeding behaviour of Rana catesbeiana Shaw 1802 tadpoles at different rearing densities (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: An experiment was carried out to investigate the effects of rearing density on growth, metamorphosis and behavioural patterns of feeding in bullfrog, Rana catesbeiana Shaw, tadpoles. Stage 25 (Gosner) tadpoles from a single cohort were stocked at 0.5, 1.0, 2.0, 4.0 and 8.0 L–1 in 6-L plastic containers. A combination of phytoplankton and supplementary feed was used. There was an inverse relationship between rearing density and growth and metamorphosis above two organisms L–1. Tadpoles reared at 0.5 and 1.0 L–1 reached the metamorphic climax in 135 and 120 days, respectively, whereas more than 80% of all tadpoles reared at 4 and 8 L–1 did not metamorphose at all. Intraspecific competition appeared to be consistent among the cultured organisms regardless of the rearing density. Smaller tadpoles were displaced to sites distant from feeding points during supplementary feed addition, while no displacement was observed during phytoplankton addition. It is concluded that bullfrog tadpoles grow well at up to two organisms L–1 and that intraspecific competition is present within cultured tadpoles regardless of stocking density and may result from intrinsic genetic variability.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00335.x
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    Evaluation of AQUI-STM (efficacy and minimum toxic concentration) as a fish anaesthetic/sedative for public aquaculture in the United States (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A preliminary evaluation of efficacy and minimum toxic concentration of AQUI-STM, a fish anaesthetic/sedative, was determined in two size classes of six species of fish important to US public aquaculture (bluegill, channel catfish, lake trout, rainbow trout, walleye and yellow perch). In addition, efficacy and minimum toxic concentration were determined in juvenile–young adult (fish aged 1 year or older) rainbow trout acclimated to water at 7°C, 12°C and 17°C. Testing concentrations were based on determinations made with range-finding studies for both efficacy and minimum toxic concentration. Most of the tested juvenile–young adult fish species were induced in 3 min or less at a nominal AQUI-STM concentration of 20 mg L–1. In juvenile–young adult fish, the minimum toxic concentration was at least 2.5 times the selected efficacious concentration. Three out of five species of fry–fingerlings (1.25–12.5 cm in length and 〈 1 year old) were induced in ≤ 4.1 min at a nominal concentration of 20 mg L–1 AQUI-STM, with the other two species requiring nominal concentrations of 25 and 35 mg L–1 for similar times of induction. Recovery times were ≤ 7.3 min for all species in the two size classes. In fry–fingerlings, the minimum toxic concentration was at least 1.4 times the selected efficacious concentration. There appeared to be little relationship between size of fish and concentrations or times to induction, recovery times and minimum toxic concentration. The times required for induction and for recovery were increased in rainbow trout as the acclimation temperature was reduced.
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    Assessment of Pacific oyster, Crassostrea gigas (Thunberg), size and quality using a computer-based shape analysis technique (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00319.x
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    Dominance hierarchies in Arctic charr, Salvelinus alpinus L.: differential cortisol profiles of dominant and subordinate individuals after handling stress (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: We examined the effect of social rank on plasma cortisol dynamics after handling stress in juvenile Arctic charr, Salvelinus alpinus L., reared in groups of 200 individuals in 1.5 m3 circular tanks (rearing density 0.022 kg L–1). Fish obtained by dip-netting were categorized as either socially subordinate, dominant or as holding an intermediate position on the basis of size, skin coloration and occurrence of bite marks. In undisturbed fish, the highest cortisol levels were found in fish ranked as intermediate and the lowest in dominant fish. In contrast to what has been found under conditions of artificial rearing in small groups (two to ten individuals), cortisol was not significantly elevated in subordinates compared with dominant individuals. In small groups of fish, aggressive interactions and restricted access to food may be significant factors leading to increased stress in socially subordinate individuals. Following stress by dip-netting and transfer, the quickest and largest cortisol response was seen in dominant individuals. These results suggest that hypothalamus–pituitary–inter-renal/adrenal axis responsiveness as well as baseline cortisol production is influenced by social rank in fish, as has been shown in other vertebrates.
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    The combined effects of temperature and salinity on embryos and larvae of the black-lip pearl oyster, Pinctada margaritifera (L.) (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This paper reports on a 4 × 4 factorial design experiment conducted to examine the combined effects of temperature and salinity on embryonic development and growth and survival of black-lip pearl oyster, Pinctada margaritifera (L.) larvae. The temperatures used were 20 °C, 25 °C, 30 °C and 35 °C, and the salinities were 25°/oo, 30°/oo, 35°/oo and 40°/oo. Response surface contour diagrams were generated from the survival and growth data to estimate optimal conditions. Normal development of embryos occurred only from 25 °C to 30 °C. The optimal conditions for maximum survival and growth were 26–29 °C and 28–32°/oo. Temperatures of 35 °C or greater were lethal for larvae and, at all temperatures tested, larval growth and survival were lowest at a salinity of 40°/oo.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00324.x
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    Non-specific immunity parameters and the formation of advanced glycosylation end-products (AGE) in rainbow trout, Oncorhynchus mykiss (Walbaum), fed high levels of dietary carbohydrates (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of long-term hyperglycaemia (5 months), through feeding high levels of dietary carbohydrates, on the non-specific immunity parameters of rainbow trout, Oncorhynchus mykiss (Walbaum), was assessed. Fish were fed one of three diets composed of a basal diet containing ≈ 14% digestible carbohydrate which was progressively diluted with gelatinized potato starch in the following ratios of basal diet to supplemental carbohydrate (gelatinized potato starch): 65:00, 65:20, 65:35. The three diets were pair-fed based on the feed intake of the fish fed the diet containing the highest level of starch (65:35) and representing 100% intake. The other diets were then fed at different levels in a manner that allowed all the groups of fish in the same block to receive the same amount of the basal diet [e.g. the basal diet (undiluted, 65:00) was fed at 65% of the dietary intake of the 65:35 diet]. Blood glucose concentrations and relative liver-to-body size increased with increased dietary carbohydrate intake. Feeding supplemental carbohydrates resulted in a small increase in weight gain of the fish at both supplemental levels. Pronephros tissue lysozyme activity and pronephros macrophage superoxide production were not affected by the dietary treatments. The results suggest the presence of advanced glycosylation end-products in muscle tissue collagen, but were not significantly different between treatments. No substantial effect of long-term feeding of a high carbohydrate diet on the non-specific immunity of rainbow trout was observed. However, the results suggest that dietary carbohydrates may have a slight stimulatory effect on phagocytosis at low–moderate levels.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00330.x
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    Culture of the microalgae Chaetoceros muelleri with Zecer-56, a natural zeolitic product (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Zeolitic products were originally used as biological filters. These products are now used in other biological processes such as the transformation of ammoniun ions present in sea water into nitrite and the decomposition of fish feed. The application of zeolitic products has now been extended to the growth of marine microalgae cultures. The present paper describes the results obtained from cultures of the diatom Chaetoceros muelleri which was grown in artificial sea water in the presence of Zecer-56, a natural zeolitic product. Zecer-56 was found to significantly stimulate the growth of C. muelleri cultures.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00310.x
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    Delayed ovarian development and reduced serum steroid levels in female largemouth bass, Micropterus salmoides Lacépède, raised on pelleted feed (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Female largemouth bass, Micropterus salmoides Lacépède, were raised on pelleted feed or a forage diet consisting of goldfish, Carassius auratus (L.). At the start of the present study, forage-fed bass were significantly smaller than pellet-fed bass. Forage-fed bass exhibited a significant increase in body weight, but not length, during the first month of the study; no further increases were seen in subsequent months. Pellet-fed bass did not grow significantly during the course of the study. In forage-fed bass, the gonadosomatic index (GSI) reached maximum levels in March; pellet-fed bass exhibited delayed ovarian recrudescence, reaching peak GSI approximately 4 weeks later than the forage-fed bass. There was no significant difference in the maximum GSI obtained in the two groups of fish. Serum levels of testosterone and oestradiol-17β reflected the pattern of GSI in both groups. Delayed ovarian recrudescence and suppressed serum steroid levels in pellet-fed bass might result from negative feedback effects of elevated levels of steroids found in the pelleted feed. These effects appear to be transient since pellet-fed bass resume ovarian development despite continuing to receive high steroid levels in their feed.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00307.x
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    Culture of the mysid, Mysidopsis almyra (Bowman), (Crustacea: Mysidacea) in a static water system: effects of density and temperature on production, survival and growth (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of animal density and water temperature on the culture of the mysid, Mysidopsis almyra (Bowman), in a static water system were evaluated. An initial set of experiments tested the effects of mysid density on production. Densities of 25, 37.5, 50, 100 and 200 mysids L–1 were placed in trays with 20 L of sea water. Temperatures were maintained at 26 ± 2 °C. A second set of experiments was conducted in the same system at three different temperatures (18 ± 1, 22 ± 1 and 26 ± 2 °C) using a mysid density of 50 mysids L–1 (1000 mysids tray–1). All experiments had a duration of 30 days. The mysids in all trials were cultured at 20 ± 2‰ salinity and fed Artemia nauplii enriched with marine fatty acids. There was a positive correlation between production and mysid densities up to populations of 100 mysids L–1; maximum production was 273 ± 99 hatchlings day–1. At a population density of 200 mysids L–1, high mortality and low production were recorded 4 days after the start of the experiment. The experiments testing different temperatures showed that mysid production was higher at 22 ± 1 °C, although this result was not significant (P 〉 0.05). Growth rates and hatchling survival after 7 days were significantly higher (P 〈 0.05) at 26 ± 2 °C compared to survival and growth at 18 or 22 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00309.x
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    Effect of temperature and relative humidity on the tolerance of the Japanese clam, Ruditapes philippinarum (Adams & Reeve), to air exposure (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Laboratory studies showed that higher relative humidity (RH) and lower air temperature increase the tolerance of the Japanese clam, Ruditapes philippinarum (Adams & Reeve), to exposure. Aerial respiration of the clam was also measured. At high RH, the exposure time which gave 50% survival (LT50) was 1.97 and 1.75 times longer than in low RH at air temperatures of 15 and 25 °C, respectively. At 15 °C, all clams previously acclimatized at 15 °C survived for 58 h at low RH and 102 h at high RH. These differences can potentially be exploited to improve the shipment of clams. The aerial respiration experiment showed that the increase of the oxygen consumption rate at 25 °C was greater than that at 15 °C, following an increase in exposure time. The aerial respiration rates of the clams were ≈ 41.6% and 50.0% of those in water at 25 and 15 °C, respectively. The survival of the clams in air was dependent on aerobic rather than anaerobic respiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00303.x
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    Astaxanthin deposition in fillets of Atlantic salmon Salmo salar L. fed two dietary levels of astaxanthin in combination with three levels of α-tocopheryl acetate (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The influence of α-tocopheryl acetate (α-TOAc) on plasma concentration and fillet deposition ofdietary astaxanthin was investigated in Atlantic salmon Salmo salar L. The diets were added 30 or 50 mg kg–1 astaxanthin, and 200, 400 or 800 mg kg–1α-TOAc at each astaxanthin level. Improved flesh deposition of astaxanthin by 8–14% was achieved for fish fed diets with 30 and 50 mg kg–1 astaxanthin, respectively, by the dietary addition of 800 compared with 200 mg kg–1α-TOAc. These results were supported by CIE[1976]L*a*b* tristimulus redness measurements (a* value). Plasma astaxanthin concentration mirrored the muscle astaxanthin concentration in the groups of fish fed a diet containing 30 mg kg–1 astaxanthin. The salmon fed a high astaxanthin and low α-TOAc diet had the highest plasma concentration of idoxanthin (P 〈 0.05). Astaxanthin retention was significantly higher (P 〈 0.001) in salmon fed 30 mg kg–1 astaxanthin than in those fed 50 mg kg–1 astaxanthin, but was not significantly affected by dietary α-TOAc. Liver weight, body weight, specific growth rate, feed/gain ratio and mortalities were not affected by dietary α-TOAc levels. In conclusion, the dietary addition of α-TOAc appears to increase astaxanthin fillet deposition in salmonids and may reduce the demand for astaxanthin supplementation. The effect was rather small and requires verification.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00355.x
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    Intranuclear inclusion bodies in the hepatopancreas in cultured penaeoid shrimp Litopenaeus vannamei (Boone) in Ecuador (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00379.x
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  • 59
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    Computer-controlled freezing of rainbow trout Oncorhynchus mykiss (Walbaum) spermatozoa for routine programmes (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of extender composition and freezing rate on cryopreservation efficiency of refrigerated spermatozoa of rainbow trout Oncorhynchus mykiss (Walbaum) were evaluated in order to test the suitability of a computer-controlled ultrafreezer to cryopreserve milt samples obtained in field conditions and stored for several hours. A very highly significant first-order interaction between freezing rate and the type of extender was found. Six of the eight experimental variants did not differ significantly, resulting, after fertilization of eggs with cryopreserved sperm, in a range of 62.3–74.8% of eyed embryos. This procedure was effective for samples stored at 1 °C for 2 days.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00381.x
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    Artificial spawning of carp Cyprinus carpio L.: differences between the effects on reproduction in females of Israeli strain Dor-70 and its cross-breed treated with carp pituitary and Ovopel (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects on carp reproduction were investigated in females of the Dor-70 strain and a cross-breed of this line with a Hungarian one of carp pituitary and Ovopel as ovulation stimulators. It was clear that, in the case of the Ovopel treatment, a higher percentage of females spawned, although the weight of eggs obtained was less than that yielded by hypophysed fish, the differences being highly significant (P ≤ 0.01) with respect to the weight in grams and to percentage of female body weight. No statistically significant differences were determined in the quality of eggs, measured by both the fertilization percentage and the percentage of living embryos, obtained after the two stimulators were used. Neither the provenance of females nor the interaction of female provenance and the stimulator has any effect on the traits investigated. The correlation between the percentage of fertilization and the percentage of live embryos was 0.54 for strain Dor-70 and 0.95 for the cross-breed. The multiple regression equations were calculated for strain Dor-70 and for cross-breed 5 separately, where the percentage of living embryos constituted a dependent variable and the mass of a female, mass of eggs in grams and the percentage of fertilization were independent variables. We appraised the regressions as significant for Dor-70 (P ≤ 0.04) and highly significant for the cross-breed (P ≤ 0.0001).
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00350.x
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    Genetic changes in Oreochromis shiranus (Trewavas) associated with the early stages of national aquaculture development in Malawi (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A study was carried out to investigate the genetic diversity during domestication of Oreochromis shiranus (Trewavas) and to see if it could be associated with events in the known history of aquaculture development in Malawi. Five polymorphic microsatellite loci were scored in 14 populations of O. shiranus and one population of O. mossambicus (Peters). The mean number of alleles per locus ranged from 4.4 ± 1.03 to 13.2 ± 3.31 and was higher in the wild populations than in the domesticated populations. Other measures of genetic diversity were also lower in the domesticated compared with the wild populations, and the decline in diversity was correlated with the time elapsed since the founding of the farm stocks. Ordination analysis grouped domesticated populations into three: (1) those that trace their genealogy from Lakes Chiuta and Chilwa populations and are now spread all over the country; (2) those that come from Lakes Malawi and Malombe; and (3) hybrids between O. shiranus and O. mossambicus. Genetic differentiation among farms was strongly influenced by the pattern of known exchanges among the farmers and introgressive hybridization that had occurred between O. shiranus and O. mossambicus in the farmers’ ponds. Thus, the process of genetic changes in the species subsequent to domestication are best explained and predicted by socio-economic factors that influence the behaviour of farmers, rather than by the time-and-distance models of standard population genetics.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00364.x
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    Environmental and product quality in finfish aquaculture development: an example from inland Western Australia (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Aquaculture in Western Australian began with the cultivation of trout in the 1930s, although commercial status was not achieved until the cultured pearl industry was established in Broome in the 1950s. Aquaculture, especially in rural Western Australia, remains a relatively new but expanding industry. Aquaculture development in the agricultural areas of Western Australia represents a potential diversification in large tracts of land where salinization has reduced the economic and ecological sustainability of rural industries. The utilization of saline groundwaters for aquaculture presents a major opportunity for economic expansion. The industry is very small and based around finfish species with wide salinity tolerances. The development of an economically and ecologically sustainable industry requires the application of appropriate environmental management procedures, which provide a high-quality product, minimize the impact of the industry on the surrounding environment and provide a long-term competitive advantage.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00371.x
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    Editorial (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00357.x
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    Modelling fish food consumption with artificial neural networks (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00361.x
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    Galanin and β-endorphin as feeding regulators in cyprinids: effect of temperature (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of intracerebroventricular (ICV) and intraperitoneal (IP) administration of galanin and β-endorphin on food intake have been studied in satiated tench held at 21 ± 2 °C. Food intake was evaluated at 0–2 h and 2–8 h after injection. The same treatments were carried out in tench and goldfish acclimated to 10 ± 1 °C. Central administration of either galanin or β-endorphin significantly increased food intake at 2 h and 8 h after injection in tench acclimated to 21 ± 2 °C, but no change in feeding was observed after IP treatments. Low temperature (10 °C) significantly reduced food intake in both tench and goldfish, and neither central nor peripheral administration of galanin or β-endorphin was found to modify feeding. The results indicate that galanin and opioids play a role in the central regulation of feeding in tench, but the stimulatory effect of these neuropeptides did not reverse the feeding inhibition produced by exposure to low temperature.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00360.x
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    Influence of stocking density on growth of juvenile red porgy Pagrus pagrus L. under different feeding conditions (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The influence of stocking density and feeding regime on the growth of red porgy was studied during winter and spring 1997. Fish were held in 500-L tanks at densities of either 50 or 100 fish per tank, and were fed by means of self-feeders under 6 h restricted (day or night) or free-access feeding regimes. Fish were tagged individually, and weight gain was recorded by individual weighing every second week over an 8-week period during each season. In winter, growth was influenced by feeding time. Fish tended to grow best when fed without restriction and worst when fed at night, although differences were not significant when tank means were compared. Stocking density was influential in the spring trial. Fish stocked at low density and feeding freely grew better than high-density fish that fed either freely or at night. The division of fish into three size classes revealed that, within each treatment, no differences occurred among classes, but growth of fish belonging to the same class was influenced by rearing conditions. No significant differences were found among feeding regimes in terms of the coefficients of weight variation ratio (CVf:CVi) and feed efficiency.
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    Pattern of feed intake in four species of fish under commercial farming conditions: implications for feeding management (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Meal duration and feed ingestion rate were measured in sea cage-reared Atlantic salmon Salmo salar, rainbow trout Oncorhynchus mykiss, yellowtail Seriola quinqueradiata and red sea bream Pagrus major fed dry extruded feed in discrete meals. At the population level, satiation times in yellowtail, salmon and trout were typically about 15–25 min, but time to satiation was longer (60–90 min) in red sea bream. In all species, feed ingestion rate declined progressively during the course of the meal as the fish became satiated. Initial feed ingestion rates in salmon were ≈ 0.3–0.5 kg feed tonne fish–1 min–1 and in trout 0.5–0.9 kg feed tonne fish–1 min–1, although the capacity to deliver feed may have restricted ingestion. Water temperature had little effect on ingestion rates, possibly because the number of meals per day (1–3) was varied with water temperature, and this may have standardized hunger level at the start of meals. Yellowtail ingested feed at ≈ 3.5 kg feed tonne fish–1 min–1 at water temperatures of 18 °C and 28 °C, whereas red sea bream ingested feed at initial rates of 0.6 and 1.4 kg feed tonne fish–1 min–1at 26.5 °C and 18 °C respectively. The findings are discussed in relation to feeding strategies to minimize interfish competition for feed and to improve the ability of fish farmers to detect the point at which fish are satiated.
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    Diurnal and seasonal variation in feeding patterns of Atlantic salmon, Salmo salar L., in sea cages (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Atlantic salmon, Salmo salar L., in sea cages exhibit feeding patterns that vary both diurnally and seasonally. Hitherto, there are no data reporting feed rate and its variation through a complete annual cycle. Here we present data from Scotland showing diurnal and interseasonal variation in feeding patterns and feeding rates of Atlantic salmon fed daily to satiation from shortly after transfer to seawater until harvest about 11 months later. A major feeding peak regularly occurred soon after dawn, and feeding rates remained high for approximately one hour. Over the remainder of the day, the fish fed at a lower but steady rate. Relative feed intake varied over the trial, being initially high in summer followed by a sharp decline in autumn, and then further declining until fish reached harvest size at the beginning of the following summer. Further investigations of the relationship between variation in circannual feeding patterns and environmental parameters should now be carried out to improve the understanding of the mechanism behind these patterns.
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    Periphyton fouling as a marginal energy source in tropical tilapia cage farming (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: In aquaculture, the benefit of autotrophic production within land-based ponds for fish production has long been recognized. In cage culture, organisms growing on the cage net have so far only been considered as a problem. This study investigated the potential production of periphyton on cage nets used in a tropical mixed tilapia culture of Oreochromis mortimeri (Trewavas), Tilapia rendalli (Boulenger) and Oreochromis niloticus (Linnaeus) in Lake Kariba, Zimbabwe. The production of periphyton was assessed experimentally and compared with the energy demand of the caged fish. The tilapias were found to graze intensively on the net, and the primary production of periphyton on the cage net was ≈ 1% relative to the energy demands of the fish.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00344.x
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    Plasmatic levels of cortisol in the response to acute stress in Nile tilapia, Oreochromis niloticus (L.), previously exposed to chronic stress (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Many studies have been made about the physio-logical effects of isolated chronic or acute stress. However, few studies have been made to assess the combination of both responses. The fish submitted to chronic stress may be subjected to an additional acute stressor. The aim of the present work was to evaluate the acute stress response in Nile tilapia Oreochromis niloticus (L.) previously subjected to chronic stress. For this, two experiments were performed. In the first experiment, the fish were subjected to chronic stress followed by an additional acute stress. In the second experiment, the fish were submitted only to an acute stress. The data showed that Nile tilapia fingerlings can adapt to chronic stress situations, and this decreases, but does not eliminate, their capacity to respond to an additional acute stressor. In both experiments, plasma cortisol levels reached a peak 1 h after administration of the acute stressor. In fish previously submitted to chronic stress, the highest concentration of plasma cortisol measured was 196 ng mL–1. This value was significantly different from the cortisol concentration obtained in the second experiment (267 ng mL–1) with non-chronically stressed fish. The data also suggest that the chronic stress response can provoke a reduction in performance and growth rates compared with non-stressed fish.
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    Artificial fertilization in turbot, Scophthalmus maximus (L.): different methods and determination of the optimal sperm–egg ratio (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: With the aim of improving artificial fertilization (AF) in turbot, Scophthalmus maximus (L.), a series of fertilization experiments was carried out under dry conditions and different wet conditions (eggs/sea water: 2V/V and V/V). Another series of fertilization experiments was carried out with different quantities of sperm pool to determine the optimal ratio of spermatozoa to eggs for each AF method. Sperm pool from two males and eggs from spawns with a viability rate of 〉 70% were used. The sperm pool’s density (0.4–5.18 × 109 sperm mL–1) and motility (1–5) had been assessed previously. Significantly different fertilization rates were found when comparing 2V/V and V/V wet conditions. Significantly higher fertilization rates were found in dry fertilization when the sperm–egg ratio was 〉 9000 spermatozoa per egg and, under wet condition V/V, at 3000–4000 spermatozoa per egg.
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    Settling rate characteristics and nutrient content of the faeces of Atlantic salmon, Salmo salar L., and the implications for modelling of solid waste dispersion (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00334.x
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    The reproductive biology of the amberjack, Seriola dumerilii (Risso 1810). I. Oocyte development in captivity (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A study of the reproductive biology of the amberjack, Seriola dumerilii, held in captivity was carried out, describing oogenesis as well as the different stages of the ovarian cycle. Seven stages of oocyte development, as well as oogonia, were distinguished. Cortical alveoli were hardly detectable within the oocyte, as they were small, sparse and contained few mucopolysaccharides. It is suggested that their role in the fertilization process might be less important than in other teleost species. Fish aged 3 and 4 years were found to be sexually immature, with ovaries containing only previtellogenic oocytes. Vitellogenesis started in December in fish aged 4 + years. Late-developing ovaries showing deposition of yolk protein granules were found at the end of the 5th year of life (May) in specimens measuring 80.0 ± 3.5 cm standard length. This should be regarded as the minimum size at which sexual maturity is reached in S. dumerilii. Final vitellogenesis and oocyte maturation were, however, inhibited in captivity, and extensive follicular atresia took place as the natural spawning season approached. It is suggested that insufficient gonadotrophic stimulation because of confinement stress may be the cause of failed maturation and spawning in this species under culture conditions.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00336.x
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    Test of size-specific mass selection for Nile tilapia, Oreochromis niloticus L., cage farming in the Philippines (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: One generation of mass selection based on the collimation procedure (early culling of large fry) was applied on Nile tilapia, Oreochromis niloticus L., in net cages set in Laguna de Bay, Philippines. The objective was to test the effectiveness of a low-cost, small-scale broodstock improvement procedure in this culture environment. Directional selection was performed in two steps after initial removal of large fry at 21 days. Selection of parents and testing of the offspring were also conducted in hapa net cages set up in Laguna de Bay. The selection resulted in a significant positive response of 3% relative to the control, which represents a projected 34% gain over 5 years in Laguna cage culture. The realized heritability is ≈16%.
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    Changes in rainbow trout, Oncorhynchus mykiss (Walbaum), body composition with weight (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
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    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00320.x
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    Effects of dietary protein on growth and body composition of Nile tilapia, Oreochromis niloticus L. (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of dietary protein (25%, 30%, 35%, 40% and 45%) on growth, survival, feed conversion ratio (FCR), protein efficiency ratio (PER) and body composition were investigated for four sizes (0.51, 45, 96 and 264 g) of Nile tilapia, Oreochromis niloticus L. In all four experiments, there was a progressive increase in growth with increasing dietary protein. In fry (0.51 g), significantly higher growth, survival and feed conversion were recorded for fish fed 40–45% rather than 25–35% protein diets. Similar trends for growth and FCR were also noted in 45 g fish. For larger (96 and 264 g) tilapia, significant differences in growth and FCR were found only between fish fed 25% and 30–45% protein diets. FCR and PER decreased with increasing weight of fish, and both were found to be negatively correlated with dietary protein level. Whole-body composition of the smallest fish was significantly influenced by dietary protein content. Percentage body protein of the fish fed 40–45% protein was higher than that of fish fed 25–35% protein diets, whereas lipid content decreased with increasing dietary protein level. In 45 g fish, both protein and lipid contents were higher in fish fed 25% and 30% protein diets than in those fed 35–45% protein diets. In larger tilapia, no significant influence of dietary protein level on body protein content was found. Percentage lipid decreased with increasing dietary protein level, and no definite trends in ash content were found. The results of these studies indicate that O. niloticus fry (0.51 g) should be reared on a practical diet containing 40% protein, and larger tilapia (96–264 g) on a diet containing 30% protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00343.x
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  • 77
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    Does Carnobacterium divergens isolated from Atlantic salmon, Salmo salar L., colonize the gut of early developing turbot, Scophthalmus maximus L., larvae? (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00269.x
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  • 78
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    Effect of heat-treated feed and exogenous zymogen on survival and growth of grey mullet, Liza ramada (Risso), larvae in Egypt (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A preliminary trial and two experiments were carried out to study the effect of heat-treated feed and exogenous zymogen on the survival and growth of grey mullet, Liza ramada (Risso), larvae. The fish were held in glass aquaria supplied with continuous aeration and salt water, which was changed daily. Two test diets (40% crude protein) formulated from commercial ingredients were used. In the preliminary trial, diet A was either heat treated in an autoclave using a maximum pressure of 1.2 kg cm–2 for 15 min, or supplemented with exogenous zymogen at rates of 0%, 2%, 4%, 6% or 8% of the diet. In experiments 2 and 3, four heat treatment times (0, 10, 20 or 30 min) using the previous pressure and three exogenous zymogen supplementation rates (0%, 2% or 4%) were evaluated in a 4 × 3 factorial arrangement for effects on the survival and growth of grey mullet using diet B. Zymogen and vitamins were added to the diets after heat treatment. In addition to survival and growth, dissolved oxygen, temperature and salinity were measured periodically through the study. The grey mullet larvae were introduced to the treatments 24 h after transportation to the laboratory in experiment 2 and after 3 weeks acclimatization in experiment 3. In the preliminary trial, significant differences in survival rates were observed after 7 days for larvae maintained at heat-treated diet A and diet A supplemented with 4% exogenous zymogen. In experiment 2, significant differences in weight gain corresponded to increasing dietary zymogen in diet B. Likewise, the percentage of survival rate increased significantly starting from week 2 as zymogen increased in diet B. Heat treatments in diet B had no significant effect on weight gain of grey mullet after 2 weeks. However, significant differences in survival rate corresponding to heat treatments were observed for grey mullet larvae after 4 weeks in experiment 2. Diet B heat-treated for 20 min with 4% zymogen gave the best results for larval survival rate and growth. Although the larvae were acclimatized for 3 weeks to salinity using the best diet of the second experiment before starting the third experiment, the same results were observed after 3 weeks. Further experiments must be performed to confirm the best conditions for acclimatization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00297.x
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  • 79
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    Effect of different broodstock densities on the reproductive performance of Nile tilapia, Oreochromis niloticus (L.), in a recycling system (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The present study was conducted to evaluate the effect of different stocking densities on the seed production of Nile tilapia, Oreochromis niloticus (L.), under intensive recycling hatchery system conditions. Males and females with mean body weights of 163.2 and 105.0 g, respectively, were stocked at three broodstock densities (4, 8 and 12 fish m–2) at a male:female ratio of 1:3 in 1 × 1 × 0.43 m (W × L × H) fibreglass tanks. The tanks were illuminated at 2500 lux for 18 h day–1 and the water temperature was maintained at 29 ± 1 °C. Effluent from spawning tanks was recycled through a biological filter with 10–15% replacement of new water per day. The experiment lasted for 126 days. The results showed that breeders stocked at 4 fish m–2 had significantly higher (P 〈 0.05) mean values for total seed production, seed kg–1 female day–1, seed female–1 day–1, seed m–2 day–1 and spawning synchrony than at 8 and 12 fish m–2 broodstock densities. The mean percentage of seeds in the yolk-sac and swim-up fry stages was highest at 4 fish m–2 broodstock density. However, the recovery rate was not affected by broodstock density. It is recommended that further research should be conducted to determine whether weight m–2, number m–2 or age of broodstock should be the basis for stocking broodstock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00311.x
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  • 80
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    Impact of culture intensity and monsoon season on water quality in Thai commercial shrimp ponds (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The present authors investigated the impact of farming intensity and the prevailing season on water quality in intensive tropical shrimp farms. The weekly water quality samples from the inlets and production ponds of two commercial shrimp farms operating partial water exchange schedules and representing low and high farming intensities in Thailand (with Penaeus monodon Fabricius production rates of 4 and 9 t ha–1 cycle–1, respectively) were analysed over two consecutive production cycles, covering the wet (monsoon) and dry seasons. Significant differences in inlet water quality between farms occurred only in salinity, temperature and suspended solids. The present authors assessed impacts of farming intensity and season on production pond water quality parameters using: (1) an analysis of variance ( anova) of measurements in replicate ponds during the final month of the production cycle; and (2) a trend analysis which classified trends in parameters over the cycle as externally or internally determined. The prevailing season was found to have a strong impact on salinity, temperature, pH, nitrate, dissolved reactive phosphorus, total phosphorus and dissolved oxygen in the final month of the cycle. The trends in these parameters were largely externally determined or absent. Nitrite and chlorophyll a were affected by production intensity in interaction with season and showed mainly internally determined trends. This indicates that nitrogen transformation processes responded to input levels as well as seasonal influences. Ammonia was highly variable and no significant intensity or season effects were detected, but trends were internally determined only at high intensity and more pronounced in the dry rather than the wet season. The results indicate strong seasonal effects on water quality in tropical shrimp ponds, direct in some parameters and indirect in others, including those linked to nitrogen transformations. The mechanisms of seasonal variation and the implications of these changes for water quality management call for further investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00308.x
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  • 81
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    The effects of ration level on feed intake and growth, and compensatory growth after restricted feeding, in turbot Scophthalmus maximus L. (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Feed intake and growth were studied in groups of turbot fed daily rations of 0.25%, 0.38% and 1% of body weight day–1 for 41 days. Then, all groups were fed 1% of body weight day–1 for the next 34 days. The two restricted rations resulted in reduced growth rates (30% and 60% of fully fed controls), and there was a tendency for increased growth heterogeneity (coefficient of variation increased from about 100% to about 150%) compared with controls on full rations. Nevertheless, restricted rations did not result in any increase in size heterogeneity with the passage of time: the coefficient of variation for weight changed little irrespective of feeding treatment. The turbot became hyperphagic and displayed compensatory growth after the change from restricted to excess feeding, with compensatory growth being most marked among the fish that had been subject to the most severe feed restriction. The results provided some evidence of increased variability in feeding and growth within groups of turbot fed restricted rations, possibly as a result of the establishment of weak feeding hierarchies. When feeding restrictions were lifted, the turbot that had reduced growth under feed restriction were able to completely compensate for lost growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00368.x
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  • 82
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    A pump-pot nursery system for rearing juvenile New Zealand dredge oysters Tiostrea lutaria (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A wave-operated nursery system was developed for growing hatchery-produced spat of the New Zealand dredge oyster Tiostrea lutaria (Hutton) through to a size (≈ 20 mm) suitable for on-growing in conventional oyster farming equipment. The pump-pot enabled cultch-free dredge oyster spat to be transferred from hatchery upwellers at a small size (〉 2 mm), thus avoiding the need to supply them with cultured algae to maintain a high growth rate. The wave-activated pumping action of the pot maintained a sufficient flow of water through the pot to achieve rapid growth of small spat held at high densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00375.x
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  • 83
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    Infection of IHHN virus in two species of cultured penaeoid shrimp Litopenaeus vannamei (Boone) and Litopenaeus stylirostris (Stimpson) in Ecuador during El Niño 1997–98 (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Infectious hypodermal and haematopoietic necrosis virus (IHHNV) was first noted in blue shrimp Litopenaeus stylirostris (Stimpson) in mid-1981. Since that time, at least 12 species of penaeoid shrimp have been reported to be infected with IHHNV. Pacific white shrimp Litopenaeus vannamei (Boone) represents a shrimp species highly refractory to the disease, whereas L. stylirostris was highly susceptible to the disease. Since the beginning of the shrimp farming industry in Ecuador, viral diseases have been observed in L. vannamei and L. stylirostris. Of these, L. vannamei represents ≈ 80% of cultured shrimp. Histopathology, ultrastructure and in situ DNA hybridization confirm the presence and assess the prevalence of IHHNV in pond-reared shrimp, and especially in abnormally small animals of both species. Although IHHNV may be considered enzootic in cultured L. vannamei in Ecuador, we did not find high prevalence (Cowdry A bodies) in specimens of diseased pond shrimp before 1996. From that time to 1998, a higher prevalence of IHHNV has been observed in both species. The epizootic of the IHHNV disease has been related to the oceanographic and climatological conditions caused by El Niño. In addition, it has been suggested that large quantities of wild shrimp post-larvae of both species that were stocked in shrimp farms, infected as latent carriers in 1997, from which the virus could spread to a larger population of these shrimp in 1998.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00378.x
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  • 84
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    Removal of particle-associated bacteria by prefiltration and ultraviolet irradiation (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The combined effect of prefiltration and ultraviolet (UV) irradiation on the removal of bacteria associated with plankton fragments was investigated in an experimental flowthrough system. The system was supplied by sea water containing fragments of Artemia nauplii in the size range 10–240 μm diameter (mean = 66 μm), as determined by particle size analysis. By applying an UV dose of 10 mJ cm–2, the number of colony-forming units (CFU) was reduced from 7.4 × 105 per 100 mL to 2.0 × 103 per 100 mL. Increasing the dose to 13 or 22 mJ- cm–2 did not result in any further reduction, suggesting that bacteria associated with Artemia fragments were protected. This protection hypothesis was supported by improved overall bacterial removal efficiency by prefiltration. At the highest dose (22 mJ cm–2), more than 5 log10 units total reduction was obtained by prefiltration using 50-μm mesh sizes. The reductions relative to the unfiltered sample were 1.4, 2.4 and 3.0 log10 units using mesh sizes of 355, 80 and 50 μm respectively. It is concluded that sea water for aquacultural purposes should be filtered to remove particles before UV disinfection, thereby improving the overall bacterial removal efficiency and reducing the risk of introducing UV-shielded bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00349.x
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  • 85
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    Use of duckweed, Spirodela polyrrhiza L. Schleiden, as a protein feedstuff in practical diets for tilapia, Oreochromis niloticus L. (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The use of solar-dried duckweed, Spirodela polyrrhiza L. Schleiden, as a dietary protein component for tilapia, Oreochromis niloticus L., reared in glass tanks was evaluated. Six isonitrogenous diets (30% crude protein) were fed to all-male tilapia fingerlings for 56 days. The fish meal protein in the diets was substituted at a rate of 5%, 10%, 20%, 30% and 100% with duckweed. A diet without the duckweed served as a control. Growth performance and nutrient utilization of fish were based on daily weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio and protein productive value. There were no significant differences (P 〉 0.05) in growth performance and nutrient utilization of fish fed on diets containing up to 20% duckweed inclusion and the control. However, increases in dietary duckweed inclusion resulted in progressively reduced growth performance and nutrient utilization of fish. Diet without fish meal (100% duckweed) gave the poorest result. The most cost-effective diet in terms of cost per unit gain in weight of fish was obtained with 30% duckweed dietary inclusion. The result showed that solar-dried up to 30% duckweed dietary inclusion as a replacement for fishmeal in practical diets supported fish growth and was cost-effective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00318.x
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  • 86
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    Effect of proteolytic enzyme addition to a practical feed on growth of the Pacific white shrimp, Litopenaeus vannamei (Boone) (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Four commercially available proteolytic enzymes active over a wide pH range were assessed as shrimp feed additives. Feeds were formulated to contain 1% of the test enzymes by weight. A feed of the same composition with no enzyme addition served as a control. In vitro feed protein digestibility of the feeds was determined using a modified pepsin digestibility method. In vitro protein digestibility results indicated that commercially available proteases added to a shrimp feed formulation and then hot pelleted/dried did retain enzyme activity. Feeds exhibited low weight losses through leaching (≤ 10.9%) and low or no losses of protein content (≤ 2.7%), indicating that the test feeds were available in their entirety to the shrimp. An 8-week feeding trial using the enzyme-supplemented feeds was conducted to evaluate shrimp growth. Mean shrimp survival was high for all treatments (〉 90%). One-way analysis of variance did not detect significant differences (P 〉 0.05) among feeds in terms of survival, weight gain, specific growth rates and feed–weight gain ratios. Although in vitro digestibility indicated the presence of active enzymes in the feed, the feeding trial revealed that shrimp growth was not enhanced by the inclusion of proteases in these feeds. This study provides sufficient proof to emphasize the importance of in vivo investigations before enzyme-supplemented feeds are used with shrimp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00333.x
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  • 87
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    Environmental determination of dragonfly assemblage in aquaculture ponds (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Odonate larvae are important components of aquatic environments in tropical areas. They also develop in aquaculture ponds, where they can cause economic losses. In this study, we have tried to describe the general community patterns in aquaculture ponds in Viçosa, south-eastern Brazil. Our aim is to evaluate how environmental and bionomic factors can determine their composition and species richness. We identified two groups of species (plants and bottom-dwellers) based on larval microhabitat preferences. Vegetation determines the occurrence of some species whose adults select certain plants for oviposition. The ponds with more extreme conditions (extensive cover of plants or vegetation absent) showed lower species richness than those with intermediate conditions. Coryphaeshna adnexa and Brachmesia furcata were of larger size but had low abundance or were only collected accidentally. Species of intermediate size (Tramea cophysa, Micrathyria spp., Orthemis discolor and Erytrodiplax fusca) were more abundant and are considered as potential predators of fish fry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00338.x
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  • 88
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    Evaluation of the secondary stress response in healthy Nile tilapia (Oreochromis niloticus L.) after treatment with a mixture of formalin, malachite green and methylene blue (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: To determine the effects of exposure to a mixture of formalin, malachite green and methylene blue (FMC) on the secondary stress indices, changes in glucose, phosphorus, calcium, magnesium, sodium, potassium and haematocrit were monitored in healthy Nile tilapia, Oreochromis niloticus L. Fish were exposed separately to varying concentrations of a mixture of formalin, malachite green and methylene blue (0.1, 0.5 and 1 p.p.m.) for 1, 10 and 60 min. In general, treatment of fish with FMC elicited marked elevations of plasma glucose. Plasma phosphorus levels dropped after FMC treatment. In fish exposed to FMC, calcium levels in general were lower than those of the controls. Magnesium levels were not influenced by FMC treatment. Plasma sodium and potassium levels showed an unclear pattern for differing FMC concentrations and exposure times. Haematocrit values were affected by FMC treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00341.x
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  • 89
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    Controlled anaesthesia of Rana catesbeiana (Shaw) and Rana pipiens (Schreber 1792) using xylocaine delivered by spray (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00328.x
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  • 90
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    Replacing dietary corn with barley seeds in Nile tilapia, Oreochromis niloticus (L.), feed (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Four isocaloric–isonitrogenous rations containing 0%, 15%, 30% and 51% of ground barley seeds as a replacement for dietary corn were fed to three replicate groups of Oreochromis niloticus (Linnaeus) fingerlings with a mean initial weight of 3.5 g. The randomly selected fish were tested for 9 weeks in 60 L circular tanks. Each tank was considered as an experimental unit. The tanks were put together in a water recirculating system using filtered and aerated ground well water (24 ± 3 °C). Tilapia weight gain, feed conversion, specific growth rate and protein efficiency ratio were similar in fish fed diets containing 15% and 30% barley and were superior to those fed diets containing 0% control and 51% barley. There were no differences between tilapia fed diets containing 0% and 51% barley. Body moisture, crude fat, crude protein and total ash did not change as the level of barley in the feeds was increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00323.x
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  • 91
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    A comparative tissue distribution study of oxytetracycline in rainbow trout, Oncorhynchus mykiss (Walbaum), and chinook salmon, Oncorhynchus tshawytscha (Walbaum) (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Oxytetracycline (OTC), a broad-spectrum antibiotic, is used widely to treat bacterial diseases in farmed fish. In the present study, the time course of OTC concentrations in freshwater rainbow trout, Oncorhynchus mykiss (Walbaum), and seawater chinook salmon, Oncorhynchus tshawytscha (Walbaum), were compared, tissue by tissue, after receiving a bolus dose of the antibiotic (5 mg kg–1 or 50 mg kg–1) intra-arterially (i.a.). The OTC concentration–time profiles of rainbow trout tissues were found to be very similar to those of the corresponding tissues in chinook salmon. Therefore, neither water salinity nor fish species seemed to play an important role in the disposition and elimination of OTC in these salmonids. In a separate experiment, rainbow trout were implanted surgically with a urinary cannula and received a single dose of OTC (50 mg kg–1) i.a. Urine was collected from the cannula daily for 13 days. The amount of OTC excreted into the bile was found to be larger than that eliminated by the urine. These results show the similarity of OTC pharmacokinetics in freshwater rainbow trout and seawater chinook salmon and render support in using a single fish species to study the pharmacokinetics of a drug for other species in the same taxon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00329.x
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  • 92
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    Comparative costs of postlarval production from wild or domesticated Kuruma shrimp, Penaeus japonicus (Bate), broodstock (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The present study compares the relative costs of stocking ponds with postlarvae from wild or domesticated Kuruma shrimp, Penaeus japonicus (Bate), broodstock. Wild broodstock were obtained from a commercial trawler. Domesticated broodstock were reared to harvest size (wet weight = 25 g) on a commercial farm and then transferred to controlled environment tanks where they were grown to a final wet weight of 50 g. The costs of stocking ponds with postlarvae were calculated from the observed reproductive output, the costs of purchasing wild broodstock and the costs of domesticated broodstock production in the controlled environment facility. Domesticated P. japonicus spawned comparable numbers of eggs to wild broodstock of similar size, but hatching success was significantly lower. A total of 12 domesticated P. japonicus broodstock would be needed to produce the postlarvae to stock a 1-ha pond, compared to only six wild broodstock. However, the much higher relative costs of wild broodstock means that the cost of using their postlarvae would be Aus$851 per pond compared to Aus$390 for domesticated broodstock. The present authors conclude that the use of domesticated P. japonicus broodstock could be a cost-effective alternative to wild broodstock in Australia and in other countries where P. japonicus is farmed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00306.x
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  • 93
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    Leaching, palatability and digestibility of oxytetracycline and oxolinic acid included in diets fed to seabass Dicentrarchus labrax L. (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The leaching of oxolinic acid (OA) and oxytetracycline (OTC) from medicated feeds, as well as the palatability and digestibility of these drugs were investigated in seabass Dicentrarchus labrax L. (350 g) at 16 °C and 24 °C water temperature. Oil-coated OA and OTC on feeds were greatly affected by leaching at 16 °C (losses of 55.5% and 42.5% for OA and OTC respectively) and 24 °C (32% for OA and 47% for OTC). However, a significant reduction in drug loss resulting from leaching was evident when the antibiotics were mixed with the diet at 16 °C (5% for OA and 6.5% for OTC) and 24 °C (10% and 20% for OA and OTC respectively). Increased water temperature induced a significant effect on the leaching of both drugs when mixed with the feed, but did not affect the loss of oil-coated drugs. There was a significant reduction in feed consumption of fish fed a diet with oil-coated OTC (90% and 92% at 16 °C and 24 °C respectively), whereas intake of feed containing oil-coated OA was only slightly affected (10% at 16 °C, 12% at 24 °C). The depressed palatability of feeds containing oil-coated OTC was overcome by mixing the drug with the diet. Both antibiotics were well digested by seabass (94% and 85% for OA and OTC respectively) at 24 °C; however, more than one-third of each drug was recovered in the faeces at 16 °C (64% and 59% for OA and OTC respectively). The significance of these findings for the interaction between fish therapy and marine environment is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00410.x
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  • 94
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    The effects of stocking density and social interaction on acute stress response in Nile tilapia Oreochromis niloticus (L.) fingerlings (1999)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 30 (1999), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Several researchers have demonstrated that the stocking density and social interactions between conspecific fish have significant influence on stress response. Nile tilapia Oreochromis niloticus (L.) is a teleost fish with hierarchical organization. Nile tilapia fingerlings (20 ± 5 g) were distributed in 30 tanks, 12 tanks with single fish and six with paired, groups of five and 10 fish, respectively, and held in these 100-L plastic tanks for 60 days. Six tanks of single fish and three of other groups received an acute stressor on the 61st day. The control fish reared singly and in pairs showed a plasma cortisol concentration similar to that normally found as a resting cortisol concentration in other fish. One surprising result was the absence of the formation of a hierarchical dominant/submissive relation between the fish held in pairs. One possible explanation for this result is the volume of the tank, so that each fish exerted a territorial position in a corner of the tank, and the fighting and antagonistic encounters did not occur. In the five- and 10-fish groups, the resting plasma cortisol concentrations were higher, which may indicate a chronic stress response during the 60 days of the experiment, attributable to social stress. The application of an acute stressor significantly increased the plasma cortisol levels in all stocking densities, with values reaching 135–298 ng mL− 1. When comparing the stressed fish, the 10-fish groups showed a more intense stress response in relation to the other groups.
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    URL: http://dx.doi.org/10.1046/j.1365-2109.1999.00419.x
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  • 95
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    The pathway to noxious cyanobacteria blooms in lakes: the food web as the final turn (1999)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 42 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Cyanobacteria blooms have long been the focus of limnological research as they often represent the ‘end member’ of limnological deterioration under various human impacts. Research over the past several decades has greatly illuminated the ecological factors promoting cyanobacteria blooms but controversy and confusion surround the successful integration of this diverse body of work.2. In this opinion article I attempt to integrate well-known aspects of cyanobacteria bloom ecology (such as the roles of nutrient loading, N:P ratio, and mixing conditions) with more recent developments that highlight the importance of feedbacks within the food web in regulating cyanobacteria blooms. Food-web feedbacks involving stoichiometric mechanisms appear to be particularly important, as accumulating data indicate that the food web influences cyanobacteria not just by regulating the rate of grazing mortality. Rather, trophic interactions may also regulate cyanobacteria dynamics by altering the consumer-driven nutrient recycling regime in a way that shifts the competitive advantage away from cyanobacteria.3. Viewed in this way, cyanobacteria blooms can be seen as probabilistic events that are the end result of a series of key mechanisms involving nutrient loading, physical mixing conditions, and trophic interactions. To successfully manage lake water quality we should take advantage of each node of contingency leading to undesirable blooms. In doing so we will also have a more coherent scientific message to communicate with those directly involved with the socioeconomic politics of water quality decision making.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00471.x
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  • 96
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    Effects of hydrological variation and planktivorous competition on macroinvertebrate community structure in experimental billabongs (1999)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 42 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. To study two factors which are predicted as causing changes to community structure in cut-off meanders (colloquially known in Australia as billabongs, a term of aboriginal origin), 16 experimental billabongs were constructed. These were designed to test two hypotheses: (a) that the structure of macrophyte and invertebrate communities within billabongs is altered by changing the pattern of flooding; and (b) that the presence of small planktivorous fish alters invertebrate community structure and diversity within billabongs.2. An increase in the duration of flooding seems to favour animals better adapted to a greater availability of macrophyte habitat. Changing the seasonality of flooding resulted in prolonging of the time water was available over the summer months.3. The presence of a planktivorous fish appears to affect macroinvertebrate communities through competition with other planktivores. Variable top-down pressure may create differing successional patterns and ultimately different communities at lower trophic levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00473.x
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  • 97
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    Seasonal and interannual variability of plankton carbon isotope ratios in a subarctic lake (1999)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 42 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Carbon isotope ratios (δ13CD) of a herbivorous zooplankter, Daphnia middendorfiana and several environmental variables were investigated during four annual production cycles (1988–92) in Smith Lake, Alaska to determine factors that affect the seasonal and interannual variability of δ13CD.2. δ13CD varied from −44.7 to −31.5 ppt and was significantly correlated with Chl a (r = 0.66, P = 0.0001), weakly correlated with CO2(aq) (r = 0.31, P = 0.07) and uncorrelated with δ13CDIC (r = 0.10, P = 0.70). Carbon isotope fractionation was minimal when Chl a appeared to be optimal. The largest 13C fractionation was associated with the lowest Chl a during early and mid winter periods.3. δ13CD was also significantly correlated with water temperature (r = 0.480, P = 0.0001) and photoperiod (r = 0.62, P = 0.0001), probably suggesting a critical role of physical forcing, particularly solar energy input, in affecting algal photosynthesis and δ13CD in this subarctic lake.4. There was a large interannual variability of δ13CD among ice-cover periods which was partly explained by interwinter differences in the amount of snowfall that affected the flux of solar irradiance to the ice-covered lake.5. Other explanations for δ13CD variability such as species succession, changes in algal cell size and differential use of CO2(aq) and HCO3– were also considered, but cannot account for the observations reported here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00472.x
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  • 98
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    Emergence and lateral dispersal of adult Plecoptera and Trichoptera from Broadstone Stream, U.K. (1999)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 42 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Emergence and inland dispersal of adult stoneflies (Plecoptera) and caddisflies (Trichoptera) from Broadstone Stream, an acidic and iron-rich stream in southern England, were studied over 10 months in 1996–1997. Fifteen pyramidal emergence traps were placed randomly in a 200-m stretch. Three Malaise traps were placed above the stream and six more on each side (one wooded, one open) along a transect at distances of 1, 15, 30, 45, 60 and 75 m from the channel.2. More than 16 000 stoneflies, belonging to 11 species, and just under 400 caddisflies (22 species) were caught. Four dominant stoneflies (Leuctra fusca, Leuctra nigra, Leuctra hippopus and Nemurella pictetii) accounted for 96% and 95% of the catches in the emergence and Malaise traps, respectively. Two caddisflies (Plectrocnemia conspersa and Potamophylax cingulatus) accounted for 63% of the catch in the Malaise traps. Few caddisflies were taken in emergence traps.3. The emergence periods of L. fusca, L. nigra and L. hippopus were well-defined and unimodal, whereas that of N. pictetii was prolonged and erratic. Overall, more females (1285) emerged than males (740).4. Female stoneflies and caddisflies were in the majority in the Malaise traps above the stream. On land, significantly more females than males of L. fusca, L. nigra and P. cingulatus were caught. The sex ratio of the remaining species did not deviate significantly from 1:1.5. The three Malaise traps placed above the stream caught most of the stoneflies though there was also dispersal away from the channel, the numbers caught declining with distance. Exponential models explained between 67% and 99% of the variation in numbers of individuals with distance from the channel in the four common stoneflies. Half the individuals went less than 11–16 m from the stream, while 90% travelled less than 51 m. Significantly more L. nigra and N. pictetii were caught in the woodland than on the open side, whereas L. hippopus showed no overall preference for either side.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00466.x
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  • 99
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    Potential nitrification and cation exchange on litter of emergent, freshwater macrophytes (1999)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 42 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00480.x
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  • 100
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    Effects of prey abundance and light intensity on the mixotrophic chrysophyte Poterioochromonas malhamensis from a mesotrophic lake (1999)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 42 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Previous studies of mixotrophy in the flagellate Poterioochromonas malhamensis (Chrysophyceae) were performed on strains that had been in culture for 〉 30 years. This study aims to compare mixotrophy in a cultured strain with one recently isolated from a mesotrophic lake (Lacawac) in Pennsylvania, U.S.A.2. P. malhamensis from the lake exhibited a nutritional flexibility similar to that of the culture strain, growing phototrophically but inefficiently in comparison to other nutritional modes (growth rate (μ) = 0.015 h−1). Supplementing an inorganic salts medium with 1 mM glucose resulted in a doubling of μ to 0.035 h−1 and 0.033 h−1 in the light and the dark, respectively. Addition of an algal prey, Nannochloris, to the inorganic salts medium increased growth to rates similar to those observed with glucose. Maximum growth of the lake strain, 0.095 h−1, was achieved when bacteria was supplied as food. During growth on bacteria, cellular chlorophyll a (Chl a) decreased from 140 fg cell−1 to 10 fg cell−1 over 22 h when cultured either in the light or dark. In illuminated cultures, cell-specific Chl a concentration recovered to 185 fg cell−1 after bacteria became limiting.3. In contrast to the cultured strain, however, the lake isolate exhibited an inverse relationship between light intensity and ingestion rate. Calculated grazing rates, based upon the ingestion of fluorescently labeled bacteria, were 3.2, 5.2 and 9.4 bacteria flagellate−1 h−1, for P. malhamensis incubated in high light, low light and darkness, respectively. Phagotrophy is thus influenced by a light regime in this predominately heterotrophic mixotroph.
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    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00476.x
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