Vertical profiles of DIN,DOC, and microbial activities in the wetland soil of Kushiro Mire,northeastern Japan

Kushiro Mire is the largest mire in Japan and in 1980 was the first wetland in Japan registered under the Ramsar Convention. Recent reports indicate an increase in nutrient loading into Kushiro Mire from changes in land use. We measured vertical profiles of dissolved inorganic nitrogen (DIN; NO₃ ^–, NO₂ ^–, NH₄ ⁺), dissolved organic carbon (DOC), and various types of microbial activity in soil samples collected to approximately 1.5 m deep at two sites in Kushiro Mire. We found an accumulation of NO₃ ^– and DOC in the deeper soil. Denitrifying activity was highest in the shallower soils and decreased drastically with depth, whereas higher levels of fluoresceindiacetate hydrolysis, β-glucosidase, acid phosphatase, and xylosidase enzyme activity were found in the deeper layers. We also detected humic-like substances as components of the DOC. These results suggest that the DOC in the wetland soil cannot be used as a substrate for denitrification, causing denitrification to be suppressed in the deeper soil. In addition, denitrifying activity would be very low in the deeper layers due to low soil temperature. As a result, nitrogen input to the mire has resulted in a large accumulation of NO₃ ^– in the deeper soil. This will eventually change the mire ecosystem through effects such as increased eutrophication and acidification.     

Diet of Starling Sturnus vulgaris nestlings on farmland: the importance of Tipulidae larvae

Capsule?Tipulidae larvae are a key resource for adult Starlings provisioning their young on lowland farmland.

Aims?(i) To describe Starling nestling diet on lowland farmland. (ii) To examine the effects of brood size variation and nestling age on Starling parental food provisioning.

Methods?Over 4 years, we observed parental food provisioning at 42 nests across 4 sites on lowland farmland in Oxfordshire, UK using nestbox video recorders.

Results?Tipulidae larvae were the most frequent prey item recorded in provisioning loads (52%), the next most frequent were winged insects (11%), then Coleoptera larvae (6%), Lepidoptera larvae (5%) and Lumbricidae (5%), with 21% of prey unidentified. Estimates of prey lengths, dry mass and total energy content also confirmed that Tipulidae larvae were the key prey source. Generalized linear mixed-effects models showed that larger broods received fewer Tipulidae larvae per nestling per day and that the proportion of Tipulidae larvae in the diet did not vary with brood size or nestling age.

Conclusion?Our results support the idea that Tipulidae larvae are the primary dietary item for nestling Starlings on lowland farmland.     

Greater prairie chickens have a compact MHC-B with a single class IA locus

The major histocompatibility complex (MHC) plays a central role in innate and adaptive immunity, but relatively little is known about the evolution of the number and arrangement of MHC genes in birds. Insights into the evolution of the MHC in birds can be gained by comparing the genetic architecture of the MHC between closely related species. We used a fosmid DNA library to sequence a 60.9-kb region of the MHC of the greater prairie chicken (Tympanuchus cupido), one of five species of Galliformes with a physically mapped MHC. Greater prairie chickens have the smallest core MHC yet observed in any bird species, and major changes are observed in the number and arrangement of MHC loci. In particular, the greater prairie chicken differs from other Galliformes in the deletion of an important class I antigen binding gene. Analysis of the remaining class IA gene in a population of greater prairie chickens in Wisconsin, USA revealed little evidence for selection at the region responsible for antigen binding.     

Detection of protein kinase substrates in tissue extracts after separation by isoelectric focusing

Here we report a simple and useful method to detect endogenous substrates of protein kinases. When crude tissue extracts were resolved by liquid-phase isoelectric focusing (MicroRotofor) and the separated protein fractions were phosphorylated by protein kinases such as Ca²⁺/calmodulin-dependent protein kinase I or cAMP-dependent protein kinase, various proteins in the different fractions were efficiently phosphorylated. Since a higher number of substrates could significantly be detected using the resolved fractions by MicroRotofor as compared to direct analysis of the original tissue extracts, our present method will be applicable to the screening of endogenous substrates for various protein kinases.     

Silencing of TBC1D15 promotes RhoA activation and membrane blebbing

Membrane blebs are round-shaped dynamic membrane protrusions that occur under many physiological conditions. Membrane bleb production is primarily controlled by actin cytoskeletal rearrangements mediated by RhoA. Tre2–Bub2–Cdc16 (TBC) domain-containing proteins are negative regulators of the Rab family of small GTPases and contain a highly conserved TBC domain. In this report, we show that the expression of TBC1D15 is associated with the activity of RhoA and the production of membrane blebs. Depletion of TBC1D15 induced activation of RhoA and membrane blebbing, which was abolished by the addition of an inhibitor for RhoA signaling. In addition, we show that TBC1D15 is required for the accumulation of RhoA at the equatorial cortex for the ingression of the cytokinetic furrow during cytokinesis. Our results demonstrate a novel role for TBC1D15 in the regulation of RhoA during membrane blebbing and cytokinesis.     

Do male ornaments signal immunity in the common yellowthroat?

Male ornaments may advertise genetic benefits to females choosingmates. These benefits may come in the form of genes for resistanceto parasites and disease. Thus, females that prefer more ornamentedmales as mates may receive genes for enhanced immune systemfunction for their offspring. The common yellowthroat (Geothlypistrichas) is the only species to date in which a male plumageornament (size of the black facial mask) is known to be relatedto extrapair mating, and extrapair young are more immunocompetentthan their within-pair half-sibs (at least in colder years).To investigate whether male mask size signals superior immunefunction, we examined male ornaments (mask and bib size andcolor) in relation to measures of overall health (hematocrit)and immune system function (plasma immunoglobulin G [IgG] concentrationand cutaneous immune activity). We also investigated the rolethat testosterone may play in mediating the relationship betweenornaments and immunity. Male mask size was correlated positivelywith IgG level, suggesting that male mask size may indicatehumoral immunity. However, mask size was correlated negativelywith hematocrit and cutaneous immune activity (our measure ofnestling immunocompetence). Bib size and color were not relatedto these indices of immune function or health. Plasma testosteronelevel was neither related to immune function or health nor tothe expression of male ornaments. These results suggest thatthere might be a trade-off between immune system components,as well as between immunity and the production or advertisementof male ornaments.     

Coloniality and migration are related to selection on MHC genes in birds

The major histocompatibility complex (MHC) plays a key role in pathogen recognition as a part of the vertebrate adaptive immune system. The great diversity of MHC genes in natural populations is maintained by different forms of balancing selection and its strength should correlate with the diversity of pathogens to which a population is exposed and the rate of exposure. Despite this prediction, little is known about how life‐history characteristics affect selection at the MHC. Here, we examined whether the strength of balancing selection on MHC class II genes in birds (as measured with nonsynonymous nucleotide substitutions, dN) was related to their social or migratory behavior, two life‐history characteristics correlated with pathogen exposure. Our comparative analysis indicated that the rate of nonsynonymous substitutions was higher in colonial and migratory species than solitary and resident species, suggesting that the strength of balancing selection increases with coloniality and migratory status. These patterns could be attributed to: (1) elevated transmission rates of pathogens in species that breed in dense aggregations, or (2) exposure to a more diverse fauna of pathogens and parasites in migratory species. Our study suggests that differences in social structure and basic ecological traits influence MHC diversity in natural vertebrate populations.     

Do habitat association models have any generality? Predicting skylark Alauda arvensis abundance in different regions of southern England

Much of conservation science is based upon determining the use by organisms of different resources. However, the field data used to construct habitat association models generally come from a small number of sites covering a fraction of the area of interest. It is important therefore to assess the generality of those models for species occurring over large geographical areas. In this paper we test the generality of models describing skylark Alauda arvensis abundance across farmland in southern England in relation to crop type, crop structure and field structure (i.e. height of surrounding boundaries). Skylarks responded to most predictors we measured in similar ways across three regions of differing farming practices (arable‐dominated, pasture‐dominated and a mixture of the two). Most of the regional differences in habitat associations could be related to differences in the speed of crop development. For example, the sowing of cereals in spring, a much lauded strategy to increase skylark populations, is likely to have less of an effect in regions where cereal development is slow than in regions where it is fast.
Most studies that explicitly test the performance of a model developed in one place elsewhere use presence/absence models. We adopt a more sensitive and novel approach by using counts. We found regression equations developed in one region performed poorly when tested as a direct predictor (i.e. a 1:1 relationship) on data from other regions. However, the skylark territories observed in any one region were positively correlated with the territory numbers predicted by models built using data from other regions, so models were good predictors of relative abundance.
The results suggest that, for this species at least, conservationists should have confidence when advocating management strategies based upon habitat‐association models and extrapolating their generality to other areas. However, our results warn against using regression equations developed in one place to make absolute quantitative predictions elsewhere. Decision‐makers should beware of using models in this way.