Contrasting selection modes at the Adh1 locus in outcrossing Miscanthus sinensis vs. inbreeding Miscanthus condensatus (Poaceae)

We estimated DNA sequence variation of the Adh1 locus in the outcrossing Miscanthus sinensis (Poaceae) and its close selfing relative, M. condensatus. Tajima's test of selection is significantly negative for both overall exons and replacement sites in M. sinensis. Among its entire sample, nucleotide diversity of nonsynonymous sites is higher than that of synonymous sites. A McDonald and Kreitman test of neutrality indicates an excess of intraspecific replacement polymorphisms, suggesting possible directional selection toward advantageous mutants. However, frequent intragenic recombination suggests both purifying and positive selection is unlikely. Recent demographic expansions coupled with relaxation of purifying selection may have resulted in elevated genetic diversity at the Adh1 locus as well as the trnL-trnF intergenic spacer of cpDNA in this outcrossing species. In contrast, low levels of genetic diversity were detected at both the Adh1 locus and the cpDNA spacer in M. condensatus, consistent with bottlenecks associated with selfing in all populations. While Tajima's D and Fu and Li's F statistics did not reveal deviation from neutrality at the Adh1 locus in M. condensatus, 12 replacements vs. 10 synonymous changes were detected. Based on pairwise comparisons of the d(N)/d(S) ratio, lineages of closely related populations of the species distributed along saline habitats appeared to be under directional selection.     

Role of apoptosis and Fas/FasL system in the oogenesis of the spotted ray Torpedo marmorata

In the present paper we investigated the role played by apoptosis during oogenesis in the cartilaginous fish Torpedo marmorata. TEM, TUNEL and immunohistochemical techniques were employed to specifically reveal morphological and biochemical hallmarks of apoptosis in specimens from birth to sexual maturity. Data obtained demonstrate that apoptosis occurs in prefollicular oocyte selection, in maintaining the homeostasis of granulosa in healthy growing oocyte and in resorbing atretic follicles. In this respect, the involvement of apoptosis in Torpedo marmorata oogenesis closely parallels that found in mammals, thus confirming that strategies of germ cell selection among vertebrates have been evolutionarily preserved.     

Enhanced cytotoxicity without internuclear spread of adenovirus upon cell fusion by measles virus glycoproteins

The efficiency of viruses in cancer therapy is enhanced by proteins that mediate the fusion of infected cells with their neighbors. It was reported that replication-competent adenovirus particles can spread between nuclei within fusion-generated syncytia. To assess this conjecture, we generated fusogenic adenoviruses that express a balanced ratio of the F and H glycoproteins of measles virus. The viruses displayed enhanced cytotoxicity but largely unchanged replication efficiencies compared to a nonfusogenic virus. Most notably, the virus genomes did not spread through fusion-generated multinuclear cells. Hence, adenovirus replication in syncytia remains largely restricted to initially transduced nuclei.     

Heritable circadian period length in a wild bird population

Timing is essential, but circadian clocks, which play a crucial role in timekeeping, are almost unaddressed in evolutionary ecology. A key property of circadian clocks is their free-running period length (τ), i.e. the time taken for a full cycle under constant conditions. Under laboratory conditions, concordance of τ with the ambient light–dark cycle confers major fitness benefits, but little is known about period length and its implications in natural populations. We therefore studied natural variation of circadian traits in a songbird, the great tit (Parus major), by recording locomotor activity of 98 hand-raised, wild-derived individuals. We found, unexpectedly, that the free-running period of this diurnal species was significantly shorter than 24 h in constant dim light. We furthermore demonstrate, to our knowledge for the first time in a wild vertebrate, ample genetic variation and high heritability (h² = 0.86 ± 0.24), implying that period length is potentially malleable by micro-evolutionary change. The observed, short period length may be a consequence of sexual selection, as offspring from extra-pair matings had significantly shorter free-running periods than their half-siblings from within-pair matings. These findings position circadian clocks in the ‘real world’ and underscore the value of using chronobiological approaches in evolutionary ecology. Evolutionary ecologists study variation and its fitness consequences, but often have difficulties relating behavioural variation to physiological mechanisms. The findings presented here open the possibility that properties of internal, circadian clocks affect performance in traits that are relevant to fitness and sexual selection.     

Removal of Ca2+ channel beta3 subunit enhances Ca2+ oscillation frequency and insulin exocytosis

An oscillatory increase in pancreatic beta cell cytoplasmic free Ca2+ concentration, [Ca2+]i, is a key feature in glucose-induced insulin release. The role of the voltage-gated Ca2+ channel beta3 subunit in the molecular regulation of these [Ca2+]i oscillations has now been clarified by using beta3 subunit-deficient beta cells. beta3 knockout mice showed a more efficient glucose homeostasis compared to wild-type mice due to increased glucose-stimulated insulin secretion. This resulted from an increased glucose-induced [Ca2+]i oscillation frequency in beta cells lacking the beta3 subunit, an effect accounted for by enhanced formation of inositol 1,4,5-trisphosphate (InsP3) and increased Ca2+ mobilization from intracellular stores. Hence, the beta3 subunit negatively modulated InsP3-induced Ca2+ release, which is not paralleled by any effect on the voltage-gated L type Ca2+ channel. Since the increase in insulin release was manifested only at high glucose concentrations, blocking the beta3 subunit in the beta cell may constitute the basis for a novel diabetes therapy.     

Comparison of different probe-level analysis techniques for oligonucleotide microarrays

Three different software packages for the probe-level analysis of high-density oligonucleotide microarray data were compared using an experiment-derived data set that was validated using real-time PCR. The efficiency with which these three programs could identify true positives in this data set was assessed. In addition, estimates of false-positive and false-negative rates were determined. The performance of the programs using very small data sets was also compared, and recommendations for use are suggested.     

Heavy metal ions inhibition of jack bean urease: potential for rapid contaminant probing

The kinetics of heavy metal ions inhibition of jack bean urease was studied by progress curve analysis in a reaction system without enzyme-inhibitor preincubation. The inhibition was found to be biphasic with an initial, small inhibitory phase changing over the time course of 5-10 min into a final linear steady state with a lower velocity. This time-dependent pattern was best described by mechanism B of slow-binding inhibition, involving the rapid formation of an EI complex that subsequently undergoes slow conversion to a more stable EI* complex. The kinetic parameters of the process, the inhibition constants Ki and Ki* and the forward k5 and reverse k6 rate constants for the conversion, were evaluated from the reaction progress curves by nonlinear regression treatment. Based on the values of the overall inhibition constant Ki*, the heavy metal ions were found to inhibit urease in the following decreasing order: Hg2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+ > Pb2+ > Co2+ > Fe3+ > As3+. With the Ki* values as low as 1.9 nM for Hg2+ and 7.1 nM for Cu2+, 100-1000 times lower than those of the other ions, urease may be utilized as a bioindicator of the trace levels of these ions in environmental monitoring, bioprocess control or pharmaceutical analysis.     

Social behavior of infant and mother Japanese Macaques (Macaca fuscata): Effects of kinship,partner sex,and infant sex

The behavioral interactions of 22 infant and mother Japanese macaques with other group members were studied. Focal-animal observations were made from the time of each infant’s birth until 1 year of age. Infants and mothers both displayed exceedingly strong preferences for associating with matrilineal kin and, specifically, for female kin. The degree of genetic relatedness was positively correlated with levels of spatial proximity, contact, grooming, aggression, and play. Overall frequencies of interactions with nonkin were very low, and partner sex was not an important factor in interactions with nonkin. There were no significant differences between male and female infants in interactions with kin versus nonkin. There was only one significant difference between male and female infants in interactions with males versus females: female infants showed stronger preferences for initiating proximity with females over males than did male infants. Because mothers provide the focal point for infant interactions during the first year of life, we compared the behavior of infants and mothers. Mothers were the recipients of more social interactions than were infants, mothers engaged in more grooming than did infants, and infants engaged in more social play than did mothers. These findings are only partially consistent with kin-selection theory, and the inadequacies of studying matrilineal kin discrimination to test kin selection are reviewed. The near-absence of infant sex differences in associations with social partners suggests that although maternal kin other than the mother are important to infant socialization, they probably do not contribute to the development of behavioral sex differences until after the first year of life.     

Methylammonium uptake by Rhodobacter capsulatus

The ammonium uptake system of Rhodobacter capsulatus B100 was examined using the ammonium analog methylammonium. This analog was not transported when cells were grown aerobically on ammonium. When cultured on glutamate as a nitrogen source, or when nitrogen-starved, cells would take up methylammonium. Therefore, in cells grown under nitrogen-limiting conditions, a second system of ammonium uptake (or a modified form of the first) is present which is distinguished by its capacity for transporting the analog in addition to ammonium. The methylammonium uptake system exhibited saturation kinetics with a K _m of 22 M and a V _max of about 3 nmol per min · mg protein. Ammonium completely inhibited analog transport with a K _i in the range of 1 M. Once inside the cell methylammonium was rapidly converted to -N-methylglutamine; however, a small concentration gradient of methylammonium could still be observed. Kinetic parameters reflect the effects of assimilation.The methylammonium uptake system was temperature and pH dependent, and inhibition studies indicated that energy was required for the system to be operative. A glutamine auxotroph (G29) lacking the structural gene for glutanime synthetase did not accumulate the analog, even when nitrogen starved. The Nif^- mutant J61, which is unable to express nitrogenase structural genes, also did not transport methylammonium, regardless of the nitrogen source for growth. However, the mutant exhibited wild-type ammonium uptake and glutamine synthetase activity. These data suggest that transport of ammonium is required for growth on limited nitrogen and is under the control of the Ntr system in R. capsulatus.Abbreviations CCCP carbonyl cyanide-m-chlorophenyl hydrazone - CHES cyclohexylaminoethanesulfonic acid - DMSO dimethyl sulfoxide - GMAD -N-methylglutamine - GS glutamine synthetase - MES 2-(N-morpholino) ethanesulfonic acid - MSX methionine-Dl-sulfoximine - pCMB p-chloromercuribenzoate - Tricine N-tris(hydroxymethyl)methylglycine     

Pollen from tree and shrub taxa in the atmosphere of Caxias do Sul (Rio Grande do Sul, Brazil)

An aerobiological study has been carried out in the region of Caxias do Sul in southern Brazil. Pollen monitoring was performed from January 1, 2001 through to December 31, 2002. A total of 30,469 pollen grains were collected during this period, and 40 pollen types were identified; of these, 23,389 pollen grains, representing 29 pollen types, originated from tree and shrub taxa. The maximum pollen concentration was registered in August 2001 and October 2002. In the study area, the pollen type Mimosa scabrella (18.8%) was much more abundant than all of the pollen types from tree and shrub taxa, such as: Urticaceae (18.4%), Myrtaceae (10.2%), Cupressaceae (7.7%), Myrsine (4.8%), Sorocea (3.9%), Pinaceae (2.9%), Asteraceae (2.2%) and Ricinus (2.1%). These nine pollen types accounted for the largest pollen concentrations of all the tree and shrub taxa. The pollen types Carya, Melastomataceae, Mimosa scabrella, Myrsine and Sorocea are reported for the first time in an aerobiological study in Brazil.