Does paternity or paternal investment determine the level of paternal care and does female choice explain egg stealing in the fifteen-spined stickleback?

An earlier field study on the fifteen-spined stickleback (Spinachia spinachia) showed that frequent male—male interactionsresult in high frequencies of sneaking and egg stealing. Moreover,sneaking behavior was performed not only by males adoptingalternative mating strategies, but also by males with theirown nests. The advantage of sneaking is easily understood, but it is more difficult to explain the evolutionary benefitof stealing eggs from other males. I investigated whether malessuffering from sneaking adjust their paternal effort in relationto their degree of paternity. I also examined whether femalesprefer males that have more eggs in their nests, as this couldexplain egg stealing. There was no relationship between thedegree of paternity and fanning activity, hatching success,or nest defense. However, the older the eggs become, the morethe males increase their attack rate toward potential egg predators(goldsinny wrasse and shore crabs). Thus, males adjusted theirlevel of defense to the amount of energy and time already investedin the clutch. Females did not prefer males with more eggs intheir nests. On the contrary, females preferred males withreduced clutches over males with enlarged clutches. Therefore,female choice is unlikely to be a driving force behind eggstealing in this species.     

Cat satellite DNA. Isolation using netropsin with CsCl gradients

The absence of centromeric bands in the karyotype of Felis catus is confirmed. It is also confirmed that no satellite band is visible in CsCl density gradients. However, a satellite is observed both by recentrifuging the fraction of the DNA that bands at high density in CsCl and by using netropsin to enhance the resolution of a CsCl gradient containing total F. catus DNA. The satellite, about 0.5% of total DNA, was isolated by repeated centrifugation in CsCl alone and in CsCl with netropsin. Netropsin was removed and a pure satellite DNA obtained. The reassociation kinetics (C0t1/2 less than 10(-3) M . s) show that the satellite is of the simple sequence type and hence a candidate for centromeric heterochromatin. Its cytological localisation awaits in situ hybridisation experiments.     

High Rates of Obesity and Chronic Disease Among United Methodist Clergy

We used self‐reported data from United Methodist clergy to assess the prevalence of obesity and having ever been told certain chronic disease diagnoses. Of all actively serving United Methodist clergy in North Carolina (NC) 95% (n = 1726) completed self‐report height and weight items and diagnosis questions from the Behavioral Risk Factor Surveillance Survey (BRFSS). We calculated BMI categories and diagnosis prevalence rates for the clergy and compared them to the NC population using BRFSS data. The obesity rate among clergy aged 35–64 years was 39.7%, 10.3% (95% CI = 8.5%, 12.1%) higher than their NC counterparts. Clergy also reported significantly higher rates of having ever been given diagnoses of diabetes, arthritis, high blood pressure, angina, and asthma compared to their NC peers. Health interventions that address obesity and chronic disease among clergy are urgently needed.     

Lactose repressor protein modified with dansyl chloride: activity effects and fluorescence properties

Chemical modification using 5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl chloride) has been used to explore the importance of lysine residues involved in the binding activities of the lactose repressor and to introduce a fluorescent probe into the protein. Dansyl chloride modification of lac repressor resulted in loss of operator DNA binding at low molar ratios of reagent/monomer. Loss of nonspecific DNA binding was observed only at higher molar ratios, while isopropyl beta-D-thiogalactoside binding was not affected at any of the reagent levels studied. Lysine residues were the only modified amino acids detected. Protection of lysines-33 and -37 from modification by the presence of nonspecific DNA correlated with maintenance of operator DNA binding activity, and reaction of lysine-37 paralleled operator binding activity loss. Energy transfer between dansyl incorporated in the core region of the repressor protein and tryptophan-201 was observed, with an approximate distance of 23 A calculated between these two moieties.     

Comparison of cobalamin-independent and cobalamin-dependent methionine synthases from Escherichia coli: two solutions to the same chemical problem.

In Escherichia coli, two enzymes catalyze the synthesis of methionine from homocysteine using methyltetrahydrofolate as the donor of the required methyl group: cobalamin-dependent and cobalamin-independent methionine synthases. Comparison of the mechanisms of these two enzymes offers the opportunity to examine two different solutions to the same chemical problem. We initiated the research described here to determine whether the two enzymes were evolutionarily related by comparing the deduced amino acid sequences of the two proteins. We have determined the nucleotide sequence for the metE gene, encoding the cobalamin-independent methionine synthase. Our results reveal an absence of similarity between the deduced amino acid sequences of the cobalamin-dependent and cobalamin-independent proteins and suggest that the two have arisen by convergent evolution. We have developed a rapid one-step purification of the recombinant cobalamin-independent methionine synthase (MetE) that yields homogeneous protein in high yield for mechanistic and structural studies. In the course of these studies, we identified a highly reactive thiol in MetE that is alkylated by chloromethyl ketones and by iodoacetamide. We demonstrated that alkylation of this residue, shown to be cysteine 726, results in complete loss of activity. While we are unable to deduce the role of cysteine 726 in catalysis at this time, the identification of this reactive residue suggests the possibility that this thiol functions as an intermediate methyl acceptor in catalysis, analogous to the role of cobalamin in the reaction catalyzed by the cobalamin-dependent enzyme.     

Reproductive activity and physiological status of the calanoid copepods Calanus helgolandicus and Calanoides carinatus under food-limiting conditions

The reproductive activity and the physiological state of the calanoid copepods Calanus helgolandicus and Calanoides carinatus were investigated off the coast of NW Spain during autumn to evaluate the effect of short food resources on both populations. Phytoplankton biomass was low, and neither phytoplankton size distribution nor composition was suitable to support high reproductive rates. Accordingly, egg production rates (EPR) were much lower than maximum rates for both species, pointing to food limitation. The reproductive index (RI), which represents the proportion of females with mature gonads, was < 50% at each of the three zones into which the sampling area was divided (coast, shelf and ocean). Potential recruitment rates were very low except at some nearshore stations, where the highest concentrations of chlorophyll-a (Chl-a), diatoms, dinoflagellates and large cells were found. EPR of C. helgolandicus and C. carinatus were correlated with phytoplankton biomass and unaffected by temperature. Phytoplankton carbon ingestion explained ca. 50% of the variability in EPR for both species. At most of the stations, herbivory was insufficient to cover the carbon requirements for reproduction and respiration, so females probably fed on heterotrophic prey to meet their demands. However, given the low fecundity observed, this omnivorous diet did not seem to be optimum for reproduction, and a severe food limitation is thus suggested. Furthermore, the high C/N values measured point to a notable lipid storage, but given the low EPR found, lipid reserves were probably invested into female maintenance rather than into gonad maturation. C. helgolandicus and C. carinatus populations did not mirror phytoplankton biomass distribution, but they correlated well when considering only copepodites V (CV). The CV could be preparing for the overwintering, storing lipid reserves to ensure a successful diapause, and they could also be advected by the poleward current detected during the study. Females showed a diel feeding rhythm, with highest ingestion rates during night. From our results, it follows that C. helgolandicus and C. carinatus females did not perform diel vertical migrations. We suggest that this behaviour is likely due to the food-limiting conditions, which make it more advantageous to remain at the surface during daytime.