ALBERT

Notes: Abstract The porin from lithoautotrophically grown Rhodobacter capsulatus 37b4 cells migrated identically to porin from organoheterotrophic cells on SDS-PAGE. Moreover, it behaved comparably in isoelectric focusing, and it was also EDTA-sensitive. Furthermore, the porins of the two growth conditions were essentially identical in amino acid composition and N-terminal amino acid sequence. A final proof for structural identity could be obtained by crystallization and structural analysis showing identity in all non-hydrogen atoms.

Notes: Abstract— Plasma profiles of reproductive and thyroid hormones were studied in captive striped bass Morone saxatilis during an 11-wk period encompassing the spawning season, and the effect of a sustained-release gonadotropin-releasing hormone agonist (GnRHa)-delivery system (GnRHa-implant) on milt production was evaluated. The highest percentage of spermiating fish was observed between mid-April and mid-May, and mean total expressible milt ranged from 3.5 to 6.0 mL/kg. Plasma gonadotropin II (GtH II) increased significantly, though inconsistently, during the spermiation period, whereas testosterone and 11-ketotestosterone levels declined continually. Plasma 17,20β-dihydroxy-4-pregnen-3-one and 17,20β,21-dihydroxy-4-pregnen-3-one remained low and unchanged during the peak of the spermiation period, while thyroid hormones were high and fluctuated without exhibiting a trend consistent with spermiation. The observed endocrine profiles suggest that captivity can diminish plasma GtH II and triiodothyronine levels in striped bass. Transfer of spermiating males from large holding tanks to small spawning tanks reduced total expressible milt after 14 d, but treatment with a GnRHa-implant restored milt volume, presumably due to the prolonged elevation of plasma GnRHa and GtH II induced by the GnRHa-implant. Also, treatment with the GnRHa-implant induced a two- to four-fold elevation of expressible milt for at least 20 d compared to control fish, while resulting in only a 5 to 15% decrease in sperm density. It appears that captivity and hatchery operations can diminish milt production in striped bass, and that GnRHa-delivery systems, via sustained elevation of plasma GtH II, can induce long-term enhancement in milt volume without affecting sperm density greatly.

Notes: Abstract: The in situ temperature of the profundal sediment of Lake Constance is constant at 4°C. Methanogenic bacteria could not be detected at 6°C by the most probable number (MPN) technique using acetate and 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu1" location="equation/FEM_1_mu1.gif"/〉 as methanogenic substrates. Instead, homoacetogenic bacteria were detected on 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu2" location="equation/FEM_1_mu2.gif"/〉. At a higher temperature of 20°C, however, methanogenic bacteria were found in numbers of about 105 cells ml−1 with 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu3" location="equation/FEM_1_mu3.gif"/〉 and about 5 × 104 cells ml−1 with acetate. However, CH4 production was observed at both 4°C and 20°C. Production of CH4 was inhibited by chloroform and fluoroacetate and the accumulation of intermediary metabolites was measured. At the in situ temperature of 4°C, only acetate accumulated in presence of chloroform. Hydrogen partial pressures were at the same low value of about 0.5 Pa as in the uninhibited control. The amount of accumulated acetate was similar to that of CH4 in the uninhibited controls. Similar results were obtained with fluoroacetate which inhibits methanogenesis from acetate. Addition of H14CO3− did not result in the formation of 14CH4 after 28 days of incubation. However, [2-14C]acetate was immediately converted to 14CH4. The results indicate that methanogenesis at 4°C was exclusively due to acetate cleavage. At 20°C, by contrast, accumulation of H2 was observed in addition to that of acetate, propionate, valerate, caproate, methanol and isopropanol, when CH4 production was inhibited by chloroform. Thermodynamic calculations indicated that the accumulation of the fatty acids was a consequence of feedback inhibition by the accumulated H2. Balance calculations indicated that at 20° about 22% of the CH4 originated from reduction of CO2. Experiments with H14CO3− indicated that about 33% of the CH4 originated from 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu4" location="equation/FEM_1_mu4.gif"/〉 at 20°C. Thermodynamic calculations showed that homoacetogenesis from 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu5" location="equation/FEM_1_mu5.gif"/〉 was endergonic, whereas methanogenesis from acetate or 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu6" location="equation/FEM_1_mu6.gif"/〉 was exergonic at both 4°C and 20°C. Low sediment temperatures obviously limited methanogenesis from 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu7" location="equation/FEM_1_mu7.gif"/〉 for reasons other than thermodynamics. Simultaneously, degradation processes seemed to be dominated by homoacetogenic degradation of organic matter followed by acetoclastic methanogenesis. However, increase of temperature resulted in a dramatic shift of the degradation pathway enhancing the role of H2 as an intermediate.

Notes: The European com borer (ECB) Ostrinia nubilalis H. is a major pest in World maize Zea mays L. production. Objectives of this study were to (1) investigate the genotypic variance and covariance in testcrosses of European flint and dent inbreds for ECB resistance and agronomic traits, and (2) estimate the correlation between line per se and testcross performance for ECB resistance traits. A total of 16 flint and 24 dent inbreds and their testcrosses with two testers from the opposite germplasm pool were evaluated in four and three German environments, respectively. Using artificial infestation with ECB larvae, resistance was assessed by damage rating of stalks, tunnel length in dissected stalks, and relative yield of infested plots compared with protected plots. Yield losses due to ECB damage in testcross hybrids amounted to 40%. Significant genotypic variances between flint and dent lines and high heritabilities were found for damage rating of stalks for both line per se and testcross performance. Heritabilities were low or intermediate for tunnel length and relative grain yield. Correlations between line per se and testcross performance were tight for the damage rating of stalks and moderate for tunnel length and relative yield in both flint and dent germplasm. For damage rating of stalks, per se performance of lines tested in a few environments can be used to predict their testcross performance. In contrast, assessment of testcross performance for tunnel length and relative yield requires evaluating testcrosses with several testers in multi-environment trials.

Notes: The univoltine European corn borer (ECB) has become a major limiting factor for maize (Zea mays L.) production in central Europe. The objective of this study was to survey the genetic variation for ECB resistance in European elite maize germplasm. Eighteen flint and 23 dent inbreds were screened under artificial ECB infestation at two locations in 1993 and 1994. Resistance was assessed by damage rating of broken plants, measurement of tunnel length in dissected stalks, and yield reduction in infested plots relative to insecticide-protected control plots. Flint lines showed significantly greater means for damage rating than dent lines with grain yield reduction of 35% and 24%, respectively. Significant genotypic variances among lines and high heritabilities were found for agronomic traits and damage rating. Heritabilities were intermediate for tunnel length and relative grain yield. Significant associations of days to silking, ear dry matter content, and dry matter yield of the whole plant with damage rating and tunnel length suggested a better resistance in late-maturing, high-yielding inbreds. Genotypic correlations of relative grain yield with tunnel length and damage rating ranged between −0.46 and −0.72. Partial correlations, eliminating the effect of flowering time, confirmed these associations. Damage rating of stalks is the most suitable trait for evaluation of ECB damage owing to its high heritability and easy recording. Tunnel length below the primary ear is a useful trait for assessing antibiosis because it is not correlated with days to silking. Inbreds with extreme resistance and susceptibility were identified which can be used as parents for establishing breeding and QTL mapping populations.

Notes: Sugarcane mosaic virus (SCMV) and maize dwarf mosaic virus (MDMV) are the most important viruses of maize in Europe. In field and greenhouse experiments, 122 early-maturing European maize inbreds (45 flint and 77 dent lines) were evaluated for their reaction to artificial inoculation by SCMV and MDMV. Three dent inbreds (D21, D32, FAP1360 A) with complete resistance and four dent inbreds (D06, D09, R2306, FAP1396A) with partial resistance against both potyviruses under both greenhouse and field conditions were identified. All other inbreds were highly susceptible to both SCMV and MDMV. Selection for virus resistance in maize breeding could be performed with only one virus at a time because all inbreds resistant to SCMV were also resistant to MDMV. Rank correlations between percentages of infected plants in greenhouse and field trials ranged from 0.51 to 0.72 for both SCMV and MDMV, suggesting that prescreening of breeding materials for virus resistance can be performed in the greenhouse but final evaluation in multilocation trials in the field is recommended.

Notes: In many plants, translocation of sucrose from mesnsophyll to phloem for long-distance transport is carrier-mediated. The sucrose H+-symporter gene SUT1 from potato is expressed at high levels in the phloem of mature, exporting leaves and at lower levels in other organs. Inhibition of SUT1 by expression of an antisense gene in companion cells under control of the rolC promoter leads to accumulation of high amounts of soluble and insoluble carbohydrates in leaves and inhibition of photosynthesis. The distribution of in situ localized starch does not correspond with areas of reduced photosynthesis as shown by fluorescence imaging. Dissection of antisense effects on sink and source organs by reciprocal grafts shows that inhibition of transporter gene expression in leaves is sufficient to produce chlorosis in leaves and reduced tuber yield. In contrast to the arrest of plasmodesmal development found in plants that express yeast invertase in the apoplast, in mature leaves of sucrose transporter antisense plants plasmodesmata are branched and have median cavities. These data strongly support an apoplastic mode of phloem loading in potato, in which the sucrose transporter located at the plasma membrane of the sieve element/companion cell complex represents the primary route for sugar uptake into the long-distance translocation pathway.

Notes: The small polypeptide ubiquitin participates in a variety of fundamental cellular events, such as cell differentiation, stress response, determination of steady state levels of regulatory proteins, cell cycle control, regulation of transcription, and programmed cell death. Although the complex mechanisms of these processes are not fully understood, ubiquitinylation of regulatory proteins involved in those events is obviously essential. Target proteins can be covalently coupled with one or a few ubiquitin molecules, which is supposed to present a (reversible) post-translational modification. Polyubiquitinylation, however, marks proteins selectively for degradation by the 26S proteasome. The ubiquitin system has been studied mostly with animal systems or yeast, but all basic reactions of ubiquitin appear in plants as well.The scope of this review is to summarize several implications of recent studies directed towards the plant ubiquitin system.

Notes: Sedimentological evidence indicates metre-scale, cyclic changes in global sea-level during Mesozoic greenhouse climates; the cyclicity is thought to be due to Milankovitch forcing. The absence of continental ice-caps requires other mechanisms than glacier build-up to explain these variations. We propose that thermal expansion of the entire oceanic water column may partly explain the observed sea-level variations on Milankovitch timescales. Using existing climate model results, we show that an increase in deep water temperature of ∼ 2°C and a corresponding sea-level rise of 1.7 m by thermal expansion can be induced by Milankovitch forcing via increased formation of warm deep waters in low latitudes.