Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat‐forming biota on a tropical coral reef

Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large‐scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large‐scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy‐forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO‐influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids (r = .9), siganids (r = .9), and mullids (r = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña‐related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat‐forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.     

Vocal Coordination of Group Movement by Green Woodhoopoes (Phoeniculus purpureus)

Communication signals are used by many species to maintain group cohesion when moving over larger areas. Groups of green woodhoopoes (Phoeniculus purpureus) generally move around their territory as a close‐knit unit. Dominant individuals were more likely than subordinates to initiate movement to a new foraging site, but there was no intersexual difference. Dominants were also more likely than subordinates to be followed immediately. Vocalizations were shown to play an important role in mobilization: in the thick forests inhabited by woodhoopoes, visual cues to coordinate movement are likely to be less successful. When responding to the rallying call of a neighboring group, dominants and subordinates were equally likely to lead, as were males and females. As other group members followed immediately on most of these occasions, vocalizations were less important in this context than when moving to a new foraging site.     

Effect of anti-mosquito antibodies on the infectivity of the rodent malaria parasite Plasmodium berghei to Anopheles farauti

The effect of mouse anti-mosquito antibodies, present in the bloodmeal, on the infectivity of Plasmodium berghei Vincke to Anopheles farauti Laveran was investigated. Significantly fewer oocysts developed in mosquitoes feeding on mice immunized with sugar-fed mosquito midgut antigens than in mosquitoes feeding on control mice. Mosquitoes feeding on mice immunized with the midgut antigens derived from sugar-fed mosquitoes also showed reduced mortality and had lower infection rates than those fed on unimmunized mice. Blood-fed midgut antigen was less effective in producing these effects than sugar-fed midgut antigen.     

Molecular biology of wound-inducible proteinase inhibitors in plants

Abstract. The techniques of molecular biology are being employed to investigate at the gene level the systemically mediated, wound-induced accumulation of two defensive proteinase inhibitor proteins in plant leaves. These techniques have added a new dimension to biochemical and physiological studies already underway to understand the mechanism of induction by wounding. The acquisition of cDNAs from the RNAs coding for the two inhibitors facilitated studies of mRNA synthesis in leaves in response to wounding, and provided probes to obtain wound-inducible proteinase inhibitor genes from tomato ( Lycopersicon esculentum ) and potato (Solarium tuberosum) genomes. Successful transformations of tobacco plants with fused genes, containing the 5' and 3' regions of the inhibitor genes with the open reading frame of the chloramphenicol acelyltransferase ( cat ) gene, have provided a wound-inducible chloramphenicol acetyltransferase (CATase) activity with which to seek cis- and transacting elements that regulate wound-inducibility to help to understand the interaction of cytoplasmic and nuclear components of the intracellular communication systems that activate the proteinase inhibitor genes in response to wounding by insect pests.     

Effect of radiomodifying agents on the ratios of X-ray-induced lesions in cellular DNA: use in lethal lesion determination

The effect of three radiomodifying agents, cysteamine, hyperthermia, and hypoxia, on the induction of the major classes of X-ray-induced DNA lesions, was studied using mouse L cells and Chinese hamster V79 cells. The use of filter elution techniques allowed most of these studies to be conducted at X-ray doses within the survival-curve range. Cysteamine was found to protect against DNA single-strand breakage (ssb), DNA base damage, and DNA-protein crosslinkage. Hyperthermia had no effect on the level of DNA ssb or DNA base damage, but in L cells (but not in V79 cells) it increased the level of DNA-protein crosslinkage relative to DNA ssb. Hypoxia protected against DNA ssb, had no significant effect on the level of DNA base damage, and enhanced the level of DNA-protein crosslinkage relative to DNA ssb. These results support the previous suggestion that the X-ray-induced lethal lesion is DNA double-strand breakage. Implications of these findings for the mechanisms of formation of X-ray-induced DNA lesions are also discussed.     

The cellulase complex of Neurospora crassa: activity, stability and release

The temperature and pH optima, and the temperature and pH stability, of crude and purified enzymes of the cellulase complex of the cellulolytic ascomycete fungus Neurospora crassa were investigated. The effects of some non-ionic surfactants and fatty acids on the production/release of enzymes of cellulase complex were also examined. For the different enzymes of the complex, activity maxima occurred between pH 4.0 and 7.0, with pH 5.0 being close to optimal for stability of all. Temperature optima for activity ranged between 45 and 65 degrees C, with the stability optimum between 45 and 50 degrees C. The presence of C18 fatty acids and surfactants resulted in increased production of both endoglucanase and exoglucanase in the medium. Oleic acid was the most effective fatty acid tested, and Tween 80 the most effective surfactant. Oleic acid had no detectable effect on production of beta-glucosidase, and Tween 80 actually reduced its production.     

吗啡耐受大鼠心房心钠素的释放及其基因转录

本工作应用心钠素放射免疫测定和分子杂交技术首次发现,吗啡耐受大鼠血浆心钠素水平显著降低,心房内心钠素含量明显升高,同时心房内心钠素特异性mRNA水平也相应提高,提示在吗啡耐受时大鼠心房内心钠素的合成和贮存增加,释放减少。     

Conformational flexibility and folding of synthetic peptides representing an interdomain segment of polypeptide chain in the pyruvate dehydrogenase multienzyme complex of Escherichia coli

Synthetic peptides (32 residues in length) were synthesized with amino acid sequences identical to, or related to, the long (alanine + proline)-rich region of polypeptide chain that links the innermost lipoyl domain to the dihydrolipoamide dehydrogenase-binding domain in the dihydrolipoyl acetyltransferase component of the pyruvate dehydrogenase multienzyme complex of Escherichia coli. The 400-MHz 1H NMR spectra of the peptide (Mr approximately 2800) closely resembled the sharp resonances in the spectrum of the intact complex (Mr approximately 5 x 10(6], and the apparent pKa (6.4) of the side chain of a histidine residue in one of the peptides was found to be identical to that previously observed for a histidine residue inserted by site-directed mutagenesis into the corresponding position in the same (alanine + proline)-rich region of a genetically reconstructed enzyme complex. These results strongly support the view that the three long (alanine + proline)-rich regions of the dihydrolipoyl acetyltransferase chains are exposed to solvent and enjoy substantial conformational flexibility in the enzyme complex. More detailed analysis of the peptides by circular dichroism and by 1H and 13C NMR spectroscopy revealed that they were disordered in structure but were not random coils. In particular, all the Ala-Pro peptide bonds were greater than 95% in the trans configuration, consistent with a stiffening of the peptide structure. Differences in the sequences of the three long (alanine + proline)-rich segments may reflect structural tuning of these segments to optimize lipoyl domain movement in enzyme catalysis.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.