Distribution of pelagic larvae of benthic marine invertebrates in the Bellingshausen Sea

During November and December 1992, plankton samples were collected using a ring net of mesh size 200 m vertically hauled through a 600 m water column, at five stations along a transect running north from the Allison Peninsula in the Bellingshausen Sea. Three stations were located over the continental shelf; two of these were ice bound, whilst the third was at the ice edge. Two other stations were in deeper, ice-free water. Sixteen different larval and juvenile types were found representing seven phyla: Echinodermata, Nemertea, Coelenterata, Mollusca, Annelida, Arthropoda and Bryozoa, of which the first two were the most abundant. Larval numbers and types decreased with distance offshore and away from permanent sea ice. The presence of many stages of nemertean larval development within a short time scale, in an area where developmental tends to be slow, suggests that reproduction occurs over an extended period and that the larvae have a long planktonic phase. The increased size of later developmental stages of the nemertean larvae indicates they obtain nutrition within the water column during winter, when little particulate food is present.     

The cytochromes of mitochondria from Tetrahymena pyriformis strain ST

1. Mitochondria of the obligately aerobic ciliate protozoon, Tetrahymena pyriformis strain ST, are unusual in that they possess a cytochrome oxidase system that does not react with reduced mammalian cytochrome c; the presence of cytochromes a₆₀₃+a₃ is masked in the α-band region of spectra by the broad absorption band of cytochrome a₆₂₀. 2. Other haemoproteins present include cytochromes b₅₆₀, b₅₅₆, c₅₅₃ and c₅₄₉. 3. The reaction of reduced cytochrome a₃ with CO is reversed by flash photolysis, and in the presence of O₂ the subsequent oxidation of this cytochrome is followed by that of cytochrome a₆₀₃. 4. Cytochromes a₆₂₀ and b₅₆₀ also react with CO and with KCN; the latter cytochrome corresponds with that designated cytochrome o by other workers. 5. The contribution of cytochrome a₆₀₃ to difference spectra is revealed by making use of the fact that it does not react with KCN. 6. Cytochrome a₆₂₀ is unstable, and its α-absorption band is lost from spectra of mitochondria which have been aged or treated with ultrasound, detergents or organic solvents. 7. Possible pathways of electron transport via the several different terminal oxidases in Tetrahymena mitochondria are proposed.     

Habituation and habitat changes can moderate the impacts of human disturbance on shorebird breeding performance

Disturbance by humans is widely expected to reduce the reproductive fitness of nesting birds if disturbance reduces nest attentiveness, and unattended eggs experience increased risk of predation or exposure to potentially lethal temperature extremes. Yet, relatively few studies have examined the physiological or behavioural mechanisms whereby disturbance influences reproductive fitness, or the extent to which the costs of disturbance may be reduced through habituation. We compared the behavioural responses, egg temperatures and reproductive success of shore-nesting white-fronted plovers Charadrius marginatus to disturbance at two breeding sites experiencing low versus high human recreational activity, respectively. Daytime nest attentiveness decreased with increasing experimental disturbance at both sites, but this relationship differed between sites; for any given level of disturbance, incubating birds at the more disturbed site had greater nest attentiveness. They achieved this through habituation, allowing a closer human approach before leaving the nest, and returning to the nest faster after a disturbance event. Despite lower average daytime nest attentiveness at the more disturbed site, incubation temperatures did not differ significantly between sites. Nest mortality, mostly by natural mammalian and corvid predators, was significantly lower at the site experiencing high recreational activity. However, chick mortality was significantly greater at the more disturbed site, most likely because of predation by domestic dogs. Chick mortality may have been increased by the habitation of chicks, whose escape responses were much reduced at the more disturbed site. Nonetheless, annual fecundity was substantially higher at the more disturbed site, showing that the overall reproductive fitness of wild birds is not always compromised by human disturbance and urbanization.     

Role of maternal provisioning in controlling interpopulation variation in hatching size in the marine snail Nucella ostrina

This study examined the role of maternal provisioning in controlling interpopulation variation in hatching size in nine isolated populations of the intertidal gastropod Nucella ostrina, in which development to the early juvenile stage takes place within an egg capsule. Variation among populations was almost entirely due to the ratio of nurse eggs to embryo, which explained 65% of the variation in hatching size. Egg size was not a significant predictor of hatching size. Differences among seven of these populations in the nurse egg/embryo ratio were entirely due to the number of nurse eggs allocated per capsule; these populations allocated different numbers of nurse eggs per capsule but allocated the same number of embryos. Intriguingly, the two most wave-sheltered populations allocated significantly more nurse eggs and more embryos to each capsule than did the seven other populations, but they maintained nurse egg/embryo ratios consistent with patterns observed in the other populations. Inter- and intrapopulation variation in hatching size appears to be controlled largely by different mechanisms: within-population variation being controlled mainly by differences in allocation of embryos per capsule, whereas most among-population variation being due to differences in allocation of nurse eggs per capsule.     

The role of WWP1-Gag interaction and Gag ubiquitination in assembly and release of human T-cell leukemia virus type 1

The PPPY motif in the matrix (MA) domain of human T-cell leukemia virus type 1 (HTLV-1) Gag associates with WWP1, a member of the HECT domain containing family of E3 ubiquitin ligases. Mutation of the PPPY motif arrests particle assembly at an early stage and abolishes ubiquitination of MA. Similar effects are seen when Gag is expressed in the presence of a truncated form of WWP1 that lacks the catalytically active HECT domain (C2WW). To understand the role of ubiquitination in budding, we mutated the four lysines in MA to arginines and identified lysine 74 as the unique site of ubiquitination. Virus-like particles produced by the K74R mutant did not contain ubiquitinated MA and showed a fourfold reduction in the release of infectious particles. Furthermore, the K74R mutation rendered assembly hypersensitive to C2WW inhibition; K74R Gag budding was inhibited at significantly lower levels of expression of C2WW compared with wild-type Gag. This finding indicates that the interaction between Gag and WWP1 is required for functions other than Gag ubiquitination. Additionally, we show that the PPPY⁻ mutant Gag exerts a strong dominant-negative effect on the budding of wild-type Gag, further supporting the importance of recruitment of WWP1 to achieve particle assembly.     

Inter-species variation in the oligomeric states of the higher plant Calvin cycle enzymes glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase

In darkened leaves the Calvin cycle enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK) form a regulatory multi-enzyme complex with the small chloroplast protein CP12. GAPDH also forms a high molecular weight regulatory mono-enzyme complex. Given that there are different reports as to the number and subunit composition of these complexes and that enzyme regulatory mechanisms are known to vary between species, it was reasoned that protein-protein interactions may also vary between species. Here, this variation is investigated. This study shows that two different tetramers of GAPDH (an A2B2 heterotetramer and an A4 homotetramer) have the capacity to form part of the PRK/GAPDH/CP12 complex. The role of the PRK/GAPDH/CP12 complex is not simply to regulate the 'non-regulatory' A4 GAPDH tetramer. This study also demonstrates that the abundance and nature of PRK/GAPDH/CP12 interactions are not equal in all species and that whilst NAD enhances complex formation in some species, this is not sufficient for complex formation in others. Furthermore, it is shown that the GAPDH mono-enzyme complex is more abundant as a 2(A2B2) complex, rather than the larger 4(A2B2) complex. This smaller complex is sensitive to cellular metabolites indicating that it is an important regulatory isoform of GAPDH. This comparative study has highlighted considerable heterogeneity in PRK and GAPDH protein interactions between closely related species and the possible underlying physiological basis for this is discussed.     

Microbial reduction of technetium by Escherichia coli and Desulfovibrio desulfuricans: enhancement via the use of high-activity strains and effect of process parameters

Escherichia coli and Desulfovibrio desulfuricans reduce Tc(VII) (TcO(4)(-)) with formate or hydrogen as electron donors. The reaction is catalyzed by the hydrogenase component of the formate hydrogenlyase complex (FHL) of E. coli and is associated with a periplasmic hydrogenase activity in D. desulfuricans. Tc(VII) reduction in E. coli by H(2) and formate was either inhibited or repressed by 10 mM nitrate. By contrast, Tc(VII) reduction catalyzed by D. desulfuricans was less sensitive to nitrate when formate was the electron donor, and unaffected by 10 mM or 100 mM nitrate when H(2) was the electron donor. The optimum pH for Tc(VII) reduction by both organisms was 5.5 and the optimum temperature was 40 degrees C and 20 degrees C for E. coli and D. desulfuricans, respectively. Both strains had an apparent K(m) for Tc(VII) of 0.5 mM, but Tc(VII) was removed from a solution of 300 nM TcO(4)(-) within 30 h by D. desulfuricans at the expense of H(2). The greater bioprocess potential of D. desulfuricans was shown also by the K(s) for formate (>25 mM and 0.5 mM for E. coli and D. desulfuricans, respectively), attributable to the more accessible, periplasmic localization of the enzyme in the latter. The relative rates of Tc(VII) reduction for E. coli and D. desulfuricans (with H(2)) were 12.5 and 800 micromol Tc(VII) reduced/g biomass/h, but the use of an E. coli HycA mutant (which upregulates FHL activities by approx. 50%) had a similarly enhancing effect on the rate of Tc reduction. The more rapid reduction of Tc(VII) by D. desulfuricans compared with the E. coli strains was also shown using cells immobilized in a hollow-fiber reactor, in which the flow residence times sustaining steady-state removal of 80% of the radionuclide were 24.3 h for the wild-type E. coli, 4.25 h for the upregulated mutant, and 1.5 h for D. desulfuricans.     

Survival and growth of two heterotrophic hydrothermal vent archaea, <Emphasis Type="Italic">Pyrococcus</Emphasis> strain GB-D and <Emphasis Type="Italic">Thermococcus fumicolans</Emphasis>, under low pH and high sulfide concentrations in combination with high temperature and pressure regimes

Growth and survival of hyperthermophilic archaea in their extreme hydrothermal vent and subsurface environments are controlled by chemical and physical key parameters. This study examined the effects of elevated sulfide concentrations, temperature, and acidic pH on growth and survival of two hydrothermal vent archaea (Pyrococcus strain GB-D and Thermococcus fumicolans) under high temperature and pressure regimes. These two strains are members of the Thermococcales, a family of hyperthermophilic, heterotrophic, sulfur-reducing archaea that occur in high densities at vent sites. As actively growing cells, these two strains tolerated regimes of pH, pressure, and temperature that were in most cases not tolerated under severe substrate limitation. A moderate pH of 5.5–7 extends their survival and growth range over a wider range of sulfide concentrations, temperature and pressure, relative to lower pH conditions. T. fumicolans and Pyrococcus strain GB-D grew under very high pressures that exceeded in-situ pressures typical of hydrothermal vent depths, and included deep subsurface pressures. However, under the same conditions, but in the absence of carbon substrates and electron acceptors, survival was generally lower, and decreased rapidly when low pH stress was combined with high pressure and high temperature. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Biological and socio-economic effects of statewide limitation of deer licenses in Colorado

We evaluated the biological and socio-economic effects of statewide limitation of mule deer (Odocoileus hemionus) hunting licenses, which began in Colorado in 1999. We implemented a before-after-control-impact (BACI) analysis of annual helicopter sex and age class surveys, collected as part of the Colorado Division of Wildlife's routine monitoring, to assess changes in adult male/adult female ratios and fawn/adult female ratios in response to this change in harvest management. Following statewide limitation and reduction of license sales (1999–2006), we observed increases in adult male/adult female ratios of 7.39 (SE = 2.36) to 15.23 (SE = 1.22) adult males per 100 adult females in moderately limited areas and of 17.55 (SE = 3.27) to 21.86 (SE = 2.31) adult males per 100 adult females in highly limited areas. We simultaneously observed reductions in fawn/adult female ratios in newly limited areas by as much as 6.96 (SE = 2.19) fawns per 100 females, whereas in areas that had previously been limited we observed stabilization of fawn/adult female ratios at levels lower than levels observed under the unlimited harvest management structure. An immediate decline of $7.86 million in annual revenue stemmed from the change in harvest management, but revenue subsequently rebounded. This study provides preliminary evidence of potential effects that other state and provincial wildlife management agencies may face as they consider shifting mule deer harvest management towards limited license scenarios. © 2011 The Wildlife Society.