ALBERT

Notes: Abstract  Trees were regenerated from six white spruce embryogenic clones after cryopreservation for 3 and 4 years, respectively. Genetic stability was evaluated using randomly amplified polymorphic DNA (RAPD) fingerprints. Somaclonal variation was detected in some in vitro embryogenic cultures 2 and 12 months after they were re-established following cryopreservation but not in the corresponding regenerated trees. These results suggest that trees regenerated from cryopreserved cultures in subsequent years are primarily genetically stable in the genomic regions tested and that variation observed due to the in vitro culture process infrequently affects trees regenerated from normally maturing and germinating somatic embryos. However, trees regenerated from somatic embryos that matured or germinated abnormally in in vitro culture exhibited altered RAPD fragment patterns.

Notes: Abstract Plants were regenerated by somatic embryogenesis from long-term callus cultures derived from five garlic (Allium sativum L.) cultivars. Thirty-five of these plants were subjected to RAPD analysis. The frequency of variation was found to be cultivar dependent: approximately 1% in the two clones Solent White and California Late and around 0.35% in another three clones, Chinese, Long Keeper and Madena. Certain band changes were found in regenerants of different cultivars, suggesting the existence of a mutation-sensitive part of the garlic genome. The karyotypes of another 75 regenerants derived from the same callus cultures of three parental garlic clones were examined. Of these plants, 9.3% were found to be tetraploids, 4% aneuploid and 2.6% showed a change in the position of the secondary constriction. No association could be shown between the rate of variation for molecular and cytological characters either by comparing cultivars or examining individual regenerants.

Notes: Abstract   Solanum chacoense Bitter, a wild relative of the cultivated potato, produces several glycoalkaloids, including solanine, chaconine, and the leptines. The foliar-specific leptine glycoalkaloids are believed to confer resistance to the Colorado Potato Beetle (CPB). Using two bulked DNA samples composed of high- and low-percent leptine individuals from a segregating F1 population of S. chacoense, we have identified two molecular markers that are closely linked to high percent solanine+chaconine and, conversely, to nil/low percent leptine. One of these, a 1,500-bp RAPD product (UBC370-1500), had a recombination value of 3% in the F1 progeny, indicating tight linkage. UBC370-1500 mapped to the end of the short arm of potato chromosome 1, in the region of a previously mapped major QTL for solanidine, from a S. tuberosum (solanidine)×S. berthaultii (solasodine) cross. Taken together, these results suggest that either (1) a major locus determining solanidine accumulation in Solanum spp. is on chromosome 1 in the region defined by the RFLP markers TG24, CT197, and CT233, or (2) this region of chromosome 1 may harbor two or more important genes which determine accumulation of steroidal aglycones. These findings are important for the genetics of leptine (as well as other glycoalkaloid) accumulation and for the development of CPB-resistant potato varieties.

Notes: Abstract  A 400-bp RAPD marker generated by a primer of random decamer sequence has been found associated with the male sex phenotype in 14 dioecious cultivars and accessions of hemp (Cannabis sativa L.). The primer OPA8 generates a set of bands, most of which polymorphic among all the individual plants tested, and 1 of which, named OPA8400, present in all male plants and absent in female plants. A screening of 167 plants belonging to different genotypes for the association of the OPA8400 marker with the sex phenotype revealed that only in 3 cases was the 400-bp band was present in plants phenotypically female; on the contrary, in male plants the band was never missing, while in monoecious plants it was never present. Despite this sex-specific association, the sequences corresponding to OPA8400 were present in both staminate and carpellate plants, as revealed by Southern blotting and hybridization with the cloned RAPD band. The RAPD marker was sequenced, and specific primers were constructed. These primers generated, on the same genotypes used for RAPD analysis, a SCAR marker 390 bp in length and male-specific. This SCAR is suitable for a precise, early and rapid identification of male plants during breeding programs of dioecious and monoecious hemp.

Notes: Abstract  Crop germplasm collections contain a considerable percentage of misclassified accessions which may affect the use of germplasm for agricultural crop improvement. The objective of this study was to determine if random amplified polymorphic DNA (RAPD) analysis could be used to reclassify misclassified Triticum accessions. Twelve accessions suspected to be misclassified, based on morphological characters, as either macha or vavilovii wheat were studied using RAPD and cytological analyses. In the RAPD analysis, a dendrogram, based on Jaccard genetic similarity coefficients, grouped 5 dicoccum-like, 1 timopheevii-like, and 6 monococcum-like accessions with Triticum dicoccum, T. timopheevii, and T. monococcum accessions, respectively. These results were confirmed by the cytological analysis. A RAPD marker specific to the D genome was also detected. This study suggests that RAPD analysis can be used to classify germplasm and to distinguish some species in Triticum.

Notes: Abstract  Random amplified polymorphic DNA markers were used to distinguish between nine different Cicer taxa representing the cultivated chickpea and eight other related annual wild species. Of the 75 random10-mer primers tested, only 8 amplified genomic DNA across all the species. A total of 115 reproducibly scorable RAPD markers were generated, all except 1 polymorphic, and these were utilized to deduce genetic relationships among the annual Cicer species. Four distinct clusters were observed and represented C. arietinum, C. reticulatum and C. echinospermum in first cluster followed by C. chorassanicum and C. yamashitae in the second cluster, while C. pinnatifidum, C. judaicum and C. bijugum formed the third cluster. Cicer cuneatum did not cluster with any of the species and was most distantly placed from the cultivated species. Except for the placement of C. chorassanicum and C. yamashitae, deduced species’ relationships agreed with previous studies. In addition, species-diagnostic amplification products specific to all the nine species were identified. The results clearly demonstrate a methodology based on random-primed DNA amplification that can be used for studying Cicer phylogeny and chickpea improvement.

Notes: Abstract  Seven F2 families of faba bean descendent from plants trisomic for chromosomes 3, 4, 5 and 6 were analyzed for isozyme markers and two of these were also studied for morphological and RAPD markers and seed-protein genes. Linkage analysis revealed 14 linkage groups, 8 of which were unambiguously assigned to specific chromosomes. Several QTLs for seed weight were identified, the most important of which, located on chromosome 6, explained approximately 30% of the total phenotypic variation. Comparison of results from Vicia faba with the maps of the related species Pisum sativum L. and Cicer arietinum L. revealed one possible new case of linkage conservation. A composite linkage analysis based on 42 markers analyzed in this and previous studies, where line Vf 6 was also used as the female parental, allowed the new assignment of previously independent linkage groups and/or markers to specific chromosomes. Thus, the number of linkage groups was reduced to 13, each comprising an increased number of markers. No contradictory results were detected, indicating the suitability of the statistical procedure and methodology used so far in the development of the map of this species.

Notes: Abstract  RAPD markers were developed for octoploid×Tritordeum (amphiploid Hordeum chilense×Triticum aestivum) and its parents. Addition lines were used to identify specific RAPD markers for the Hordeum chilense chromosomes detectable in a wheat background. Twelve RAPD fragments have been cloned, sequenced and converted into STS markers. Eleven of these STSs have maintained both the chromosome specificity and the possibility of detection in a wheat background. The use of these markers in multiplexed PCRs facilitates both the efficient and reliable screening of new addition lines as well as the monitoring of introgression of H. chilense in bread and durum wheat.

Notes: Abstract  Fusarium wilt, caused by Fusarium oxysporum Schlecht f. sp. melonis Snyder & Hans, is a worldwide soil-borne disease of melon (Cucumis melo L.). Resistance to races 0 and 1 of Fusarium wilt is conditioned by the dominant gene Fom-2. To facilitate marker-assisted backcrossing with selection for Fusarium wilt resistance, we developed cleaved amplified polymorphic sequences (CAPS) and restriction fragment length polymorphisms (RFLP) markers by converting RAPD markers E07 (a 1.25-kb band) and G17 (a 1.05-kb band), respectively. The RAPD-PCR polymorphic fragments from the susceptible line ’Vedrantais’ were cloned and sequenced in order to construct primers that would amplify only the target fragment. The derived primers, E07SCAR-1/E07SCAR-2 from E07 and G17SCAR-1/G17SCAR-2 from G17, yielded a single 1.25-kb fragment (designated SCE07) and a 1.05-kb fragment (designated SCG17) (the same as RAPD markers E07 and G17), respectively, from both resistant and susceptible melon lines, thus demonstrating locus-specific associated primers. Potential CAPS markers were first revealed by comparing sequence data between fragments amplified from resistant (PI 161375) and susceptible (’Vedrantais’) lines and were then confirmed by electrophoresis of restriction endonuclease digestion products. Twelve restriction endonucleases were evaluated for their potential use as CAPS markers within the SCE07 fragment. Three (BclI, MspI, and BssSI) yielded ideal CAPS markers and were subsequently subjected to extensive testing using an additional 88 diverse melon cultigens, 93 and 119 F2 individuals from crosses of ’Vedrantais’ x PI 161375 and ’Ananas Yokneam’×MR-1 respectively, and 17 families from a backcross BC1S1 population derived from the breeding line ’MD8654’ as a resistance source. BclI- and MspI-CAPS are susceptible-linked markers, whereas the BssSI-CAPS is a resistant-linked marker. The CAPS markers that resulted from double digestion by BclI and BssSI are co-dominant. Results from BclI- and MspI-CAPS showed over 90% accuracy in the melon cultigens, and nearly 100% accuracy in the F2 individuals and BC1S1 families tested. This is the first report of PCR-based CAPS markers linked to resistance/susceptibility for Fusarium wilt in melon. The RFLP markers resulting from probing with a clone-derived 1.05-kb SCG17 PCR fragment showed 85% correct matches to the disease phenotype. Both the CAPS and RFLP markers were co-dominant, easier to score, and more accurate and consistent in predicting the melon phenotype than the RAPD markers from which they were derived.

Notes: Abstract  Genetic variation among 15 accessions of Native American maize from the Great Plains was investigated using random amplified polymorphic DNA (RAPD). RAPDs revealed very high levels of polymorphism among accessions. Banding patterns ranged in percentage polymorphism from 46.7% to 86.2% with an overall mean of 70.7% for the primers analyzed. The construction of genetic relationships using cluster analysis and principal coordinates analysis revealed that RAPDs are successful in confirming hypothesized relationships and in identifying misclassified specimens. Furthermore, the phenogram fails to reveal a strong correspondence between genetic relationships and the geographical position of Native Americans prior to contact. This provides support for the hypothesis that multiple introductions of maize into the Great Plains via trade may have resulted in the great morphological variation found among accessions in the region. Based on these data, it is unlikely that a separate Great Plains race of maize can be distinguished. In general, we conclude that RAPDs are potentially very useful in organizing seed collections and understanding intraspecific genetic differentiation.

Notes: Abstract  The Bs2 resistance gene of pepper confers resistance against the bacterial pathogen Xanthomonas campestris pv. vesicatoria. As a first step toward isolation of the Bs2 gene, molecular markers tightly linked to the gene were identified by randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analysis of near-isogenic lines. Markers flanking the locus were identified and a high-resolution linkage map of the region was developed. One AFLP marker, A2, was found to cosegregate with the locus, while two others, F1 and B3, flank the locus and are within 0.6 cM. Physical mapping of the A2 and F1 markers indicates that these markers may be within 150 kb of each other. Together, these results indicate that the Bs2 region may be cloned either by chromosome walker or landing. The linked markers were also used to characterize gamma-irradiation-induced mutants at the Bs2 locus.

Notes: Abstract  The mitochondrial DNA of various carrot lines was characterized by random amplified polymorphic DNA (RAPD) analysis, and six sequence-tagged sites (STSs) led to identification of the petaloid type of cytoplasmic male sterility (CMS). Using six STS primer combinations, we were able to classify five CMS lines into two groups and eight fertile carrots into six groups. Both the STS1 and the STS4 primer combinations differentiated CMS cytoplasms from the fertile cytoplasms, and the STS2 primer combination revealed two different types of CMS cytoplasms – of Wisconsin Wild and Cornell origins. Cybrid carrot lines with petaloid flowers which had been obtained by asymmetric cell fusion could also be separated from fertile cybrids by the STS1 primer combination. The STS1 fragment contained a homologous sequence with the orfB gene. DNA gel blot analysis indicated that homologous regions to the STS1 fragment existed in fertile types as well as the CMS types, although the restriction fragment size patterns differed. These observations demonstrate that rearrangements involving this region occurred in the mitochondrial genome. The STS4 fragment had a more complicated gene structure, including retrotransposon-like sequences and small segments of chloroplast genome.

Notes: Abstract  The aim of this study was to develop a cultivar identification tool based on molecular analysis and a statistical approach. From the PIC parameter we defined the D parameter, which evaluates the efficiency of a primer for the purpose of identification of varieties; i.e. the probability that two randomly chosen individuals have different patterns. D can be used to compare different types of markers even if only the allelic frequencies are known. We used this parameter to develop an algorithm for selecting the optimal combination of primers necessary to identify a set of varieties. The optimal combination of primers determined for a small elite group of varieties applied on a larger set induces a risk of confusion involving 1 of the elite varieties. We estimated the risk of confusion using the D value of each primer of the combination. We applied this methodology on a set of 224 varieties of Vitis vinifera screened with 21 RAPD primers and two microsatellite loci. The discriminating power of the primers did not only depend on the number of patterns it generates but also on the frequencies of the different patterns. A combination of 8 primers (6 RAPD and two microsatellite) was found to be optimum for the discrimination of these 224 varieties. A subset of 38 elite varieties was also investigated. The determined optimal combination of 4 primers (3 RAPD and one microsatellite) applied on the 224 varieties gave 9 risks of confusion involving 1 of the elite varieties. Confusion can happen between varieties with the same origin as well as between varieties of very diverse geographical origins.

Notes: Abstract  The dogroses, Rosa sect. Caninae, are polyploid and characterized by their unique meiosis with an unequal number of chromosomes in the male and female gametes. The pollen cells have 7 chromosomes and the egg cells 21, 28 or 35 depending on the ploidy level of the species. The resulting matroclinal inheritance was studied with both morphological and molecular markers in a pair of reciprocal crosses between R. dumalis and R. rubiginosa (2n=35). A canonical discriminant analysis based on seven morphological characters showed only a minor overlapping between the two progeny groups. In addition, the R. dumalis×R. rubiginosa offspring were more heterogeneous than the offspring from the reciprocal cross in each of the characters analysed. Eleven RAPD markers specific for the R. dumalis parent and 10 RAPD markers specific for the R. rubiginosa parent were scored in the offspring. Each of the offspring exhibited either all, or all-but-one, of the seed parent markers. The average number of pollen donor markers found in the offspring was 3.2 (R. dumalis×R. rubiginosa) and 2.7 (R. rubiginosa×R. dumalis). About half of the pollen donor markers were never transmitted to the progeny. This is, to our knowledge, the first time the highly skewed chromosome distribution in Rosa sect. Caninae has been demonstrated with statistically evaluated morphological data and with molecular markers.

Notes: Abstract  We examined the effects of different methods of forest regeneration on the genetic diversity of lodgepole pine (Pinus contorta var ‘latifolia’) using two different DNA-based molecular markers [randomly amplified polymorphic DNA (RAPDs) and microsatellites or simple sequence repeats (SSRs)]. Genetic diversity was estimated for 30 individuals in each of four populations for the following three stand types: (1) mature lodgepole pine (〉100 years); (2) 20- to 30-year-old harvested stands left for natural regeneration; (3) 20- to 30-year-old planted stands (4 stands of each type); and one group of 30 operationally produced seedlings. There was no significant effect of stand type on expected heterozygosity, although allelic richness and diversity were much higher for SSRs than for RAPDs. Expected heterozygosity ranged from 0.39 to 0.47 based on RAPDs and from 0.67 to 0.77 based on SSRs. The number of alleles per locus for SSRs ranged from 3 to 34 (mean 21.0), and there was a significant relationship between sequence repeat length and the number of alleles at a locus. Both marker types showed that over 94% of the variation was contained within the populations and that the naturally regenerated stands sampled had lower (not significant) expected heterozygosity than the planted or unharvested stands. The group of seedlings (assessed by RAPDs only) had expected heterozygosity and allele frequencies similar to those of the unharvested stands. Genetic distance measures were higher than obtained previously in the species using isozyme markers. There was no correlation between the two marker types for pair-wise genetic distances based on populations analyzed by both methods. Pair-wise genetic distance measures and an ordination of allele frequencies for both marker types showed little effect of geographic location or stand type on genetic similarity.

Notes: Abstract  We have developed microsatellite markers (SSRs) applicable to Fagus crenata using the RAHM method and investigated their polymorphisms. We also applied the SSRs in an analysis of a closely related species, F. japonica. Here we describe the isolation and characterization of nine polymorphic microsatellite markers, of which eight are applicable to both species. Among 30 individuals of each of F. crenata and F. japonica we detected a total of 79 and 77 alleles, respectively, with an average of 9.9 and 8.6 alleles per locus. The mean expected heterozygosity (He) was 0.615 (range: 0.216–0.925) in F. crenata and 0.660 in F. japonica (range: 0.259–0.827). The He values were considerably higher than those previously found for isozymes. Paternity exclusion probabilities for multiple loci, calculated over all loci, were extremely high (0.999 and 0.998 in F. crenata and F. japonica, respectively): sufficiently high to study pollen flow in both species.

Notes: Abstract A set of molecular markers to differentiate the aphid (Hemiptera: Aphidoidea) species Sitobion avenae (Fabricius) from Sitobion fragariae (Walker), is presented. These markers correspond to (1) a region of the mitochondrial DNA, (2) five species-specific RAPD banding patterns and (3) four microsatellite loci. Each of the markers was able to clearly distinguish between the species. The utility of each molecular marker is discussed. Mitochondrial DNA is best applicable to species determination and relative abundance, RAPDs to the evaluation of genetic diversity, and microsatellites to the assessment of the population genetic structure; the combined use of mtDNA with the other techniques can be of importance when the presence of hybrids is suspected, and RAPDs with microsatellites are best used together in population genetics and host preference studies.

Notes: Abstract Pieris butterflies (Lepidoptera: Pieridae) are specialist herbivores of cruciferous plants. They exploit glucosinolates, secondary plant metabolites chemotaxonomically characteristic for this plant family, as token stimuli. In addition to particular glucosinolates, some genera of the Cruciferae contain cardenolides, steroidal allelochemicals that act as potent feeding and oviposition deterrents to several Pieris species. We investigated the sensory mechanisms by which these compounds are perceived in larvae. Pieris caterpillars and many other lepidopterous species are endowed with so-called generalist deterrent receptors, that respond to a broad spectrum of secondary plant substances. In Pieris caterpillars we found a second type of deterrent chemoreceptor in maxillary styloconic taste sensilla. This neuron is very sensitive to cardenolides (threshold 0.1–0.3 μM). The generalist deterrent receptor also responds to these substances but its threshold lies at 50–100× higher concentrations. In behavioural preference experiments Pieris brassicae L. caterpillars preferred cardenolide-treated cabbage leaf discs when confronted with a choice between them and a deterrent substance that does not occur in the Brassicaceae. The cardenolides acted as potent deterrents when offered against untreated cabbage leaf discs. This demonstrates that the balance of activity elicited in the two types of deterrent chemoreceptors determines the behavioural decision.

Notes: Abstract Compensatory responses of caterpillars fed low quality food include increased consumption and utilization of essential nutrients. Information about an insect's responses to nutritional challenges from their host plants could benefit weed biological control efforts in the selection and establishment of new agents. The target weed, Pistia stratiotes L. (Araceae) is a floating aquatic plant that has relatively low nitrogen levels which are further diluted with high water content. Efforts to establish the insect Spodoptera pectinicornis (Hampson) (Lepidoptera: Noctuidae) for biological control of P. stratiotes could benefit by examining the nutritional responses of a similar widely established lepidopteran species, Samea multiplicalis (Guenèe) (Lepidoptera: Pyralidae). Larvae of this species were fed leaves of P. stratiotes plants that had been fertilized (NPK) at high and low rates. The leaves of the fertilized plants had a 4.3-fold increase in nitrogen (dry weight) and a 1.6-fold increase in water content. The results suggest that no compensatory increases occurred in larvae fed leaves from the low fertilized plants as no changes were found in fresh mass consumption or nitrogen utilization efficiency. Consequently, development time from second-third instars to pupation was delayed about 3 days compared with larvae fed the high nitrogen leaves. Furthermore, consumption of nitrogen was only 30% and its accumulation into larval tissues was only 60% compared with the larvae fed the high fertilized leaves. The resulting larvae had both a final biomass and a growth rate that were reduced by 40%. Regardless of plant fertilizer level, the larvae fed at a rate 5–10 times greater than that of similar lepidopteran species consuming either low or high quality diets, suggesting that the S. multiplicalis larvae may be functioning at their biological limit for ingesting food.

Notes: Abstract Phytophagous insects which feed on the leaves of herbaceous host plants have to adapt their life histories to the fact that protein nitrogen is usually highest in growing tissues in spring. We monitored field populations of larvae and adults of three chrysomelid species (Galeruca tanaceti (L.) (main host Achillea millefolium (L.) Yarrow), Cassida rubiginosa (Mueller) (main host Cirsium arvense (L.) Scop.) and Oreina luctuosa (Suffrian) (host Centaurea scabiosa (L.)) together with the amount of protein nitrogen of their food resources and host plant biomass. As expected, the development of host quality, measured as concentration of protein nitrogen, and host plant biomass showed inverse trends during the season. The euryphagous G. tanaceti attacks Achillea early and profits from high nitrogen concentrations in the leaves. Occasional overexploitations of local populations of Achillea are compensated by the capacity to move to other host species. In C. rubiginosa, a species with a host range restricted to the Cardueae, the main larval feeding activity is postponed to a period when the nitrogen content of the host leaves had dropped to 50% of its initial value, but when host plant biomass had increased by 30%. In the monophagous O. luctuosa the larval development is synchronized with a still later phase of host phenology, at which the nitrogen content is below 50% but plant biomass has reached its maximum. There seem to be selection factors, which oppose the use of high quality food in spring and which force the latter two species to postpone their larval development to a later time in the year. This could be caused by numerous factors like, for example, mean daytime temperature. Later in the season the larvae have to cope with the low quality of their host plants. They have, however, the advantage of large quantities of food available. A laboratory study with adults and mature larvae of O. luctuosa shows that this species can overcome low levels of protein nitrogen either by selecting younger leaves with higher nitrogen concentrations or by increasing the daily food consumption rate (RCR) on leaves with a low level of nitrogen and by a prolongation of the feeding period. In this way the larvae compensate the effect of lower daily growth rates (RGR) and a lower food conversion index (ECI) on poor food quality: Regardless of the level of protein nitrogen there was no statistically significant difference in total gain of weight during the third-instar feeding period and in the weight at the end of the third larval stage. The three investigated chrysomelids show that there exists a broad spectrum of adaptations to overcome the dilemma of variable food quality.

Notes: Abstract A Y-linked gene (R-gene) in the flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) confer the ability of larvae to survive on types of the plant Barbarea vulgaris R.Br. (Brassicaceae) which are immune to attack by susceptible conspecifics. Two near-isogenic flea beetle lines were developed. The YE-line contained the Y-linked R-gene, and male larvae from this line survived on B. vulgaris. The ST-line did not contain the gene and did not survive on the plant. The YE-line had been developed through 8–9 generations of backcrosses (YE-males with ST-females) and the two lines were considered to be isogenic except for genes located on the Y-chromosome. A single copy of the Y-linked gene is sufficient to transfer a susceptible genotype (ST) into a resistant genotype (YE) which is able to utilize a plant that is immune to attack by specimens without R-genes. The Y-linked gene had no effects on survival on other plant species tested. The gene did not have any effect on developmental times and weights of adult beetles reared on other plants than B. vulgaris. Developmental times of larvae with the Y-linked gene were longer on B. vulgaris than on normal host plants, R. sativus and S. arvensis, but the adults obtained the same size on these plant species. No trade-offs of the Y-linked gene were discovered. The results suggest that the occurrence of the Y-linked gene is a derived trait which has enabled the flea beetle to expand its host plant range. The evolution of a host shift to B. vulgaris seems not to be favoured by the presence of this single gene.

Notes: Summary In a first attempt to explain the evolution of the avian navigational system, Bellrose suggested that compass mechanisms and the ability for true navigation had developed in connection with migration across increasing distances. Yet birds use compasses, the mosaic and the navigational maps even close to home and for homing. This means that those mechanisms must have developed for orientation within the home range, with the necessity to optimize the everyday flights acting as selective pressure. In view of this, any attempt to reconstruct the evolution of the avian navigational system must start out with the non-flying ancestors of birds. Considering the requirements of orientation by landmarks and by using a compass, compass orientation with the help of the magnetic field appears to be the simplest mechanism; consequently, it must be assumed to belong to the most ancient orientation strategies. The magnetic compass is wide-spread among animals, but it appears to function according to different principles among the various groups of vertebrates so that it is unclear whether birds inherited their magnetic compass from their reptilian ancestors or developed a mechanism of their own. The same is true for the sun compass. The crucial role of the magnetic compass in the ontogenetic development of the sun compass might indicate a similar relationship for the phylogenetic development. Over short distances within the home range, orientation based solely on compass orientation appears possible, using the strategy of route reversal, with non-straight routes being integrated. Since this strategy accumulates errors, it becomes inaccurate over longer distances, thus causing selective pressure to use local site-specific information. This leads to the formation of the mosaic map, a mechanism that includes landmarks as well as compass orientation. Today, the mosaic map of landmarks is a mechanism by itself, established according to innate learning principles that associate information on path integration with site-specific information, thus forming a directionally oriented mental representation of the distribution of landmarks. The navigational map is formed by applying the same principles to factors of the nature of gradients; it thus appears to have developed from the mosaic map. Whether or not it is a special development of birds associated with their flying ability is unclear. Because the birds probably inherited the basic mechanisms of orientation from their ancestors, one would expect these mechanisms to be similar in all birds. For the mechanisms involving learned components, this means that they are established following common rules. Birds improved those mechanisms and adapted them to their specific needs. Migration is assumed to have begun with non-directed search movements for regions offering better conditions. At this stage, the already existing mechanisms of homing were sufficient for navigation between the various areas. When these first movements turned into regular migration between two regions, the migratory program began to evolve, starting out with spontaneous tendencies in a preferred direction. The magnetic compass may have served as first reference system for the migratory direction; later, celestial rotation, indicated by the changing pattern of polarized light during the day, obtained its important role in indicating the reference direction geographic South. In the course of time, sophisticated migration programs with changes in direction, controlling time programs, responses to trigger mechanisms etc. developed. The migratory direction and distance, i.e. the amount of migratory activity, continue to be subject to selective pressure so that birds can respond to the environmental conditions in an optimal way. The transition from daytime migration to night migration did not require new mechanisms, as the magnetic compass can be used at any time of the day. Later, however, the star compass evolved, which is to be considered a special development of night-migrating birds, with its way of functioning well adapted to the specific needs of migrants. Birds also developed the ability to derive information on celestial rotation from the rotating stars at night and to transfer this information directly to the star compass. Since migratory habits evolved many times independently among birds, the same has to be assumed for the specific mechanisms of migratory orientation. This means that they need not necessarily be identical in all bird migrants. We are to expect convergent developments, however, leading to mechanisms of the most suitable type.

Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.

Notes: Abstract A philosophically comprehended account is given of the genesis and evolution of the concept of protein. Characteristic of this development were not shifts in theory in response to new experimental data, but shifts in the range of questions that the available experimental resources were fit to cope with effectively. Apart from explanatory success with regard to its own range of questions, various other selecting factors acted on a conceptual variant, some stemming from a competing set of research questions, others from an altogether different field of inquiry, and still others from the external environment. These results are best explained on, hence support, an evolutionary model of the progress of experimental investigation, whose outlines are briefly discussed.

Notes: Abstract A simple procedure for DNA isolation from processed dried commercial samples of tea is described. The method involves a modified CTAB procedure employing extensive washing, use of 1% PVP to remove polyphenolics and a single phenol:chloroform extraction step. The average yield ranges from 164–494 μg/g tea sample for various market samples. The DNA obtained from 11 different brands of tea using this procedure were consistently amplifiable (using both RAPD primers as well as defined sequences as primers) and digestible with restriction endonucleases.

Notes: Abstract A random genomic library of Tunisian date-palm varieties has been built from total cellular DNA, previously amplified according to an RAPD procedure. The resultant recombinant DNA is characterised by a size ranging from 200 to 1600 bp inserts. This DNA would constitute a large number of anonymous probes useful in Southern hybridisation experiments. It would also provide potential markers aimed at the molecular characterisation of date-palm varieties, aid the search of those associated with bayoud disease and suggest a sex determination of trees.

Notes: Abstract Soil organisms play principal roles in several ecosystem functions, i.e. promoting plant productivity, enhancing water relations, regulating nutrient mineralisation, permitting decomposition, and acting as an environmental buffer. Agricultural soils would more closely resemble soils of natural ecosystems if management practices would reduce or eliminate cultivation, heavy machinery, and general biocides; incorporate perennial crops and organic material; and synchronise nutrient release and water availability with plant demand. In order to achieve these goals, research must be completed to develop methods for successful application of organic materials and associated micro-organisms, synchronisation of management practices with crop and soil biota phenology, and improve our knowledge of the mechanisms linking species to ecosystem processes.

Notes: Abstract The genes pcbAB, pcbC and penDE encoding enzymes that catalyze the three steps of the penicillin biosynthesis have been cloned from Penicillium chrysogenum and Aspergillus nidulans. They are located in a cluster in Penicillium chrysogenum, Penicillium notatum, Aspergillus nidulans and Penicillium nalgiovense. The three genes are clustered in chromosome I (10.4 Mb) of P. chrysogenum, in chromosome II of P. notatum (9.6 Mb) and in chromosome VI (3.0 Mb) of A. nidulans. The cluster of the penicillin biosynthetic genes is amplified in strains with high level of antibiotic production. About five to six copies of the cluster are present in the AS-P-78 strain and 11 to 14 copies in the E1 strain (an industrial isolate), whereas only one copy is present in the wild type (NRRL 1951) strain and in the low producer Wis 54-1255 strain. The amplified region in strains AS-P-78 and E1 is arranged in tandem repeats of 106.5 or 57.6-kb units, respectively. In Acremonium chrysogenum the genes involved in cephalosporin biosynthesis are separated in at least two clusters. The pcbAB and pcbC genes are linked in the so-called ‘early cluster’ of genes involved in the cephalosporin biosynthesis. The ‘late cluster’, which includes the cefEF and cefG genes, is involved in the last steps of cephalosporin biosynthesis. The ‘early cluster’ was located in chromosome VII (4.6 Mb) in the C10 strain and the ‘late cluster’ in chromosome I (2.2 Mb). Both clusters are present in a single copy in the A. chrysogenum genome, in the wild-type and in the high cephalosporin-producing C10 strains.

Notes: Abstract Robert Chambers and Thomas Henry Huxley helped popularize science by writing for general interest publications when science was becoming increasingly professionalized. A non-professional, Chambers used his family-owned Chambers' Edinburgh Journal to report on scientific discoveries, giving his audience access to ideas that were only available to scientists who regularly attended professional meetings or read published transactions of such forums. He had no formal training in the sciences and little interest in advancing the professional status of scientists; his course of action was determined by his disability and interest in scientific phenomena. His skillful reporting enabled readers to learn how the ideas that flowed from scientific innovation affected their lives, and his series of article in the Journal presenting his rudimentary ideas on evolution, served as a prelude to his important popular work, Vestiges of the Natural History of Creation. Huxley, an example of the new professional class of scientists, defended science and evolution from attacks by religious spokesmen and other opponents of evolution, informing the British public about science through his lectures and articles in such publications as Nineteenth Century. He understood that by popularizing scientific information, he could effectively challenge the old Tory establishment -- with its orthodox religious and political views -- and promote the ideas of the new class of professional scientists. In attempting to transform British society, he frequently came in conflict with theologians and others on issues in which science and religion seemed to contradict each other but refused to discuss matters of science with non-professionals like Chambers, whose popular writing struck a more resonant chord with working class readers.

Notes: Abstract  HLA-B and C are related class I genes which are believed to have arisen by duplication of a common ancestor. Previous study showed the presence of orthologues for both HLA-B and C in African apes but only for HLA-B in Asian apes. These observations suggested that the primate C locus evolved subsequent to the divergence of the Pongidae and Hominidae. From an analysis of orangutan Tengku two HLA-C-like alleles (Popy C*0101 and Popy C*0201) were defined as well as three HLA-B-like (Popy-B) alleles. By contrast, no Popy-C alleles were obtained from orangutan Hati, although three Popy-B alleles were defined. Thus an HLA-C-like locus exists in the orangutan (as well as a duplicated B locus), implying that the primate C locus evolved prior to the divergence of the Pongidae and Hominidae and is at least 12–13 million years old. Uncertain is whether all orangutan MHC haplotypes contain a C locus, as the failure to find C alleles in some individuals could be due to a mispairing of HLA-C-specific primers with certain Popy-C alleles. These results raise the possibilities that other primate species have a C locus and that the regulation of natural killer cells by C allotypes evolved earlier in primate evolution than has been thought.

Notes: Abstract Previous investigations have revealed a considerable difference between the spectral behavior of a molecule in a pure substance and that in a mixture. To gain more insight into the influence of the intermolecular interaction and of the mass of the molecules, we performed high-resolution measurements of the linewidths and peak positions of the vibrational Raman spectrum of pure nitrogen, nitrogen in argon, and nitrogen in helium. The research was carried out at room temperature and at pressures up to the melting line. It turns out that, in contrast with expectation, the linewidth as well as the frequency shift is essentially the same for pure nitrogen as for nitrogen diluted in argon, although both the mass and the potential well depth are quite different. The experimental results show the same tendency as recent computer simulations.

Notes: Abstract It is commonly argued that the rules of language, as distinct from its semantic features, are the characteristics which most clearly distinguish language from the communication systems of other species. A number of linguists (e.g., Chomsky 1972, 1980; Pinker 1994) have suggested that the universal features of grammar (UG) are unique human adaptations showing no evolutionary continuities with any other species. However, recent summaries of the substantive features of UG are quite remarkable in the very general nature of the features proposed. While the syntax of any given language can be quite complex, the specific rules vary so much between languages that the truly universal (i.e. innate) aspects of grammar are not complex at all. In fact, these features most closely resemble a set of general descriptions of our richly complex semantic cognition, and not a list of specific rules. General principles of the evolutionary process suggest that syntax is more properly understood as an emergent characteristic of the explosion of semantic complexity that occurred during hominid evolution. It is argued that grammatical rules used in given languages are likely to be simply conventionalized, invented features of language, and not the result of an innate, grammar-specific module. The grammatical and syntactic regularities that are found across languages occur simply because all languages attempt to communicate the same sorts of semantic information.

Notes: Abstract Adsorption of N2 on NaY zeolites at 85 K and equilibrium pressures higher than 1 kPa results in the formation of geminal dinitrogen complexes characterized by an IR band at 2333.5 cm−1 (2255.4 cm−1 after adsorption of 15N2). With decreasing equilibrium pressure the complexes tend to loose one N2 ligand, thus forming linear species characterized by an IR band at 2336.8 cm−1 (2258.7 cm−1 after adsorption of 15N2). All species disappear completely after evacuation. Co-adsorption of N2 and CO revealed that the dinitrogen complexes are formed on Na+ cations. The changes in the concentrations of the linear and geminal N2 species with the changes in the equilibrium pressure are excellently described by equations of adsorption isotherms proposed earlier for mono- and di-carbonyls.

Notes: Abstract Carbon and nitrogen stable isotope ratios (δ13C and δ15N) of surface sediments were measured within Osaka Bay, in the Seto Inland Sea in Japan, in order to better understand the sedimentation processes operating on both terrestrial and marine organic matter in the Bay. The δ13C and δ15N of surface sediments in the estuary of the Yodo River were less than −23‰ and 5‰ respectively, but increased in the area up to about 10 km from the river mouth. At greater distances they became constant (giving δ13C of about −20‰ and δ15N about 6‰). It can be concluded that large amounts of terrestrial organic matter exist near the mouth of the Yodo River. Stable isotope ratios in the estuary of the Yodo River within 10 km of the river mouth were useful indicators allowing study of the movement of terrestrial organic matter. Deposition rates for total organic carbon (TOC) and total nitrogen (TN) over the whole of the Bay were estimated to be 63,100 ton C/year and 7,590 ton N/year, respectively. The deposition rate of terrestrial organic carbon was estimated to be 13,200 (range 2,000–21,500) ton C/year for the whole of Osaka Bay, and terrestrial organic carbon was estimated to be about 21% (range 3–34) of the TOC deposition rate. The ratio of the deposition rate of terrestrial organic carbon to the rate inflow of riverine TOC and particulate organic carbon (POC) were estimated to be 19% (range 3–31) and 76% (range 12–100), respectively.

Notes: Abstract Potato-cyst nematodes (Globodera pallida) cause severe yield losses in potato. Plants infected with potato-cyst nematodes generally have reduced concentrations of nitrogen, phosphorus and potassium in the foliage. This study investigated whether reduced growth of nematode-infected potato is caused by nutrient limitation. Experiments in the field and in containers showed that phosphorus concentration correlated best with total crop biomass at early stages of growth. The role of phosphorus in nematode damage was further investigated in the field and in the Wageningen Rhizolab. The experimental field was infested with potato-cyst nematodes and two levels of nematode density were established by fumigation with a nematicide. Prior applications of calcium carbonate resulted in pHKCl levels of 4.8 and 6.1. Two levels of phosphorus fertiliser were applied: either 0 or 225 kg P ha−1. In the Wageningen Rhizolab, soil of both pH levels from the field was used after treatment with 1 MRad gamma irradiation to kill the nematodes. Subsequently, half of the soil was inoculated with cysts to give a nematode density of 30 viable juveniles per gram of soil. In the field, nine weeks after planting, the total crop biomass ranged from 107 g m−2 for the treatment with nematodes at pHKCl 6.1 without phosphorus fertiliser to 289 g m−2 for the fumigated treatment at pHKCl 4.8 with phosphorus fertiliser. The differences in total biomass for the various treatments were explained by differences in foliar phosphorus concentration. Nematodes induced or aggravated P deficiency and reduced total biomass. This was not the only damage mechanism as at high, non-limiting levels of foliar phosphorus concentration, nematodes still reduced total biomass. In the Wageningen Rhizolab, directly after planting, the number of roots visible against minirhizotrons was reduced by nematodes. However, the increase of root number in the nematode treatment continued longer than in the control, until root number was higher than that of the control. The compensary root growth of the nematode treatment was restricted to the top 30 cm and nematodes reduced rooting depth. High soil pH reduced growth, mainly by reducing the availability of phosphate. Both nematodes and high soil pH reduced nutrient uptake per unit root length. Our results lead us to suggest an interaction between nematodes and soil pH, with nematode damage being higher at pHKCl 6.1 than at pHKCl 4.8.

Notes: Abstract It is argued, with selected examples from freshwaterfish systematics, that species should be viewed as anexpression of self-perpetuated clustered variation innature, conforming to the phylogenetic speciesconcept. The importance of species lies in thefunctional and structural significance of theirdiagnostic characters. Species can be nested by theircharacters into a tree diagram (phylogeny) orhierarchical alignment structure (classification) ofcharacter distribution, which may be taken to reflectevolution, the unifying theory of organismaldiversification. The phylogenetic species concept,which emphasizes recognition of a pattern ofvariation, describes better than any other proposedconcept the units called species by systematists.Other concepts are based on processes and normally donot permit recognition of particular taxa. Specieshave unique histories, and speciation may proceed bydifferent mechanisms. Whereas it may be postulatedthat speciation entails an irreversible change in thegenetic structure of taxa, recognized by phenotypicexpression and apparently also maintained to a largeextent by selection for a particular phenotype,species recognition must remain independent ofassumptions about species history and spatialdistribution. Species are monophyletic taxa and thespecies category does not differ significantly inphylogenetic regard from other systematic categories.Species as such are not necessarily evolutionaryunits. It is recommended to apply species names withreference to the diagnostic characters of the speciesand to abandon the type specimen described by theInternational Code of Zoological Nomenclature as anomenclatural reference unit.

Notes: Abstract Adenosine triphosphate (ATP) levels in sperm from chinook salmon (Oncorhynchus tshawytscha) were found to be 12.1±1.9 pmol ATP per 106 sperm cells (mean±SEM, n=18). Sperm were stored at 0–2 °C for up to 72 h under 100, 21, and 0% O2. Changes in sperm ATP content of samples maintained under 100 and 21% O2 were indistinguishable, decreasing to 50% of initial values after 72 h. ATP levels of sperm stored under 0% O2 decreased to 10% of initial values within 8 h and remained unchanged throughout the following 64 h. The initial percent of living sperm (sperm viability) was 94.7±1.7% (mean±SEM, n=12) and was unaltered at 24 h under all O2 tensions. At 72 h, sperm viability remained unchanged under 21% O2 and had decreased by 20% under 100% O2 and by 30% under 0% O2. Therefore, reductions in sperm ATP levels could not be attributed to cell lysis, as viability decreased only modestly over these durations. Fertilizing ability correlated positively with sperm ATP levels. Spermatocrit values increased by 20% for the samples maintained under 100 and 21% O2 after 72 h. However, a 20% increase in spermatocrit occurred within 24 h in samples maintained under 0% O2, rising 70% after 72 h under 0% O2. These data indicate that chinook sperm ATP (1) can be altered and manipulated without significant loss of viability, (2) is positively associated with fertilization, and (3) probably plays a role in sperm packing and cell flexibility.

Notes: Abstract Several lines of evidence suggest that nitrogen in most tropical forests is relatively more available than N in most temperate forests, and even that it may function as an excess nutrient in many tropical forests. If this is correct, tropical forests should have more open N cycles than temperate forests, with both inputs and outputs of N large relative to N cycling within systems. Consequent differences in both the magnitude and the pathways of N loss imply that tropical forests should in general be more15N enriched than are most temperate forests. In order to test this hypothesis, we compared the nitrogen stable isotopic composition of tree leaves and soils from a variety of tropical and temperate forests. Foliar δ15N values from tropical forests averaged 6.5‰ higher than from temperate forests. Within the tropics, ecosystems with relatively low N availability (montane forests, forests on sandy soils) were significantly more depleted in15N than other tropical forests. The average δ15N values for tropical forest soils, either for surface or for depth samples, were almost 8‰ higher than temperate forest soils. These results provide another line of evidence that N is relatively abundant in many tropical forest ecosystems.

Notes: Abstract Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone.

Notes: Abstract The potentials for sequential reduction of inorganic electron acceptors and production of methane have been examined in sixteen rice soils obtained from China, the Philippines, and Italy. Methane, CO2, Fe(II), NO 3 − , SO 4 2− , pH, Eh, H2 and acetate were monitored during anaerobic incubation at 30 °C for 120 days. Based on the accumulation patterns of CO2 and CH4, the reduction process was divided into three distinct phases: (1) an initial reduction phase during which most of the inorganic electron acceptors were depleted and CO2 production was at its maximum, (2) a methanogenic phase during which CH4 production was initiated and reached its highest rate, and (3) a steady state phase with constant production rates of CH4. and CO2. The reduction phases lasted for 19 to 75 days with maximum CO2 production of 2.3 to 10.9μmol d−1 g−1 dry soil. Methane production started after 2 to 87 days and became constant after about 38–68 days (one soil 〉120 days). The maximum CH4 production rates ranged between 0.01 and 3.08μmol d−1 g−1. During steady state the constant CH4 and CO2 production rates varied from 0.07 to 0.30μmol d−1 g−1 and 0.02 and 0.28μmol d−1 g−1, respectively. Within the 120 d of anaerobic incubation only 6–17% of the total soil organic carbon was released into the gas phase. The gaseous carbon released consisted of 61–100% CO2, 〈0.1–35% CH4, and 〈5% nonmethane hydrocarbons. Associated with the reduction of available Fe(III) most of the CO2 was produced during the reduction phase. The electron transfer was balanced between total CO2 produced and both CH4 formed and Fe(III), sulfate and nitrate reduced. Maximum CH4 production rate (r=0.891) and total CH4 produced (r =0.775) correlated best with the ratio of soil nitrogen to electron acceptors. Total nitrogen content was a better indicator for “available” organic substrates than the total organic carbon content. The redox potential was not a good predictor of potential CH4 production. These observations indicate that the availability of degradable organic substrates mainly controls the CH4 production in the absence of inorganic electron acceptors.

Notes: Abstract Explaining the nearly ubiquitous absence of nitrogen fixation by planktonic organisms in strongly nitrogen-limited estuaries presents a major challenge to aquatic ecologists. In freshwater lakes of moderate productivity, nitrogen limitation is seldom maintained for long since heterocystic, nitrogen-fixing cyanobacteria bloom, fix nitrogen, and alleviate the nitrogen limitation. In marked contrast to lakes, this behavior occurs in only a few estuaries worldwide. Primary production is limited by nitrogen in most temperate estuaries, yet no measurable planktonic nitrogen fixation occurs. In this paper, we present the hypothesis that the absence of planktonic nitrogen fixers from most estuaries is due to an interaction of bottom-up and top-down controls. The availability of Mo, a trace metal required for nitrogen fixation, is lower in estuaries than in freshwater lakes. This is not an absolute physiological constraint against the occurrence of nitrogen-fixing organisms, but the lower Mo availability may slow the growth rate of these organisms. The slower growth rate makes nitrogen-fixing cyanobacteria in estuaries more sensitive to mortality from grazing by zooplankton and benthic organisms. We use a simple, mechanistically based simulation model to explore this hypothesis. The model correctly predicts the timing of the formation of heterocystic, cyanobacterial blooms in freshwater lakes and the magnitude of the rate of nitrogen fixation. The model also correctly predicts that high zooplankton biomasses in freshwaters can partially suppress blooms of nitrogen-fixing cyanobacteria, even in strongly nitrogen-limited lakes. Further, the model indicates that a relatively small and environmentally realistic decrease in Mo availability, such as that which may occur in seawater compared to freshwaters due to sulfate inhibition of Mo assimilation, can suppress blooms of heterocystic cyanobacteria and prevent planktonic nitrogen fixation. For example, the model predicts that at a zooplankton biomass of 0.2 mg l−1, cyanobacteria will bloom and fix nitrogen in lakes but not in estuaries of full-strength seawater salinity because of the lower Mo availability. Thus, the model provides strong support for our hypothesis that bottom-up and top-down controls may interact to cause the absence of planktonic nitrogen fixation in most estuaries. The model also provides a basis for further exploration of this hypothesis in individual estuarine systems and correctly predicts that planktonic nitrogen fixation can occur in low salinity estuaries, such as the Baltic Sea, where Mo availability is greater than in higher salinity estuaries.

Notes: Abstract The potentials for sequential reduction of inorganic electron acceptors and production of methane have been examined in sixteen rice soils obtained from China, the Philippines, and Italy. Methane, CO2, Fe(II), NO 3 - , SO 4 2 , pH, Eh, H2 and acetate were monitored during anaerobic incubation at 30 °C for 120 days. Based on the accumulation patterns of CO2 and CH4, the reduction process was divided into three distinct phases: (1) an initial reduction phase during which most of the inorganic electron acceptors were depleted and CO2 production was at its maximum, (2) a methanogenic phase during which CH4 production was initiated and reached its highest rate, and (3) a steady state phase with constant production rates of CH4 and CO2. The reduction phases lasted for 19 to 75 days with maximum CO2 production of 2.3 to 10.9 μmol d-1 g-1 dry soil. Methane production started after 2 to 87 days and became constant after about 38--68 days (one soil 〉120 days). The maximum CH4 production rates ranged between 0.01 and 3.08 μmol d-1 g-1. During steady state the constant CH4 and CO2 production rates varied from 0.07 to 0.30 μmol d-1 g-1 and 0.02 and 0.28 μmol d-1 g-1, respectively. Within the 120 d of anaerobic incubation only 6--17% of the total soil organic carbon was released into the gas phase. The gaseous carbon released consisted of 61--100% CO2, 〈0.1--35% CH4, and 〈5% nonmethane hydrocarbons. Associated with the reduction of available Fe(III) most of the CO2 was produced during the reduction phase. The electron transfer was balanced between total CO2 produced and both CH4 formed and Fe(III), sulfate and nitrate reduced. Maximum CH4 production rate (r = 0.891) and total CH4 produced (r = 0.775) correlated best with the ratio of soil nitrogen to electron acceptors. Total nitrogen content was a better indicator for “available” organic substrates than the total organic carbon content. The redox potential was not a good predictor of potential CH4 production. These observations indicate that the availability of degradable organic substrates mainly controls the CH4 production in the absence of inorganic electron acceptors.

Notes: Abstract Earlier related to parasitic elements, retrotransposons of eukaryotes have been demonstrated to participate in general cell processes such as chromosome repair and evolution of gene expression (Teng et al., 1996; McDonald, 1993). Here, we report the existence of two class of genomic copies of retrotransposon 1731 with different expression strategies, one of which might be driven by natural selection. The first class uses conventional translation frameshifting known to ensure expression of revere transcriptase (RT) open reading frame (ORF), depending on the efficiency of frameshifting. The bulk of genomic copies are related to the second class where the frameshift is prevented as a result of the substitution of a rare codon recoginsing rare tRNA by a codon preferred by host genome, whereas the RT ORF is restored by downstream single nuclotide deletion. We suggest that natural selection has driven the switching of 1731 expression strategy from retrovirus-like to the fussion-ORF expression. This observation is in accordance with the detection in testes of fused Gag-RT polypetide encoded by 1731. The abundance of RT in testes may serve for normal development of host tissue.

Notes: Abstract The distribution of the three friendly close-range vocalization types known in the Felidae was plotted on a recently published phylogeny of the cat family (Felidae) based on sequence comparisons of two mitochondrial DNA genes and other molecular and biochemical characters, with extrapolated divergence ages of its various lineages. It was found to be congruent with this phylogeny. One of the sound types is likely to be present in 30 species of the family (documented in 22 so far), another is present in 4, and the third in 2 species only; these sound types represent a phylogenetic transformation series. The latter two vocalization types also differ considerably from the first in the mode of sound production. From this, evolutionary conservatism over a long epoch for the one widespread vocalization type can be inferred, and less conservatism in the type present in four species, while the emergence of the least common type is evidence of relatively considerable and rapid evolutionary change. Thus, acoustic communication signals in a group of taxa can evolve at considerably different rates, and for a specific character this rate can differ between different lineages of that group. The ultimate causes of the evolutionary stability or of the subsequent relatively rapid change in sound structure and mode of sound production in these felid vocalizations are unknown.

Notes: Abstract Are there general principles for pattern generation? We examined this question by analyzing the operation of large populations of evolved model central pattern generators (CPGs) for walking. Three populations of model CPGs were evolved, containing three, four, or five neurons. We identified six general principles. First, locomotion performance increased with the number of interneurons. Second, the top 10 three-, four-, and five-neuron CPGs could be decomposed into dynamical modules, an abstract description developed in a companion article. Third, these dynamical modules were multistable: they could be switched between multiple stable output configurations. Fourth, the rhythmic pattern generated by a CPG could be understood as a closed chain of successive destabilizations of one dynamical module by another. A combinatorial analysis enumerated the possible dynamical modular structures. Fifth, one-dimensional modules were frequently observed and, in some cases, could be assigned specific functional roles. Finally, dynamic dynamical modules, in which the modular structure itself changed over one cycle, were frequently observed. The existence of these general principles despite significant variability in both patterns of connectivity and neural parameters was explained by degeneracy in the maps from neural parameters to neural dynamics to behavior to fitness. An analysis of the biomechanical properties of the model body was essential for relating neural activity to behavior. Our studies of evolved model circuits suggest that, in the absence of other constraints, there is no compelling reason to expect neural circuits to be functionally decomposable as the number of interneurons increase. Analyzing idealized model pattern generators may be an effective methodology for gaining insights into the operation of biological pattern generators.

Notes: Abstract Recent molecular studies revealed nine to ten gene products involved infunction/assembly of the methanoarchaeal ATPase and unravel a closerelationship of the A1A0-ATPase and theV1V0-ATPase with respect to subunit composition and thestructure of individual subunits. Most interestingly, there is anastonishing variability in the size of the proteolipids in methanoar chaealA1A0-ATPases with six, four, or two transmembranehelices and a variable number of conserved protonizable groups per monomer.Despite the structural similarities the A1A0-ATPasediffers fundamentally from the V1V0-ATPase by itsability to synthesize ATP, a feature shared withF1F0-ATPases. The discovery of duplicated andtriplicated versions of the proteolipid in A1A0-ATPsynthases questions older views of the structural requirements for ATPsynthases versus ATP hydrolases and sheds new light on the evolutionof these secondary energy converters.

Notes: Abstract A 2n = 14 karyotype is shared by some species in each of the marsupial orders in Australian and American superfamilies, suggesting that the ancestral marsupial chromosome complement was 2n = 14. We have used chromosome painting between distantly related marsupial species to discover whether genome arrangements in 2n = 14 species in two Australian orders support this hypothesis. Cross-species chromosome painting was used to investigate chromosome rearrangements between a macropodid species Macropus eugenii (2n = 16) and a wombat species in a different suborder (Lasiorhinus latifrons, 2n = 14), and a dasyurid species in a different order (Sminthopsis macroura, 2n = 14). We demonstrate that many chromosome regions are conserved between all three species, and deduce how the similar 2n = 14 karyotypes of species in the two orders are related to a common ancestral 2n = 14 karyotype.

Notes: Abstract Our long range interracial hybridization experiments between a pair of cross fertile races, Drosophila nasuta (2n = 8) and D.albomicans (2n = 6) have resulted in the evolution of two new karyotypic strains under laboratory conditions, which are named as Cytorace 1 and Cytorace 2. These Cytoraces harbor chromosomes from both parents. Here, we compare the body size of the parental races and newly evolved Cytoraces and the relationship between the body size and fitness. Analysis reveals that the parental races have reduced fertility and are larger in body size than newly evolved Cytoraces. Thus, the newly evolved Cytoraces show reduced body size and better fitness in the course of their evolution.

Notes: Abstract The evolution of transposable element structures can be analyzed in populations and species and by comparing the functional domains in the main classes of elements. We begin with a synthesis of what we know about the evolution of the mariner elements in the Drosophilidae family in terms of populations and species. We suggest that internal deletion does not occur at random, but appears to frequently occur between short internal repeats. We compared the functional domains of the DNA and/or amino acid sequences to detect similarities between the main classes of elements. This included the gag, reverse transcriptase, and envelope genes of retrotransposons and retroviruses, and the integrases of retrotransposons and retroviruses, and transposases of class II elements. We find that each domain can have its own evolutionary history. Thus, the evolution of transposable elements can be seen to be modular.

Notes: Abstract We have applied the technique of random amplification of polymorphic DNA (RAPD) to the analysis of the relationships among four species of brine shrimp: Artemia franciscana, A. urmiana, A. sinica, and A. parthenogenetica. Seventy ten-base synthetic oligonucleotides were used to amplify a total of 458 distinct fragments. DNA polymorphisms were found in all the species examined; the highest percentage of polymorphic bands was found in A. parthenogenetica, with 28.8 per cent. Each species was scored for the presence or absence of every amplification product and the data entered into a binary data matrix. Cluster analysis was then performed to create a dendrogram using UPGMA by the NTSYS program. There are significant differences between bisexual species and parthenogenetic populations. A. parthenogenetica provided 94 specific molecular markers, while bisexual species gave 27 specific molecular markers. A. sinica is a species distinct from the other Old World bisexual species.

Notes: Abstract Phytophthora cinnamomi isolates from South Africa and Australia were compared to assess genetic differentiation between the two populations. These two populations were analysed for levels of phenotypic diversity using random amplified polymorphic DNAs (RAPDs) and gene and genotypic diversity using restriction fragment length polymorphisms (RFLPs). Sixteen RAPD markers from four decanucleotide Operon primers and 34 RFLP alleles from 15 putative loci were used. A few isolates from Papua New Guinea known to posses alleles different from Australian isolates were also included for comparative purposes. South African and Australian P. cinnamomi populations were almost identical with an extremely low level of genetic distance between them (Dm=0.003). Common features for the two populations include shared alleles, low levels of phenotypic/genotypic diversity, high clonality, and low observed and expected levels of heterozygosity. Furthermore, relatively high levels of genetic differentiation between mating type populations (Dm South Africa=0.020 and Dm Australia=0.025 respectively), negative fixation indices, and significant deviations from Hardy–Weinberg equilibrium, all provided evidence for the lack of frequent sexual reproduction in both populations. The data strongly suggest that both the South African and Australian P. cinnamomi populations are introduced.

Notes: Abstract Aposematic animals use anti-predator defence mechanisms such as distastefulness coupled with distinctive odours, sounds, or colour visual signals to predation from domestic chicks we show that the protective value of such visual warning displays is enhanced by increasing size of the signal pattern elements and decreased by pattern asymmetry. These results provide the first experimental evidence that predation may select for individual symmetry of visual warning displays, and concur with earlier demonstrations that asymmetric signals are more difficult to detect, learn, and remember, compared to symmetric signals. Collectively, our findings suggest that prey species possessing warning coloration should be subjected to selection for large and symmetric pattern elements.

Notes: Abstract Different habitat preferences in animals have been interpreted mostly as a result of different adaptive design of the species and/or as a result of interspecific competition. We propose an alternative view of evolution of habitat preferences. Our model is based on progressive stochastic acquisition of cognitive clues discriminating habitat features which correlate with expected fitness. We assume that acquisition of each cognitive clue allowing discrimination of ‘better’ and ‘worse’ habitats (according to the average fitness in each habitat) will constrain further evolution, because each further clue will discriminate habitats only within previously acquired preferences. Simple simulation model shows that if it is the case, even the species with equal habitat-related fitness differences will rapidly diversify in their habitat preferences. Therefore, similarly as in the evolution of other species-specific traits, the evolution of animal–habitat relationship may be strongly affected by stochastic events and historical contingency.

Notes: Abstract Bioluminescence most likely evolved under selection from the visually guided behaviours of co-occurring organisms, in particular that of predators. Many possible functions of light signals have been proposed and some are supported, but whatever their function may be, they make an easy target of the emitter unless it is defended. Therefore, we want to emphasise that in many cases bioluminescence can only have evolved through a defensive function. If this were the case, one would expect multimodal adaptiveness of luminescence with at least some evidence for a defensive function. Light signals could be used in many ways to reduce predation, but for spontaneous glowing species in particular, aposematism seems the only functional strategy. In a preliminary experiment with glowing and non-glowing dummy prey, we found that wild-caught toads discriminated against glowing prey. They showed significantly lower attack responses and higher latencies towards glowing prey dummies. However, some of the toads were less reluctant because they did not distinguish initially between prey with or without the light stimulus. Since the toads were collected in areas abundant with lampyrid glow-worms, which is the only luminous organism at this locality, and our results concur with the general evidence that they may have had previous experiences with this prey, we attribute the result to luminescent aposematism. From the literature, and from our own experiments, we know that toads and many other potential predators experience lampyrids as disagreeable prey. In future experiments we will test whether glow-worms are defended by luminescent aposematism or not.

Notes: Abstract In this paper I argue that the nature of mimetic relationships remains contentious because there are insufficient data to enable full evaluation of theoretical models. There is, however, a growing appreciation of the need to draw together empirical studies to provide foundations for theoretical work. I review some recent data that considers the responses of predators to changing numbers of defended prey items and the nature of mimicry along a palatability spectrum. A simple model of predator behaviour is constructed which combines assumptions from Pavlovian learning studies with traditional ‘number dependent’ learning models. This model has two important properties. First it shows that Pavlovian assumptions can be represented in a simple model which generates interesting predictions. Second it indicates some areas that still need detailed empirical study – most importantly perhaps is the way that predators respond to prey with different levels of edibility.

Notes: Abstract Crinipellis perniciosa (Stahel) Singer is the causal agent of witches' broom disease in the Sterculiaceae, Solanaceae, and Bixaceae families. The disease is endemic to the Brazilian Amazon, and was first reported infecting Theobroma cacao (cocoa) in the State of Bahia, Brazil, in 1989. Random amplified polymorphic DNA (RAPD) analyses were performed on 46 isolates of C. perniciosa from cocoa that were collected from 15 counties in Bahia and the Brazilian Amazon. A total of 258 RAPD loci from 20 primers and three mixed primers were analyzed. Of these loci, 108 (42%) were polymorphic, with an average of 4.7 polymorphic loci per primer produced. Genetic similarities were estimated using Nei and Li's index and UPGMA clustering. Bootstrap analysis divided the phenogram into four significantly different clusters: two groups contained isolates from Ariquemes and from Ouro Preto, Rondônia, and the other two separated the isolates from Bahia into two major groups of C. perniciosa, classified as Group 1 (G1) and Group 2 (G2). The two groups of isolates from Bahia differed for their genetic similarity with the isolates from the Brazilian Amazon. The geographic distribution of the groups in Bahia suggests two independent focal points of introduction. Ongoing programs to screen for resistant cocoa genotypes should consider both groups of isolates.

Notes: Abstract This paper addresses the question of how much biodiversity is enough in the context of the concept of agriculture as a mimic of nature. Following an historical review of the likely origins of ecosystems I show that the currently accepted components of biodiversity, viz. genetic, species and ecosystem, and their functional expression, are relevant to agriculture. Examples of adequate biodiversity are given and it is concluded that what constitutes enough biodiversity in an agricultural system is dependent upon the goal in question and will be different depending on whether the aim is, for example, to increase yield stability or deal with salinity, ground water levels, soil erosion, leaching of nutrients or weed control. The point is made that ecosystems and their composition are contingent in nature so the history of events, their frequency and intensity all need to be considered when interpreting the natural biodiversity present and thus determining what is enough in particular circumstances.

Notes: Abstract This study investigates how the course of evolutionary change of an organismal pattern is canalized by organismal properties. As an example we use the mechanisms of indirect sperm transfer of some microarthropod groups. Miniaturized droplet spermatophores, characterized by a rather similar pattern of structural and functional components, are shown to have evolved independently in the Acari–Actinotrichida and the Pseudoscorpiones within the Arachnida and in the Entognatha (Collembola and Diplura–Campodeoidea), Symphyla, Pauropoda and Pselaphognatha within the Antennata. At least in the phylogenetic lineages leading to the various antennatan groups, evolution of miniaturized spermatophores took place in a similar sequence of transformation steps. It is likely that – originally – large sac spermatophores with a rigid sheath were deposited on the ground. The subsequent sequence of evolution involved carrying structures, a viscous sheath of the spermatophore-droplets, a stable water balance of the spermatophore under habitat conditions and miniaturized spermatophore droplets with immobilized sperm cells. Finally, mate dissociation became a common mode of behaviour in all groups mentioned. Each of the transformation steps was not only an adaptation to a particular selective condition, but additionally a precondition for further adaptive innovation. In this way the sequence of evolutionary change was rigidly determined. Moreover, integration of subsequently evolved components of the spermatophores into a complex network of interacting components obviously caused constraints of interaction, which in turn have caused a remarkable evolutionary stability of the character patterns. Using water mites as an example, it is shown how in a changed environment few behavioural changes have initiated an evolutionary sequence which has finally led convergently in several lineages to semi-direct or direct sperm transfer and to a massive repatterning of the original reproduction pattern. © Rapid Science Ltd. 1998

Notes: Abstract The objective of this work was to study the effect of NK fertilization levels and canopy height on the resistance of Lycopersicon hirsutum and Lycopersicon esculentum to Aculops lycopersici (Acari: Eriophydae). The effects of NK fertilization levels and canopy height in the leaf size and density of trichomes and their effects on tridecan-2-one (2-TD) and undecan-2-one (2-UD) limiting the attack of A. lycopersici on tomato plants were assessed. Different NK fertilization levels had no effect on the resistance of L. hirsutum to A. lycopersici. No significant differences were found in attack rates of this mite on leaves of the top and median parts of L. hirsutum canopy. The type and density of trichomes were the main determining factor of A. lycopersici attack on tomato plants. High trichome densities and type VI glandular trichomes which produce tridecan-2-one are important resistance factors on tomato plants. L. hirsutum showed a high resistance level to A. lycopersici due to high densities of type VI glandular trichomes and consequently higher levels of tridecan-2-one in its leaves.

Notes: Abstract The initial structure of a comet nucleus is most probably a homogeneous, porous, fine-grained mixture of dust and ices, predominantly water. The water ice is presumably amorphous and includes considerable fractions of occluded gases. This structure undergoes significant changes during the early evolution of the nucleus at large heliocentric distances, due to internal radiogenic heating. Structural changes occur mainly as a result of gas flow through the porous medium: the gas pressure that builds up in the interior is capable of breaking the fragile structure and altering the pore sizes and porosity. These effects are modeled and followed numerically, testing a large number of parameters.

Notes: Abstract Nutrient and hydrologic cycles in harvested native forests in southern Australia are largely balanced. For example, we have little or no evidence of any decline in nutrient capital or availability in harvested forests. Short-term and small-scale reductions in evapotranspiration due to loss of leaf area after harvesting are adequately balanced at the landscape scale by large areas of regenerating or older-age forest. In contrast, agricultural systems on similar soils are a) dependent on large inputs of fertilisers to maintain growth and b) frequently subject to increasing salinity and waterlogging or other forms of degradation. The large-scale replacement of long-lived communities of perennial and often deep- rooting native species with annual crops or other communities of shallow-rooting species might be better managed within the framework of knowledge developed from studies of native plant communities. However, application of such a mimic concept to systems of low natural productivity is limited when agricultural systems require continued high productivity. Nonetheless, the mimic concept may help in developing sustainable management of agriculture on marginal lands, and contribute to the nutritional resilience of agroecosystems. Relevant characteristics for mimic agroecosystems in south western Australia include: high species diversity, diversity of rooting attributes, utilisation of different forms of nutrients (especially of N and P) in space and time, and the promotion of practices which increase soil organic matter content.

Notes: Abstract Phenanthrene mineralization rates were found to vary widely among four soils; differences in soil nutrient levels was one hypothesis to explain this variation. To test this hypothesis, phenanthrene mineralization rates were measured in these soils with, and without, added nitrogen and phosphorus. Mineralization rates either remained unchanged or were depressed by the addition of nitrogen and phosphorus. Phenanthrene degradation rates remained unchanged in the soil which had the highest indigenous levels of nitrogen and phosphorus and which showed the largest increase in phosphorus levels after nutrients were added. The soils in which degradation rates were depressed had lower initial phosphorus concentrations and showed much smaller or no measurable increase in phosphorus levels after nutrients were added to the soils. To understand the response of phenanthrene degradation rates to added nitrogen and phosphorus, it may be necessary to consider the bioavailability of added nutrients and nutrient induced changes in microbial metabolism and ecology.

Notes: Abstract The marriage of chemistry with ecology has been a productive one, providing a wealth of examples of how chemicals play important roles in the loves and lives of living organisms. At first the marriage may have been a simple and monogamous one with the major scientific aim of making proximate analyses of chemically mediated, individual level interactions. But times have changed and chemical ecology is broadening, embracing different approaches and disciplines. There is, for example, increasing appreciation of variability in the systems under study and an increase in evolutionary thinking. Another promising development is greater recognition of the potential importance of chemically mediated interactions for population dynamics and for structuring communities and species coexistence. The latter is an utterly underexplored area in chemical ecology. The field of chemical ecology of insect parasitoids shows some of these promising developments. Responses of parasitoids to infochemicals are increasingly studied with an integrated approach of mechanism and function. This integration of “how” and “why” questions significantly enhances the evolutionary and ecological understanding of stimulus–response patterns. The future challenge in chemical ecology is to demonstrate how chemically mediated interactions steer ecological and evolutionary processes at all levels of ecological organization. To reach this goal there is a need for interdisciplinary collaboration among chemists and ecologists working at different levels of organization and with different approaches, with other disciplines as partners.

Notes: Abstract Results of an agent-based computer simulation of the evolution of diploid sexual organisms showed that several mate selection strategies confer much higher average fitness to the simulated populations, and higher evolutionary stability to the alleles coding for these strategies, than random mating. Strategies which select for 'good genes' were very successful, and so were strategies based on assortative mating. The results support the hypothesis that mating is not likely to be random in nature and that the most successful mate selection strategies are those based on assortative mating or on advantageous genes.

Notes: Abstract Three approaches to nitrogen budgeting were developed and their ability to quantitatively describe nitrogen cycling in a fertilizer based and a grass–clover based beef system tested. Budgets ranged in complexity from the Economic Input:Output (EIO) budget, which accounted simply for purchases and sales of nitrogen over the farmgate, through the Biological Input:Output (BIO) budget, which included estimates of biological nitrogen fixation and attempted to partition losses into leaching and gaseous forms, to the Transfer:Recycle:Input:Output (TRIO) budget, which also accounted for key soil processes. Nitrogen unaccounted for in the fertilized system decreased with increasing budget complexity (285, 212 and 188 kg ha-1 yr-1 unaccounted for by the EIO, BIO and TRIO budgets, respectively). In the legume based grass–clover system, the EIO budget did not accurately describe total nitrogen inputs as it did not include 146 kg ha-1 yr-1 from symbiotic nitrogen fixation. In the grass–clover system, nitrogen unaccounted for was again greater using the BIO than the TRIO budget (103 and 79 kg ha-1 yr-1, respectively). In conclusion, the most complex budgeting approach (TRIO) was able to account for the fate of a greater proportion of nitrogen inputs than the simpler approaches. However, the perceived success of the different approaches was strongly dependent on the precise objective.

Notes: Abstract Acidification of cattle slurry with nitric acid to pH 4.5 was studied on experimental dairy farms in the Netherlands as a measure to reduce ammonia losses. This paper presents the results of two field experiments, carried out to assess the utilization of nitrogen (N) from nitric acid treated cattle slurry following surface application to grassland. Three aspects were studied: (i) the utilization of N from nitric acid treated cattle slurry following a single surface application to grassland; (ii) the effects of multiple applications of nitric acid treated cattle slurry on N utilization, residual inorganic N in the soil and sward quality; and (iii) the residual effects of nitric acid treated slurry on DM and N yield. In these experiments undiluted acidified slurry (UAS) and diluted acidified slurry (DAS) were compared with calcium ammonium nitrate (CAN). Apparent N recoveries (ANR) and apparent N efficiencies (ANE) were calculated on the basis of inorganic N in applied fertilizer and slurries. Following single applications of UAS and CAN on the sward on the clay soil, the average ANR values of UAS and CAN were 0.74 and 0.75 kg kg-1, respectively. The average ANE values of UAS and CAN were 30.3 and 29.5 kg DM per kg N, respectively. Single applications of DAS and CAN on the sandy soil resulted in average ANR values of 0.65 and 0.84 kg kg-1 and average ANE values of 24.1 and 29.2 kg DM per kg N for DAS and CAN, respectively. On average, the direct ANR values after four successive applications of CAN, UAS or DAS were 0.82, 0.82 and 0.74 kg kg-1, respectively and the direct ANE values were 28.4, 27.8 and 27.0 kg DM per kg N. On the sandy soil, the amount of residual inorganic N in the soil after the 4th cut increased with increasing rates of inorganic N application, with a slightly higher amount on plots treated with acidified slurry than on plots fertilized with CAN. On the clay soil, the amount of residual inorganic N was not affected by N application rate nor N source. On average, the residual ANR values, in the unfertilized 5th and 6th cuts, of CAN, UAS or DAS were 0.08, 0.10 and 0.09 kg kg-1, respectively and the residual ANE values were 2.7, 3.3 and 3.0 kg DM per kg N. It was concluded that nitric acid treated cattle slurry is an effective N fertilizer on grassland and that the residual effect of nitric acid treated cattle slurry is only marginally higher than that of CAN. Repeated applications of nitric acid treated cattle slurry did not affect sward composition.

Notes: Abstract Biomass and nitrogen in the roots, rhizomes, stem bases and litter of reed canarygrass (Phalaris arundinacea L.) were repeatedly estimated by soil coring, and root growth dynamics of this potential energy crop was studied for two years using minirhizotrons. Results are discussed in relation to above-ground biomass and nitrogen fertilisation. Five treatments were used: C0, unfertilised control; C1, fertilised with solid N fertiliser in spring; I1, irrigated daily, fertilised as in C1; IF1 , irrigated as I1 and fertilised daily through a drip-tube system; IF2, as in IF1 but with higher N fertiliser rates. Biomass of below-ground plant parts of reed canarygrass increased between the first and second years. Up to 50% of total plant biomass and nitrogen were recovered below-ground. The highest proportions were found in C0. The calculated annual input via root turnover ranged between 80 and 235 g m-2. In absolute terms, up to 1 kg and 10 g m-2 of biomass and nitrogen, respectively, were found in below-ground plant fractions. High inputs of stubble and accumulated below-ground biomass will occur when the ley is ploughed, which will result in a highly positive soil carbon balance for this crop in comparison with that of conventional crops such as cereals.

Notes: Abstract A field experiment was carried out for two consecutive seasons 1994/95 and 1995/96 at ElRwakeeb (a sandy clay loam) to study the effect of Rhizobium sp. (Cicer) inoculation and N fertilization on six chickpea cultivars (Baladi, Gabel marra, NEC 25–27, NEC 2010, ILC 1919, and Flip 85–108). Plants were either inoculated with three Rhizobium sp. (Cicer) strains (TAL 480, TAL 620 and TAL 1148) separately, or N fertilized (50 kg N ha-1). The results of the two seasons indicated the absence of infective strains for chickpea in the soil. Rhizobium inoculation or N fertilization significantly increased the total nodule number per plant, 100 seed weight, yield and protein content of seeds. The results indicated that the three Rhizobium strains are infective and effective in nitrogen fixation. Inoculation with Rhizobium strain TAL 1148 resulted in a significant increment in most of the parameters studied, compared to other strains and untreated control. Cultivar ILC 1919 was the best yielding cultivar, whereas, cultivar NEC 2010 contained the highest protein content, however cultivar Gabel marra showed the highest amount of protein due to inoculation or N fertilization, in the two seasons. Inoculation with Rhizobium strain TAL 1148 increased yield by 72 and 70%, whereas, 50 kg N ha-1 increased it by 70 and 69% in the first and second seasons, respectively. The amounts of protein accumulated (kg ha-1) due to N or Rhizobium inoculation were determined for all cultivars. The results obtained from the inoculation were comparable to those of 50 kg N ha-1.

Notes: Abstract Algal N labelled with 15N added to a flooded soil in laboratory columns without plants was studied to determine the changes over time in the fate of N assimilated by algae and to study how its fate is affected by (a) exclusion of light simulating complete closure of the rice canopy, and (b) addition of fertilizer-NH4 *. In the light but with no added fertilizer-N there was little net mineralization of the added algal N during the first 4 weeks, but after 8 weeks 42% had been mineralized, of which 95% was denitrified. Exclusion of light caused net mineralization to proceed more rapidly in the first 4 weeks due to the death of algal cells and lowered reassimilation. After 8 weeks 51% had been mineralized, of which 54% was denitrified, 16% volatilized and 30% was present as KCl exchangeable NH4 +-N. Application of fertilizer-NH4 + apparently caused mineralization of 25% of the algal N within one week but the results were probably affected by pool substitution in which labelled N mineralized to NH4 +-N was diluted with fertilizer – NH+ 4 and then immobilized leaving more labelled NH4–N in the mineral pool. After 8 weeks, 42% of algal N had been mineralized, of which 69% was estimated to have been denitrified, 19% lost through NH3 volatilization and 12% remained as extracted NH4 ++NO- 3. Uptake of N by a rice crop would reduce the gaseous losses. Algal N was mineralized quickly enough to be available during the growing season of a rice crop and, depending on field conditions, algae may have a role in assimilating N and protecting it from loss as well as being a major driving force for NH3 volatilization through diurnal increases in pH.

Notes: Abstract The recovery of soil mineral nitrogen (N) by crops, and its subsequent utilisation for dry matter (DM) production may be increased when the application of N is postponed until after crop emergence. The significance of this strategy for silage maize was studied in nine field experiments on Dutch sandy soils from 1983 to 1988. In five experiments the effect of slurry applied before planting at a rate of circa 66 m3 ha-1, was compared to the effect of a similar rate of which half was applied before planting and half at the 4–6 leaf stage. In the 4-6 leaf stage slurry was either injected or banded. In four other experiments the effect of mineral fertilizer-N splitting was studied. In these experiments, 30 m3 ha-1 cattle slurry, applied before planting, was supplemented with mineral fertilizer-N at rates ranging from 40 to 160 kg ha-1, either fully applied before crop emergence or split. When split, 40 kg ha-1 of the mineral fertilizer-N rate was banded at the 4–6 leaf stage. According to balance sheet calculations, substantial losses of slurry N and mineral fertilizer-N occurred during the growing season. Losses were compensated for, however, by apparent mineralization, ranging from 0.34 to 0.77 kg N ha-1 day-1. Split applications of cattle slurry had a significant positive effect on the DM yield in two out of five experiments compared to the conventional non-split application, but only when the post-emergence slurry application was banded which is no longer in accordance with present legislation. Split applications of mineral fertilizer-N had a significant positive effect in one experiment where rainfall was excessive but not in the others. The results provide insufficient evidence to recommend farmers to split applications. Soil mineral N sampling at the 4–6 leaf stage should hence be considered a control on the appropriateness of early N applications after exceptional weather conditions rather than a routine observation on which the post-emergence N dressing is to be based in a deliberate splitting strategy. Our data suggest that the financial return of a 40 kg ha-1 supplementation with mineral fertilizer-N, was questionable when more than 175 kg N ha-1 were found in the upper 0.6 m soil layer at the 4–6 leaf stage.

Notes: Abstract A Spring Wheat crop was grown using three irrigation levels and nitrogen rate applications to evaluate chlorophyll meter measurements as a possible nitrogen nutrition index for modelling. These measurements yielded the most reliable indications at Zadoks GS45. The lower limit indicating severe nitrogen deficiency in the leaves was approximately 35 SPAD units while the upper limit of 45 SPAD units, indicated an excess consumption.

Notes: Abstract One principal function of biological molecules in bacteria is to recognize other molecules. This allows cells to assemble for regulated enzymatic catalysis and the integration of biochemical pathways. Recognition is also an essential and a specific property in base pairing of DNA in the double helix. Therefore, recognition events must have been central to early self-assembly of primitive genetic material, genomes, cells, genetic recombination and especially in enzyme-substrate-product recognition events. Molecular recognition events are examined with an emphasis on their central role in early prokaryotic evolution.

Notes: Abstract The transfer of genetic information by transformation, conjugation and transduction in bacteria occurs frequently in nature. These diverse gene transfer mechanisms in bacteria are the result of evolution and are not linked to reproduction as in eukaryotic organisms. In this review, gene transfer in bacteria will be considered from an evolutionary perspective.

Notes: Abstract About 80% of the evolutionary history of life on Earth is restricted to microorganisms which have had several billion years to speciate. The reasons for the origin (self-assembly) of life on Earth, bacterial cell division and why there are so many different bacteria and their global dispersal are discussed from an evolutionary perspective.

Notes: Abstract A 1.3 kb Brucella-specific DNA fragment produced through the use of arbitrarily primed polymerase chain reaction (AP-PCR) was tested for its specificity by DNA–DNA hybridization to Brucella and non-Brucella bacteria. The digoxigenin (DIG)-labelled 1.3 kb DNA fragment hybridized with Brucella abortus and Brucella melitensis but did not hybridize with other non-Brucella bacteria tested. The sensitivity of the reaction was determined; as little as 150 fg DNA or 30 Brucella cells could be detected. The specificity and sensitivity of the 1.3 kb DNA fragment combined with the simplicity and speed of the technique suggest the potential of this fragment as a DNA probe for the quick and reliable detection of Brucella organisms.

Notes: Abstract The entire Baltic Sea, as well as many of its different sub-regions, are subject to eutrophication due to high nutrient inputs. To plan expensive water management measures one needs a tool to quantify effects of different water management policy decisions. The tools implemented here are simulation models based on similar descriptions of biochemical interactions in the water and sediments but coupled to different hydrodynamical models. For the Baltic Proper a 1D physical model with high vertical resolution but horizontally integrated was used. Simulations for 20 years made with 50% load reduction each 5 year show that for this domain and at these scales the recovery would take decades. The most effective is reduction of phosphorus, while reduction of only nitrogen leads to a dramatic increase in cyanobacteria blooms. For the Gulf of Finland a high-resolution 3D hydrodynamic model was coupled to a more crude 3D-box biogeochemical model describing concrete conditions during August and November 1991. In the Eastern Gulf of Finland the effects of a 50% load reduction from the St. Petersburg region are pronounced even after two weeks. Here, nitrogen reduction would be more beneficial than that of phosphorus, both locally and at a larger scale. The conclusion from these simulations is that the difference in effects of nitrogen versus phosphorus reduction is dependent on scales and locations of management.

Notes: Abstract There is no single piece of legislation which comprehensively addresses the problem of eutrophication of freshwater lakes. An examination is made of the extent to which national and EU laws applicable in England and Wales may be used to reduce phosphorus inputs to eutrophicated lakes. This case study is then used to outline the shortcomings of existing legislation and the future challenges for lake eutrophication control. Applicable legislation may be divided into that relating to nature conservation, to water quality and to agricultural extensification. Nature conservation laws are applicable, in that lakes designated as Sites of Special Scientific Interest (SSSIs), are theoretically safeguarded from degradation. The main limitation of the SSSI system lies in the boundary definition process under which, as a rule, no other category of legally protected land may be designated. Thus, the use of surrounding buffer land to protect water quality at the catchment level is generally precluded. The introduction of consultation areas around SSSIs of international importance under the EU Directive on Habitats is unlikely to alleviate the problem, since the area involved remains minimal compared to the extent of the majority of catchments. Intensive agricultural practices are responsible for significant nutrient enrichment of rivers and lakes, so that legislation aimed at extensification is also relevant. Examples of agricultural extensification include the Environrnentally Sensitive Areas programme and various options available for Set-Aside land. However, the prime purpose of such initiatives is the alleviation of surplus and budgetary problems and, as such, they fall short of a fully integrated approach to the ecological management of farmland. Nutrient enrichment is, essentially, a water quality issue, but policy and legislation in this area are not yet sufficiently developed to address the problem comprehensively. The current regulatory process for water quality carries the potential to work comparatively well for point sources under the system of consents to discharge. This potential is limited, however, by the paucity of information available on ecologically acceptable concentrations of phosphorus in discharges. In addition, the consents system is not constructed to deal effectively with diffuse agricultural losses of phosphorus, since, unlike point sources, these tend to arise from the cumulative effect of many activities. The main legislative challenge for lake eutrophication control lies in the area of diffuse agricultural losses of phosphorus. In this respect, experience in the U.S.A. reveals that the use of comprehensive and catchment-wide ‘Best Management Practices’ is capable of producing significant water quality improvements, providing that some degree of mandatory compliance is incorporated.

Notes: Abstract The majority of Danish lakes are highly eutrophic due to high nutrient input from domestic sources and agricultural activities. Reduced nutrient retention, and more rapid removal, in catchments as a result of agricultural drainage of wetlands and lakes and channelisation or culverting of streams also play a role. Attempts have recently been made to reduce nutrient loading on lakes by intervening at the source level and by improving the retention capacity of catchment areas. The former measures include phosphorus stripping and nitrogen removal at sewage works, increased use of phosphate-free detergents, and regulations concerning animal fertiliser storage capacity, fertiliser application practices, fertilisation plans and green cover in winter. In order to improve nutrient retention capacity of catchments, wetlands and lakes have been re-established and channelised streams have been remeandered. In addition, cultivation-free buffer strips have been established alongside natural streams and there has been a switch to manual weed control. These measures have resulted in a 73% reduction of the mean total phosphorus concentration of point-source polluted streams since 1978; in contrast, there has been no significant change in the total nitrogen concentration. Despite the major reduction in stream phosphorus concentrations, lake water quality has often not improved. This may reflect a too high external or internal phosphorus loading or biological resistance. Various physico-chemical restoration measures have been used, including dredging and oxidation of the hypolimnion with nitrate and oxygen. Biological restoration measures have been employed in 17 Danish lakes. The methods include reducing the abundance of cyprinids, stocking with 0+ pike ( Esox lucius) to control 0+ cyprinids, and promoting macrophyte recolonization by protecting germinal submerged macrophyte beds against grazing waterfowl and transplanting out macrophyte shoots. In several lakes, marked and long-lasting improvements have been obtained. The findings to date indicate that fish manipulation has a long-term effect in shallow lakes, providing nutrient loading is reduced to a level so low as to ensure an equilibrium lake water phosphorus concentration of less than 0.05–0.1 mg phosphorus l−1. If nitrogen loading is very low, however, positive results may be obtained at higher phosphorus concentrations. Macrophyte refuges and transplantation seem to be the most successful as restoration measures in the same nutrient-phosphorus regime as fish manipulation.

Notes: Abstract Sustainable lake management for nutrient-enriched lakes must be underpinned by an understanding of both the functioning of the lake, and the origins of changes in nutrient loading from the catchment. To date, limnologists have tended to focus on studying the impact of nutrient enrichment on the lake biota, and the dynamics of nutrient cycling between the water column, biota and sediments within the lake. Relatively less attention has been paid to understanding the specific origins of nutrient loading from the catchment and nutrient transport pathways linking the lake to its catchment. As such, when devising catchment management strategies to reduce nutrient loading on enriched lakes, assumptions have been made regarding the relative significance of non-point versus point sources in the catchment. These are not always supported by research conducted on catchment nutrient dynamics in other fields of freshwater science. Studies on nutrient enrichment in lakes need to take account of the history of catchment use and management specific to each lake in order to devise targeted and sustainable management strategies to reduce nutrient loading to enriched lakes. Here a modelling approach which allows quantification of the relative contribution of nutrients from each specific point and non-point catchment source over the course of catchment history is presented. The approach has been applied to three contrasting catchments in the U.K. for the period 1931 to present. These are the catchment of Slapton Ley in south Devon, the River Esk in Cumbria and the Deben Estuary in Suffolk. Each catchment showed marked variations in the nature and intensity of land use and management. The model output quantifies the relative importance of point source versus non-point livestock and land use sources in each of the catchments, and demonstrates the necessity for an understanding of site-specific catchment history in devising suitable management strategies for the reduction of nutrient loading on enriched lakes.

Notes: Abstract In Small Bay, Saldanha, the water becomes highly stratified in summer. The cold bottom layer (of upwelling origin) is rich in nitrogen, some of which enters the surface layer by advection. However, the surface water often becomes warm and oligotrophic leading to poor growth or death of Gracilaria gracilis grown in experimental suspended systems. At the same time, large quantities of nitrogen-rich fish waste are released at a particular site in the bay. We tested the hypothesis that Gracilaria grown close to the site of waste release (1.5 km away and in the waste plume) would grow faster than at the control site 3.5 km away. In October and November (early summer) 1996, all the Gracilaria at the control site died, while growth at the fish waste site was good (between 8 and 10% day−2). In November–December control plants grew slightly faster than those from the waste site, in February the reverse occurred, and subsequently (March–June) growth was s imilar at both sites as winter winds caused mixing of the water column. These results, and analyses of the C/N ratios of the Gracilaria tissues provide some support for our hypothesis. Also, analyses of the stable N isotope ratios in the Gracilaria tissues indicate that there is considerable uptake of the fish-waste N even at the control site. We conclude that while proximity to the waste site may sometimes benefit the Gracilaria, the fish waste would in fact provide a significant source of N for seaweed cultivated throughout the northern area of Small Bay, particularly when the water is highly stratified in summer.

Notes: Abstract The debates about the relationship among clitellate taxa at research conferences on aquatic oligochaetes have provided two alternative hypotheses. While both involve cladistic analyses, the differences focus on questions of homology. A single unique synapomorphy supports a taxon consisting of Branchiobdellida plus Lumbriculidae. Muscle ultrastructure provides a potential autapomophy for Lumbriculidae within the clade, while Branchiobdellida has many autapomophies. Some proposed synapomorphies for a Branchiobdellida plus Hirudinea grouping (jaws, oral sucker) are not based on homologous structures. Others (loss of chaetae, median male pore) are not unique, or are based on potentially convergent characters. Initial molecular analyses support a Branchiobdellida - Hirudinea grouping. A preliminary manually drawn cladogram based on re-evaluated characters supports Lumbriculidae, Branchiobdellida, Acanthobdella and Euhirudinea as a monophyletic taxon. Observations on sperm ultrastructure support this hypothesis. If substantiated, a very considerable change in nomenclature will result. However, before any nomenclatural changes are proposed, a resolution of the apparently paraphyletic Oligochaeta is necessary.

Notes: Abstract The identification of populations of Bruguiera sexangula, Bruguiera gymnorhiza and their putative hybrids in the field is difficult using only morphological and phenological characters. Using a PCR based technique, RAPD (Random Amplified Polymorphic DNA), the genetic variation of Bruguiera populations was studied from contrasting climatic and geographic regions along the southwest coastal region of Sri Lanka. Out of 45 primers screened, 20 primers allowed us to observe polymorphism, not only between species (interspecific) but also within the species (intraspecific). Analysis of RAPD data appears to be helpful in determining the genetic relationship among populations of B. gymnorhiza and B. sexangula. RAPD markers revealed that the two species are well separated without any hybrid position between the two taxa though they occur in mixed stands. Although sampling sizes of populations of this study were small, genetic variation among B. gymnorhiza and B. sexangula populations could be observed. For B. sexangula, it was possible to differentiate each of the three populations, even when using a small number of primers.

Notes: Abstract Enzyme polymorphisms have been widely used in aquatic plants since the 1980s. Studies on DNA polymorphisms are less numerous and a case-study using both methods on Scirpus is worked out. Along the unique freshwater tidal zone of the River Schelde (Belgium), clumps of Scirpus species are mostly scattered in small and fragmented locations on the dikes and mud flats. Most of these taxa are native S. triqueter, S. tabernaemontani or intermediate morphological forms. However, several cultivated strains of S. tabernaemontani have been introduced in recent years. Such ‘exotic’ strains have been planted to stabilize the muddy riverbanks and became well established and may perform better than the native hybrid complex. In order to determine the existing genetic diversity among these species and the possibility for genetic pollution, stems of 30 clumps from a series of locations along the tidal river were investigated for seven enzymes (SDH, PGM, EST, MNR, GOT, 6PGD and ME) and for markers at DNA level using random amplified polymorphic DNA's (RAPD) of 22 decanucleotides. Data analysis of the allozymes and of the amplified DNA fragments enabled us to classify unambiguously the different Scirpus taxa. Direct evidence of hybridization between S. triqueter and S. tabernaemontani could not be obtained, but the putative hybrids are genetically intermediate or close to S. triqueterwhen considering the DNA polymorphism. The introduced clones of S. tabernaemontani consisted of at least three groups of genotypes of which one was very related to the native ones. The escaped clumps could be assigned to a third introduced but less-related strain.

Notes: Abstract Lack of knowledge of early and juvenile development often makes it difficult to decide when a fish becomes a juvenile or, for that matter, a definitive phenotype. According to the established life-history model, a fish develops naturally in a saltatory manner, its entire life consisting of a sequence of stabilized self-organizing steps, separated by distinct less stabilized thresholds. Changes are usually introduced during thresholds. In principle, there are two ways to reach the juvenile period: by indirect or by direct development. Indirectly developing fishes have a distinct larva period that ends in a cataclysmic or mild remodeling process, called metamorphosis, from which the fishes emerge as juveniles. During metamorphosis, most temporary organs and structures of the embryos and larvae are replaced by definitive organs and structures that are also possessed by the adults. In contrast, directly developing fishes have no larvae. Their embryos develop directly into juveniles and do not need major remodeling. Consequently, the beginning of their juvenile period is morphologically and functionally less distinct than in indirect development. The life-history model helps to find criteria that identify the natural boundaries between the different periods in the life of a fish, among them, the beginning of the juvenile period. Looking at it from a different angle, when ontogeny progresses from small eggs with little yolk, larvae are required as the necessary providers of additional nutrients (‘feeding entities’ similar to amphibian tadpoles or butterfly caterpillars) in order to accumulate materials for the metamorphosis into the definitive phenotypes. Directly developing fishes start with large demersal eggs provided with an adequate volume of high density yolk and so require no or little external nutrients to develop into the definitive phenotype. These large eggs are released and develop in concentrated clutches. It therefore becomes possible and highly effective to guard them in nests or bear them in external pouches, gill chambers or the buccal cavity. Viviparity is the next natural step. Now the maternal investment into large yolks can be supplemented or replaced by direct food supply to the developing embryos like, for example, the secretion of uterine histotrophe or nutrient transfer via placental analogues. When the young of guarders and bearers start exogenous feeding, they are much larger or better developed than larvae of nonguarders and the larva period in the former is reduced to a vestige or eliminated entirely. In the latter case, the juvenile period begins with the first exogenous feeding. Such precocial fishes are more specialized and able to survive better in competitive environments. In contrast, altricial forms retain or revert to a life-history style with indirect development and high fecundity when dispersal is advantageous or essential. Fishes become juveniles when the definitive phenotype is formed in most structures, either indirectly from a larva via metamorphosis or directly from the embryo.

Notes: Abstract Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/l) and lowest in bare plots in the shrubland (0.55 mg/l). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands – consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.

Notes: Abstract During a two-year field study, an annual nutrient budget and cycles were developed for a small agricultural watershed. The study emphasized the integrated unit of the watershed in understanding the biogeochemistry. It was found that the total nutrient input was 39.1× 104 kg nitrogen and 3.91×104 kg phosphorus in the year 1995, of which the greatest input of nutrients to the watershed was chemical fertilizer application, reaching 34.7×104 kg (676 kg/ha) nitrogen and 3.88×104 kg (76 kg/ha) phosphorus. The total nutrient output from the watershed was 13.55×104 kg nitrogen and 0.40×104 kg phosphorus, while the largest output of nitrogen was denitrification, accounting for 44.1% of N output; the largest output of phosphorus was sale of crops, accounting for 99.4% of P output. The results show that the nutrient input is larger than output, demonstrating that there is nutrient surplus within the watershed, a surplus which may become a potential source of nonpoint pollution to area waters. The research showed that both denitrification and volatilization of nitrogen are key ways of nitrogen loss from the watershed. This suggests that careful management of fertilizer application will be important for the sustainable development of agriculture. The research demonstrated that a multipond system within the watershed had high retention rate for both water and nutrients, benefiting the water, nutrient and sediment recycling in the terrestrial ecosystem and helping to reduce agricultural nonpoint pollution at its source. Therefore, this unique watershed system should be recommended due to its great potential relevance for sustainable agricultural development.

Notes: Abstract Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/1) and lowest in bare plots in the shrubland (0.55 mg/1). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands — consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.

Notes: Abstract Nitrogen additions as NH4NO3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m−2 yr−1 were made toSphagnum magellanicurn cores at two-week intervalsin situ at four sites across Europe, i.e. Lakkasuo (Finland). Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artificially maintained at 7, 17 and 37 cm below the moss surface. In the field, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N∶P ratio 68) and greatest in Moidach More (N∶P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in field sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH4 + in the underlying peat at 30 cm depth, both in response to NH4NO3 addition and in the unamended cores confirmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the profiles at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO3 − were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition bySphagnum mosses.

Notes: Abstract Two-year old nectarine trees (Prunus persica, Batsch, var. nectarina, cv. Starkredgold on GF305 rootstock) planted in pots each received five applications of 1.0 g 15N labelled urea either from mid May to mid July (early uptake) or from mid August to the beginning of October (late uptake). All trees were supplied with a corresponding amount of unlabelled urea when they did not receive the labelled N. In autumn, all abscised leaves were collected and during winter randomly selected trees were harvested and divided into main organs. The remaining trees were transplanted into similar pots filled with sand; they received no N fertiliser and were harvested in May to evaluate the remobilisation of N. Total N and 15N abundance were determined in each organ. Nectarine trees took up similar amounts of N in the 'early' and in the 'late' period; however, more labelled nitrogen was recovered in the perennial organs during the winter when trees received the labelled N in the 'late' than in the 'early' period. Some 73–80% of the N present in the dormant trees was stored in the roots, which contained almost twice the amount of labelled N taken up 'late' than that absorbed 'early'. Nitrogen for spring growth was remobilised predominantly from the roots and accounted for some 43–49% of the labelled N recovered in the tree during winter. Results suggest that the nitrogen taken up 'late' in the season is preferentially stored in roots and used by peach trees to sustain new growth the following spring.

Notes: Abstract Nematodes are increasingly being used in environmental studies. One of the potential parameters to measure the impact of disturbances and to monitor changes in structure and functioning of the below-ground ecosystem is the nematode Maturity Index; an index based on the proportion of colonizers (r-strategists s.l.) and persisters (K-strategists s.l.) in samples. In this paper the original allocation of nematode taxa on the colonizer-persister scale, and the tolerance and sensitivity of colonizers and persisters are discussed from an evolutionary viewpoint. The phenomenon that neither relative egg size nor body length is an unequivocal character to scale nematodes suggests that the main selection for life history traits occurred independently in the major evolutionary branches.

Notes: Abstract Inorganic nitrogen and soluble reactive phosphate (o-P) concentrations were measured in the water of a marsh and in its interstitial water at two sites, and in the river water of a floodplain marsh of the Lower Paraná River. These values were compared with the N and P concentration in sediments and macrophyte biomass in order to assess nutrient availability, fate and storage capacity. High variability was found in the interstitital water using a 1 cm resolution device. Nitrate was never detected in the pore water. Depth averaged NH4 + concentrations in the upper 30 cm layer often ranged from N = 1.5 to 1.8 mg l-1, but showed a pronounced minimum (0.5–0.7 mg l-1), close to (March 95), or relatively soon after (May 94) the end of the macrophyte growing season. Soluble phosphate showed a large variation between P = 0.1–1.1 mg l-1 without any discernible seasonal pattern. NH4 + depletion in the pore water concentration and low N/P ratios (3.7 by weight) within the macrophyte biomass at the end of the growing period suggest that available N limits plant growth. NH4 + and o-P concentrations were 35 and 7 times higher, respectively, in the pore water than in the overlying marsh, suggesting a permanent flux of nutrients from the sediments. o-P accumulate in the marsh leading to higher concentrations than in the incoming river. NH4 + did not accumulate in the marsh, and no significant differences were observed between the river and the marsh water, while the NO3 - contributed by the river water was depleted within the marsh, caused probably by coupled nitrification-denitrification at the sediment–water interface. Although an order of magnitude smaller, the pore water pool can supply enough nutrients to build up the macrophyte biomass pool, but only if a fast turnover is attained. The Paraná floodplain marsh retains a large amount of nutrients being stored mainly in the sediment compartment.

Notes: Abstract Seasonal changes of total particulate material (TPM), particulate organic carbon (POC), nitrogen (PON) and phosphorus (PTP) concentrations in the water column, in sediment traps and on the sediment surface were studied in the SW coast of Finland, Baltic Sea, from March to November 1992. Sampling was carried out along a coastal gradient from the fjord-like, semi-enclosed Pojo Bay to the outer archipelago and open sea area. In Pojo Bay, TPM sedimentation rates were high and relatively constant, and had low organic carbon contents throughout the seasonal cycle. Resuspension was estimated to contribute 〉 90% of total sedimentation of POC and PON. Clear seasonality in sedimentation with high settling rates of primary organic material in spring, low sedimentation rates during summer and a considerable increase of resuspension during autumn was found in the outer archipelago and open sea. The C:N:P ratios of suspended, settled and sediment surface material indicated greater sedimentary loss of N (as compared to P and C) and closer coupling between pelagial and benthos in the archipelago and open sea area than in Pojo Bay. The sedimentation of P was 20–50% more effective (as compared to N and C) in Pojo Bay than elsewhere. These results indicate that the shift of planktonic nutrient limitation (from P to N limitation) is enhanced due to the more efficient sedimentation of the main limiting element along the estuarine gradient. The primary sedimentation of organic carbon (approximating export flux from the pelagic system) during the whole study period was estimated to be 30–48% of the total net primary production. This indicates that despite the differences in the salinity, nutrient dynamics and planktonic community structure along the coastal gradient, a relatively constant fraction of the annual primary production is exported from the pelagic system by sedimentation.

Notes: Abstract Partial 18S rDNA sequences, including a 102 base pair insertion, were used to infer a phylogeny among 48 samples across all sections in Halimeda Lamouroux, 1812. The phylogeny reveals a separation of the monophyletic section Rhipsalis into a western Atlantic and a western Pacific clade. Consequently, morphologically similar species within this section such as H. monile (Ellis & Solander) Lamouroux (western Atlantic), and H. cylindracea Decaisne (western Pacific), are not sister taxa. Vicariant events that separated the tropical regions of the Atlantic and Indo-Pacific Oceans can explain the observed biogeographical pattern in section Rhipsalis.

Notes: Abstract Agametic reproduction by fission has evolved numerous times in the Annelida. In this group, as well as others, the developmental processes of fission appear to be based on those of regeneration. Thus far, all fissiparous annelids whose regenerative abilities have been investigated fully are capable of regenerating both anteriorly and posteriorly. However, in this paper, I describe a unique exception to this association between fission and regenerative abilities. Regeneration experiments demonstrate that the fissiparous annelid Paranais litoralis (Oligochaeta: Naididae) has lost the capacity for full anterior regeneration. The four anterior segments of P. litoralis are produced routinely during each round of fission, yet this species is incapable of producing these same segments by anterior regeneration. I propose that fissiparous reproduction, possibly coupled with a low susceptibility to amputation in nature, may have relaxed selection for anterior regeneration in P. litoralis. The decoupling of fission and regenerative abilities suggests that some steps in the developmental trajectories that lead to fission and regeneration may have diverged in this species.

Notes: Abstract Monitoring data obtained from 231 freshwater lakes and ponds in the Netherlands, covering the period 1980–1996, were used to analyse the relationships between (a) transparency and chlorophyll-a, and the effect of system characteristics on this relationship, (b) chlorophyll-aand nutrient concentrations, and the effect of biological variables and (c) nutrient concentrations and nutrient loading. (a) Chlorophyll-aimposes a maximum on water transparency, but deviations from this maximum can be large. Reducing chlorophyll-a, therefore, does not guarantee a sufficient improvement of transparency. Soil type and the average depth of a lake were shown to influence the relationship between chlorophyll-aand transparency. (b) The maximum ratios of both chlorophyll-a: total-P and chlorophyll-a: total-N were higher in systems dominated by filamentous cyanobacteria than in systems dominated by other algae, indicating the efficiency of the former group with respect to nutrients. In systems with an areal coverage with submersed macrophytes above 5%, concentrations of chlorophyll-aand nutrients were lower than in systems with lower coverages. The ratios between chlorophyll-aand nutrients were lower at coverages larger than 10%. This indicates both bottom-up and top-down control of algae by macrophytes. Grazing pressure by zooplankton was also found to lower the chlorophyll-a: nutrient ratios. (c) System specific linear relationships were found between the average concentrations of total-P and total-N in the incoming water and the summer mean concentration in the lake. This allows the assessment of admissible loads for individual lakes, with narrower confidence limits compared to traditional relationships based on combined data from many lakes. From the analysis, it is concluded that the chain of relationships from nutrient loading to transparency is complex, and depends on biological variables as well as system characteristics.

Notes: Abstract Data for comparison are from 17 dimictic and four polymictic lakes interconnected to form a system of the Great Masurian Lakes. Both summer epilimnetic total phosphorus and chlorophyll were higher in dimictic than in polymictic lakes. Chlorophyll was probably not limited either by phosphorus or by nitrogen in shallow lakes. Utilization of phosphorus in terms of chlorophyll:particulate phosphorus and chlorophyll:particulate nitrogen ratios was similar in the two groups of lakes. Significant differences were found, however, in the chlorophyll:seston ratio, higher in dimictic lakes. These observations together suggest that seston in shallow lakes contains a significant, though unpredictable contribution of detritus/mineral particles much poorer in phosphorus than those in dimictic lakes. Secchi disc depth was better explained in shallow lakes by seston variability than by chlorophyll. Thus, algal production in shallow masurian lakes seems to be limited by light conditions resulting from resuspension of non-living particles while the production in deep lakes is nutrient (both nitrogen and phosphorus) limited.

Notes: Abstract The relation between (inter)national programs aiming at nutrient load reduction and changes in eutrophication has been studied for 231 Dutch lakes over the period 1980–1996. Trends in total-phosphorus (P) and total-nitrogen (N) were negative, as determined by analysis of both individual lakes and the complete data set. The relative trends in the nutrient concentrations as well as in the N/P ratio correspond with the significantly reduced P emission and the limited reduction of N emission in The Netherlands since the beginning of the 1980s. Negative trends in chlorophyll-aand positive trends in Secchi-disc transparency may be partly explained by reduced nutrient concentrations. Perspectives for the nearby future are discussed. Lake characteristics had only a minor impact on the trends. The improvement of the water quality was found for all subsets of average depth, surface area, hydraulic retention time and soil type. Furthermore, the effect of restoration measures and meteorological conditions on the trends were studied. Biomanipulation resulted in an additional improvement of several water quality variables compared to lakes that were only subject to (inter)national programs on nutrient load reduction. Specific measures resulting in additional P load reduction resulted only in lowered P concentrations. Severe winters resulted in lower chlorophyll-aconcentrations in the following summer and dry conditions in spring were favourable for all eutrophication variables in the following summer.

Notes: Abstract Nutrient loading by riverine input into estuarine systems has increased by 6–50 times for the N load from pristine conditions to present, whereas a 18–180 times increase has been observed in the P load. Reductions in the ratio of N to P delivery has also occurred with time. In a review of nutrient limitation in estuarine systems, it is shown that many estuarine systems display P limitation in the spring, switching to N limitation in the summer with some estuaries displaying dissolved silicate limitation of the spring diatom bloom. Historical and recent changes in nutrient loading and their effect on nutrient limitation have intensified the debate on the control of nutrient delivery to estuaries from both agricultural and point sources, and as to what nutrient (N or P) should be managed for in estuarine systems. It is hypothesized that potential reductions in P may help oxygen depletion especially in deep estuaries and reduce fast growing macrophytes such as Ulva sp., although P reductions probably will have little effect on summer chlorophyll concentrations, an important recreational management goal. Reductions in N loading should reduce summer chlorophyll concentrations and improve the conditions for submerged aquatic vegetation and thus improve ecosystem functioning. Finally, if only P reductions are pursued, that is if we are able to reduce P such that it is limiting year around in estuarine systems, it is likely that the export of N from estuarine systems would increase to the bordering N-limited marine systems, thus only exporting the problem of enhanced production with eutrophication.

Notes: Abstract The distribution and accumulation of organic matter, nitrogen (N) and phosphorus (P) in mangrove soils at four sites along the Shark River estuary of south Florida were investigated with empirical measures and a process-based model. The mangrove nutrient model (NUMAN) was developed from the SEMIDEC marsh organic matter model and parameterized with data from mangrove wetlands. The soil characteristics in the four mangrove sites varied greatly in both concentrations and profiles of soil carbon, N and P. Organic matter decreased from 82% in the upstream locations to 30% in the marine sites. Comparisons of simulated and observed results demonstrated that landscape gradients of soil characteristics along the estuary can be adequately modeled by accounting for plant production, litter decomposition and export, and allochthonous input of mineral sediments. Model sensitivity analyses suggest that root production has a more significant effect on soil composition than litter fall. Model simulations showed that the greatest change in organic matter, N, and P occurred from the soil surface to 5 cm depth. The rapid decomposition of labile organic matter was responsible for this decrease in organic matter. Simulated N mineralization rates decreased quickly with depth, which corresponded with the decrease of labile organic matter. The increase in organic matter content and decrease in soil bulk density from mangrove sites at downstream locations compared to those at upstream locations was controlled mainly by variation in allochthonous inputs of mineral matter at the mouth of the estuary, along with gradients in mangrove root production. Research on allochthonouns sediment input and in situ root production of mangroves is limited compared to their significance to understanding nutrient biogeochemistry of these wetlands. More accurate simulations of temporal patterns of nutrient characteristics with depth will depend on including the effects of disturbance such as hurricanes on sediment redistribution and biomass production.

Notes: Abstract It is clear that the spiralian developmental program represents a highly flexible platform for the generation of diverse larval and adult body plans. The widespread occurrence of this pattern of early development attests to its tremendous evolutionary success. Despite the large degree of conservation in the spiral cleavage pattern and other basic aspects of early development, changes in cell fate maps and in the mechanisms of blastomere specification have arisen. While we have learned a great deal about this mode of development, a number of important questions remain to be answered. To what extent do these conditions apply to the lesser studied spiralian phyla? What constraints have led to the preservation of the early spiral cleavage program? How has this developmental program been adapted for the construction of the various spiralian body plans (e.g. the segmental body plans of annelids or to the potential secondary loss of segmentation)? Are most changes associated with the elaboration of these different larval and adult body plans restricted to the late period of development? What molecular/genetic processes underlie this developmental program? Clearly, the spiralian phyla represent an important group of organisms for further studies on development and evolution.