Bee communities (Hymenoptera: Apoidea) of small Iowa hill prairies are as diverse and rich as those of large prairie preserves

Natural small, xeric hill prairies in forested landscapes throughout the Midwest United States often contain high diversity and unique species of some organisms because of their unusual landscape context and microclimate. We measured the diversity, richness, and abundance of the bee communities of five hill prairies located in northeastern Iowa and we compared these to values for large prairie preserves in northwestern Iowa, using a Monte Carlo resampling approach to standardize sampling effort between habitat types. We also measured the diversity and richness of the flowering forb communities at the hill prairies and we quantified percentage of the landscape at a 1 km radius in different landscape elements. Bee diversity at the five hill prairies spanned the range of diversity values for large prairies preserves, so although the hill prairies are small (<5 ha), their bee communities are not uniformly depauparate compared to larger western prairie preserves. Bee diversity was significantly related to flowering forb diversity, and may have been influenced by landscape features within 1 km—particularly the percentage of agricultural row crops and open water, which may negatively affect bee diversity at the sites. Iowa’s hill prairie bee communities were largely composed of widespread eastern species, although about 10% of the bee species have more northern or western ranges and appear to be taking advantage of the region’s unique habitat features. Given the dependence of the bee communities on the plant diversity of the sites, management of the plant community to maintain its diversity will also likely benefit bee diversity.     

Corticotropin-releasing factor receptor type 2-deficient mice display impaired coping behaviors during stress

Two cognate receptors (CRF(1) and CRF(2)) mediate the actions of the stress-regulatory corticotropin-releasing factor (CRF) family of peptides. Defining the respective roles of these receptors in the central nervous system is critical in understanding stress neural circuitry and the development of psychiatric disorders. Here, we examined the role of CRF(2) in several paradigms that assess coping responses to stress. We report that CRF(2) knockout mice responded to a novel setting with increased aggressive behavior toward a bulbectomized conspecific male and show increased immobility during acute swim stress compared with wild-type mice. In addition, CRF(2)-deficient mice exhibited impaired adaptation to isolation stress as evinced by prolonged hypophagia and associated weight loss. Collectively, these results point toward a role for CRF(2) pathways in neural circuits that subserve stress-coping behaviors.     

The dynamics of imprinted X inactivation during preimplantation development in mice

In the mouse, there are two forms of X chromosome inactivation (XCI), random XCI in the fetus and imprinted paternal XCI, which is limited to the extraembryonic tissues. While the mechanism of random XCI has been studied extensively using the in vitro XX ES cell differentiation system, imprinted XCI during early embryonic development has been less well characterized. Recent studies of early embryos have reported unexpected findings for the paternal X chromosome (Xp). Imprinted XCI may not be linked to meiotic silencing in the male germ line but rather to the imprinted status of the Xist gene. Furthermore, the Xp becomes inactivated in all cells of cleavage-stage embryos and then reactivated in the cells of the inner cell mass (ICM) that form the epiblast, where random XCI ensues.     

A review of Australian classical biological control of weeds programs and research activities over the past 12 years

Considerable progress has been made towards the successful classical biological control of many of Australia’s exotic weeds over the past decade. Some 43 new arthropod or pathogen agents were released in 19 projects. Effective biological control was achieved in several projects with the outstanding successes being the control of rubber vine, Cryptostegia grandiflora, and bridal creeper, Asparagus asparagoides. Significant developments also occurred in target prioritization, procedures for target and agent approval, funding, infrastructure and cooperation between agencies. Scientific developments included greater emphasis on climate matching, plant and agent phylogeny, molecular diagnostics, agent prioritization and agent evaluation.     

Positively charged residues, the helical conformation and the structural flexibility of the leader sequence of pALDH are important for recognition by hTom20

Tom20, a mitochondrial outer membrane receptor necessary for protein translocation, was found to interact specifically with mitochondrial preproteins. The interaction of proteins containing an N-terminal matrix targeting signal was enhanced in an hydrophobic environment and the dependence of this interaction on the alpha helical conformation of the presequence was postulated. In order to test this hypothesis and to gain insights about the features of a matrix targeting signal necessary to be recognized by the receptor machinery including Tom20, the interaction of pALDH and signal sequence mutants to Tom20 in the absence and presence of a hydrophobic environment was investigated. Here we present evidence to show that in a hydrophobic environment the interaction between Tom20 and the leader sequence is strongly dependent on the positive charges within the signal sequence as well as on the flexibility of this signal.     

Xist yeast artificial chromosome transgenes function as X-inactivation centers only in multicopy arrays and not as single copies

X-chromosome inactivation in female mammals is controlled by the X-inactivation center (Xic). This locus is required for inactivation in cis and is thought to be involved in the counting process which ensures that only a single X chromosome remains active per diploid cell. The Xist gene maps to the Xic region and has been shown to be essential for inactivation in cis. Transgenesis represents a stringent test for defining the minimal region that can carry out the functions attributed to the Xic. Although YAC and cosmid Xist-containing transgenes have previously been reported to be capable of cis inactivation and counting, the transgenes were all present as multicopy arrays and it was unclear to what extent individual copies are functional. Using two different yeast artificial chromosomes (YACs), we have found that single-copy transgenes, unlike multicopy arrays, can induce neither inactivation in cis nor counting. These results demonstrate that despite their large size and the presence of Xist, the YACs that we have tested lack sequences critical for autonomous function with respect to X inactivation.     

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. I. Soil-surface-active invertebrates

The effects of herbicide management of genetically modified herbicide-tolerant (GMHT) beet, maize and spring oilseed rape on the abundance and diversity of soil-surface-active invertebrates were assessed. Most effects did not differ between years, environmental zones or initial seedbanks or between sugar and fodder beet. This suggests that the results may be treated as generally applicable to agricultural situations throughout the UK for these crops. The direction of the effects was evenly balanced between increases and decreases in counts in the GMHT compared with the conventional treatment. Most effects involving a greater capture in the GMHT treatments occurred in maize, whereas most effects involving a smaller capture were in beet and spring oilseed rape. Differences between GMHT and conventional crop herbicide management had a significant effect on the capture of most surface-active invertebrate species and higher taxa tested in at least one crop, and these differences reflected the phenology and ecology of the invertebrates. Counts of carabids that feed on weed seeds were smaller in GMHT beet and spring oilseed rape but larger in GMHT maize. In contrast, collembolan detritivore counts were significantly larger under GMHT crop management.     

On the rationale and interpretation of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

Farmland biodiversity and food webs were compared in conventional and genetically modified herbicide-tolerant (GMHT) crops of beet (Beta vulgaris L.), maize (Zea mays L.) and both spring and winter oilseed rape (Brassica napus L.). GMHT and conventional varieties were sown in a split-field experimental design, at 60-70 sites for each crop, spread over three starting years beginning in 2000. This paper provides a background to the study and the rationale for its design and interpretation. It shows how data on environment, field management and the biota are used to assess the current state of the ecosystem, to define the typical arable field and to devise criteria for selecting, sampling and auditing experimental sites in the Farm Scale Evaluations. The main functional and taxonomic groups in the habitat are ranked according to their likely sensitivity to GMHT cropping, and the most responsive target organisms are defined. The value of the seedbank as a baseline and as an indicator of historical trends is proposed. Evidence from experiments during the twentieth century is analysed to show that large changes in field management have affected sensitive groups in the biota by ca. 50% during a year or short run of years--a figure against which to assess any positive or negative effects of GMHT cropping. The analysis leads to a summary of factors that were, and were not, examined in the first 3 years of the study and points to where modelling can be used to extrapolate the effects to the landscape and the agricultural region.