Seasonal effects on metabolism and thermoregulation abilities of the Red-winged Starling (Onychognathus morio)

Basal metabolic rate (BMR) of birds is beginning to be viewed as a highly flexible physiological trait influenced by environmental fluctuations, and in particular changes in ambient temperatures (T_a). Southern Africa is characterized by an unpredictable environment with daily and seasonal variation. This study sought to evaluate the effects of seasonal changes in T_a on mass-specific resting metabolic rate (RMR), BMR and body temperature (T_b) of Red-winged Starlings (Onychognathus morio). They have a broad distribution, from Ethiopia to the Cape in South Africa and are medium-sized frugivorous birds. Metabolic rate (VO₂) and T_b were measured in wild caught Red-winged Starlings after a period of summer and winter acclimatization in outdoor aviaries. RMR and BMR were significantly higher in winter than summer. Body mass of Starlings was significantly higher in winter compared with summer. The increased RMR and BMR in winter indicate improved ability to cope with cold and maintenance of a high T_b. These results show that the metabolism of Red-winged Starlings are not constant, but exhibit a pronounced seasonal phenotypic flexibility with maintenance of a high T_b.     

Population policies,programmes and the environment

Human consumption is depleting the Earth''s natural resources and impairing the capacity of life-supporting ecosystems. Humans have changed ecosystems more rapidly and extensively over the past 50 years than during any other period, primarily to meet increasing demands for food, fresh water, timber, fibre and fuel. Such consumption, together with world population increasing from 2.6 billion in 1950 to 6.8 billion in 2009, are major contributors to environmental damage. Strengthening family-planning services is crucial to slowing population growth, now 78 million annually, and limiting population size to 9.2 billion by 2050. Otherwise, birth rates could remain unchanged, and world population would grow to 11 billion. Of particular concern are the 80 million annual pregnancies (38% of all pregnancies) that are unintended. More than 200 million women in developing countries prefer to delay their pregnancy, or stop bearing children altogether, but rely on traditional, less-effective methods of contraception or use no method because they lack access or face other barriers to using contraception. Family-planning programmes have a successful track record of reducing unintended pregnancies, thereby slowing population growth. An estimated $15 billion per year is needed for family-planning programmes in developing countries and donors should provide at least $5 billion of the total, however, current donor assistance is less than a quarter of this funding target.     

城镇用地扩张对城市热环境的影响

以快速城市化的典型区域广东省东莞市为例,以Landsat/TM、ETM~+为主要数据源,采用单窗算法反演地表温度,提出多时相数据标准化处理方法,构建相对热效应指数、热贡献指数、冷贡献指数,定量研究城镇用地扩张对城市热环境的影响.结果表明:1990-2005年,东莞市城镇用地扩张迅猛,高温区由岛状向带状再向面状扩张.城镇用地的相对热效应指数先增大后减小,1990年为0.6,2000年为1.0,2005年为0.6;热贡献指数持续增长,1990年为4.5%、2000年为38.4%,2005年为62.9%;冷贡献指数逐步增长,1990年为1.2%,2000年为1.8%,2005年为6.8%.

Abstract：

Taking the rapidly urbanized Dongguan City of Guangdong as a ease, and by using Landsat/TM and ETM~+ data, the land surface temperature (LST) was retrieved via mono-win-dow algorithm. A standardized method for treating the LST was proposed, and three thermal envi-ronment indices (relative thermal effect index, heat contribution index, and cold contribution in-dex) were built to quantitatively study the effects of urban land expansion on urban thermal envi-ronment. In 1990-2005, the urban land area in Dongguan had a rapid expansion, and the high temperature zone expanded from island-shape to belt-shape and then to lamina-shape. The rela-tive thermal effect index of urban land decreased after an initial increase, being 0. 6 in 1990,1.0 in 2000, and 0. 6 in 2005. The heat contribution index increased persistently, which was 4. 5% in 1990, 38.4% in 2000, and 62.9% in 2005, and the cold contribution index increased gradually, which was 1.2% in 1990, 1.8% in 2000, and 6. 8% in 2005.     

Dynamic of phytoplankton size-class and photosynthetic activity in a tropical hypereutrophic lake: the Yaounde municipal lake (Cameroon)

This study carried out within the framework of a multi-disciplinary project, aimed at highlighting the fundamental processes governing the functioning of the hypertrophic Yaoundé Municipal Lake. It was based on the hypothesis that, even within a small range of lake trophic status, important variations can occur in the species composition, biomass and photosynthetic activity of the phytoplankton size-fractions. For this purpose, samples were taken at weekly intervals from November 1996 to December 1997 at a fixed set of depths in the water column. Spatial-temporal fluctuations of some physical–chemical variables, associated with biological variables such as phytoplankton size-class species composition, phytoplankton size-class biomass, phytoplankton primary production and chlorophyll-a were analysed. The water transparency was low and rarely exceeded 100 cm. Conductivity values relatively higher increased generally from the top to the lake bottom. The oxygen deficiency, and sometimes anoxia, recorded from 2.5 m depth resulted in high quantities of ammonium nitrogen. Total phosphorus and total Kjeldahl nitrogen concentrations were characteristics of hypertrophic lakes. The fertility of this biotope favoured the development of a high phytoplanktonic community with remarkable physiological adaptations to the variations of the nutritive potentials of the lake, characterized by the size-structure of these organisms. Cells of small size (<12 μm) contributed up to 11.42% of the total phytoplanktonic biomass. Species with average size (12–45 μm), dominated by Chlamydomonas spp., represented a more significant contribution reaching up to 69.85%, whereas the cells of big size (>45 μm), mainly Euglenophyta, maintained the relatively most important biomass, accounting for up to 89.85% of the total phytoplanktonic biomass. Chlorophyll-a concentrations are among the highest reported for both fresh water and sea water, being a consequence of high proportions of Chlorophyta and Euglenophyta. This led to intense phytoplanktonic photosynthetic activity which continued throughout the year, even though it was confined to the upmost first meter of the water column. Analyses pointed out the allogenic nature of the functioning of this urban lake ecosystem, due to a poor waste management on the surrounding landscape. Handling editor: J. Padisak     

THE EVOLVABILITY OF GROWTH FORM IN A CLONAL SEAWEED

Although modular construction is considered the key to adaptive growth or growth‐form plasticity in sessile taxa (e.g., plants, seaweeds and colonial invertebrates), the serial expression of genes in morphogenesis may compromise its evolutionary potential if growth forms emerge as integrated wholes from module iteration. To explore the evolvability of growth form in the red seaweed, Asparagopsis armata, we estimated genetic variances, covariances, and cross‐environment correlations for principal components of growth‐form variation in contrasting light environments. We compared variance–covariance matrices across environments to test environmental effects on heritable variation and examined the potential for evolutionary change in the direction of plastic responses to light. Our results suggest that growth form in Asparagopsis may constitute only a single genetic entity whose plasticity affords only limited evolutionary potential. We argue that morphological integration arising from modular construction may constrain the evolvability of growth form in Asparagopsis, emphasizing the critical distinction between genetic and morphological modularity in this and other modular taxa.     

The intimate and mysterious relationship between proton channels and NADPH oxidase

Voltage gated proton channels and NADPH oxidase function cooperatively in phagocytes during the respiratory burst, when reactive oxygen species are produced to kill microbial invaders. Although these molecules are distinct entities, with no proven physical interaction, their presence and activity in many cells appears to be coordinated. We describe these interactions and discuss several types of mechanisms that might explain them.     

Detection of quantitative trait loci for heading date based on the doubled haploid progeny of two elite Chinese wheat cultivars

Quantitative trait loci (QTLs) with epistatic and QTL × environment (QE) interaction for heading date were studied using a doubled haploid (DH) population containing 168 progeny lines derived from a cross between two elite Chinese wheat cultivars Huapei 3 × Yumai 57 (Triticum aestivum L.). A genetic map was constructed based on 305 marker loci, consisting of 283 SSR loci and 22 EST-SSR markers, which covered a total length of 2141.7 cM with an average distance of 7.02 cM between adjacent markers in the genome. QTL analyses were performed using a mixed linear model approach. Two main-effect QTLs and two pairs of digenic epistatic effects were detected for heading date on chromosomes 1B, 2B, 5D, 6D, 7A, and 7D at three different environments in 2005 and 2006 cropping seasons. A highly significant QTL with an F-value 148.96, designated as Qhd5D, was observed within the Xbarc320-Xwmc215 interval on chromosome 5DL, accounting for 53.19% of the phenotypic variance and reducing days-to-heading by 2.77 days. The Qhd5D closely links with a PCR marker Xwmc215 with the genetic distance 2.1 cM, which can be used in molecular marker-assisted selection (MAS) in wheat breeding programs. Moreover, the Qhd5D was located on the similar position of well-characterised vernalization sensitivity gene Vrn-D1. We are also spending more efforts to develop near-isogenic lines to finely map the Qhd5D and clone the gene Vrn-D1 through map-based cloning. The Qhd1B with additive effect on heading date has not been reported in previous linkage mapping studies, which might be a photoperiod-sensitive gene homoeologous to the Ppd-H2 gene on chromosome 1B. No main-effect QTLs for heading date were involved in epistatic effects.     

Effect of the snail Ilyanassa obsoleta (Say) on dynamics of the amphipod Corophium volutator (Pallas) on an intertidal mudflat

We investigated interactions between two dominant invertebrate species of intertidal soft-sediment environments of the northwest Atlantic, the mud snail Ilyanassa obsoleta and the burrowing amphipod Corophium volutator, on a mudflat of the upper Bay of Fundy, Canada. Distribution of I. obsoleta on the mudflat was highly patchy and negatively correlated with density of C. volutator. Manipulation of snail density in cages showed that I. obsoleta influences C. volutator; specifically, increasing density of snails reduced density, increased patchiness in distribution, decreased recapture rates and decreased immigration of C. volutator. Ilyanassa obsoleta seems to be affecting C. volutator through an influence on survival rate and emigration rate, although temporal variation in these effects was observed. Given that both I. obsoleta and C. volutator show a preference for tide pools, an important microhabitat on mudflats, snails might have a profound impact on C. volutator population dynamics.     

RNA Chaperones Stimulate Formation and Yield of the U3 snoRNA-Pre-rRNA Duplexes Needed for Eukaryotic Ribosome Biogenesis

Short duplexes between the U3 small nucleolar RNA and the precursor ribosomal RNA must form quickly and with high yield to satisfy the high demand for ribosome synthesis in rapidly growing eukaryotic cells. These interactions, designated the U3-ETS (external transcribed spacer) and U3-18S duplexes, are essential to initiate the processing of small subunit ribosomal RNA. Previously, we showed that duplexes corresponding to those in Saccharomyces cerevisiae are only observed in vitro after addition of one of two proteins: Imp3p or Imp4p. Here, we used fluorescence-based and other in vitro assays to determine whether these proteins possess RNA chaperone activities and to assess whether these activities are sufficient to satisfy the duplex yield and rate requirements expected in vivo. Assembly of both proteins with the U3 small nucleolar RNA into a chaperone complex destabilizes a U3 stem structure, apparently to expose its 18S base-pairing site. As a result, the chaperone complex accelerates formation of the U3-18S duplex from an undetectable rate to one comparable with the intrinsic rate observed for hybridizing short duplexes. The chaperone complex also stabilizes the U3-ETS duplex by 2.7 kcal/mol. These chaperone activities provide high U3-ETS duplex yield and rapid U3-18S duplex formation over a broad concentration range to help ensure that the U3-precursor ribosomal RNA interactions limit neither ribosome biogenesis nor rapid cell growth. The thermodynamic and kinetic framework used is general and thus suitable for investigating the mechanism of action of other RNA chaperones.     

Paternal deprivation induces dendritic and synaptic changes and hemispheric asymmetry of pyramidal neurons in the somatosensory cortex

Similar to maternal care, paternal care is a source of neonatal sensory stimulation, which in primates and rodents has been shown to be essential for developing structure and function of sensory cortices. The aim of our study in the biparental rodent Octodon degus was to assess the impact of paternal deprivation on dendritic and synaptic development in the somatosensory cortex. We (i) quantified the amount of paternal care in relation to total parental investment and (ii) compared dendritic and synaptic development of pyramidal neurons in the somatosensory cortex of animals raised by a single mother or by both parents. On the behavioral level we show that paternal care comprises 37% of total parent‐offspring interactions, and that the somatosensory stimulation provided by the fathers primarily consists of huddling, licking/grooming, and playing. On the morphological level we found that, compared with offspring raised by both parents (mother and father), the father‐deprived animals displayed significantly reduced spine numbers on the basal dendrites of pyramidal neurons. Furthermore, paternal deprivation induces hemispheric asymmetry of the dendritic morphology of somatosensory pyramidal neurons. Father‐deprived animals show shorter and less complex basal dendrites in the left somatosensory cortex compared with the right hemisphere. These findings indicate that paternal deprivation results in delayed or retarded dendritic and synaptic development of somatosensory circuits. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009