Apoptosis-independent Poor Morphology of Bovine Embryos Produced by Multiple Ovulation

In multiple ovulation and embryo transfer (MOET) programmes in cattle, a considerable number of morphologically poor-quality embryos continue to be produced; this is one of the limiting factors of the technique. Apoptosis has often been implicated in developmental arrest and fragmentation; these are regarded as poor traits of embryonic quality in mammalian pre-implantation embryos. In the present study, apoptosis was assessed in morphologically poor-quality embryos in comparison with good-quality embryos that were recovered from a MOET programme. Retarded embryos (two to 16 cell stage), morulae with severe fragmentation and morphologically good-quality morulae recovered from superstimulated cows at day 7 post-insemination were subjected to TdT-mediated dUTP nick-end labelling (TUNEL) and Hoechst staining. Cell nuclei that showed both TUNEL staining and apoptotic morphology were considered to be apoptotic. Apoptotic index (AI) was calculated as the percentage of apoptotic cells per embryo. Fifteen of 17 retarded embryos and 10 of 15 morphologically poor-quality morulae did not show signs of apoptosis. The mean AIs in the morphologically poor-quality embryos (two to 16 cell stage, 2.2%; poor morulae, 1.3%) were as low as that in the good-quality embryos (2.9%). These results suggest that another mode of developmental arrest and/or fragmentation that is independent of apoptosis occurs in morphologically poor-quality embryos recovered from MOET programmes.     

Rain forest recovery from dieback,Queensland, Australia

We present a detailed account of a dieback episode in tropical rain forest. The dieback episode took place from 1977 to 1989 within a 0.5 ha long-term demography plot monitored for stem growth and mortality from 1975 to 2005. In total 770 m² of rain forest was affected causing 13 trees >10 cm diameter at breast height (dbh) to die, and others to sicken. The dead trees came from four families, though 14 families were represented in the area. Trees of the family Elaeocarpaceae suffered significantly higher mortality. Larger trees were significantly more likely to die than small trees, but smaller trees were more likely to recover. Recruitment to >10 cm dbh size class after dieback was greater in areas that had been affected, and in 2005 stem density and basal area were higher than in 1977, before the dieback episode started. There were no significant trends in biodiversity change between affected and non-affected parts of the plot. Dieback may have dramatic effects at onset but over the medium term its impact appears to be less serious. Longer term monitoring will permit re-evaluation of this observation in the future.     

Biodiversity management approaches for stream–riparian areas: Perspectives for Pacific Northwest headwater forests,microclimates, and amphibians

Stream–riparian areas represent a nexus of biodiversity, with disproportionate numbers of species tied to and interacting within this key habitat. New research in Pacific Northwest headwater forests, especially the characterization of microclimates and amphibian distributions, is expanding our perspective of riparian zones, and suggests the need for alternative designs to manage stream–riparian zones and their adjacent uplands. High biodiversity in riparian areas can be attributed to cool moist conditions, high productivity and complex habitat. All 47 northwestern amphibian species have stream–riparian associations, with a third being obligate forms to general stream–riparian areas, and a quarter with life histories reliant on headwater landscapes in particular. Recent recognition that stream-breeding amphibians can disperse hundreds of meters into uplands implies that connectivity among neighboring drainages may be important to their population structures and dynamics. Microclimate studies substantiate a “stream effect” of cool moist conditions permeating upslope into warmer, drier forests. We review forest management approaches relative to headwater riparian areas in the U.S. Pacific Northwest, and we propose scenarios designed to retain all habitats used by amphibians with complex life histories. These include a mix of riparian and upslope management approaches to address the breeding, foraging, overwintering, and dispersal functions of these animals. We speculate that the stream microclimate effect can partly counterbalance edge effects imposed by upslope forest disturbances, hence appropriately sized and managed riparian buffers can protect suitable microclimates at streams and within riparian forests. We propose one approach that focuses habitat conservation in headwater areas – where present management allows extensive logging – on sensitive target species, such as tailed frogs and torrent salamanders that often occur patchily. Assuming both high patchiness and some concordance among the distribution of sensitive species, protecting areas with higher abundances of these animals could justify less protection of currently unoccupied or low-density habitats, where more intensive forest management for timber production could occur. Also, we outline an approach that protects juxtaposed headwater patches, retaining connectivity among sub-drainages using a 6th-field watershed spatial scale for assuring well-distributed protected areas across forested landscapes. However, research is needed to test this approach and to determine whether it is sufficient to buffer downstream water quality and habitat from impacts of headwater management. Offering too-sparse protection everywhere is likely insufficient to conserve headwater habitats and biodiversity, while our alternative targeted protection of selected headwaters does not bind the entire forest landscape into a biodiversity reserve.     

Evaporation from fetch-limited water bodies

An analytic model to calculate evaporation from fetch-limited water bodies is described. By modifying the surface boundary condition to an analytic solution to the advection-diffusion equation for specific humidity in the air flow over a water body, we are able to solve for the entire specific humidity field q (x, z) from a single measurement of humidity, surface temperature, and wind speed. Comparisons of model predictions with measurements from Rushy Billabong, a small turbid lake, over a 146 day period show that on average the model underestimates evaporation rates by 12%. We believe that the evaporation shortfall is due to the downwind advection of heat within the billabong when the billabong is highly stratified in temperature. When the thermal stratification is weak, the advection of heat within the water column is less important and the model is an accurate predictor of evaporation.     

Biofumigant Biomass,Nutrient Content,and Glucosinolate Response to Phosphorus

Information on biofumigant-green manure vegetative biomass, nutrient, and glucosinolate content sensitivity to phosphorus (P) is lacking for species used in potato and sugarbeet production. Therefore, available P effects on field-grown condiment yellow mustard (Sinapis alba, cv. IdaGold) and oilseed radish (Raphanus sativa, cv. Colonel) were evaluated (2001–03). Low soil P was generally more limiting to radish foliage P concentrations or uptake than to the mustard, suggesting inherent differences in their ability to access and accumulate P. While radish P and S concentrations increased with higher P, concentrations in mustard were either unaffected or reduced. Foliage P concentrations were more closely related to biomass of radish (r² = 0.46) than mustard (r² = 0.11). Mustard exceeded radish in biomass and S accumulation. Phosphorus effects on glucosinolates producing ionic or isothiocyanates were relatively insignificant. These biofumigants differ appreciably in their ability to access and accumulate P, but P effects on nutrient content or glucosinolates were minor.     

The influence of soil properties on the structure of bacterial and fungal communities across land-use types

Land-use change can have significant impacts on soil conditions and microbial communities are likely to respond to these changes. However, such responses are poorly characterized as few studies have examined how specific changes in edaphic characteristics do, or do not, influence the composition of soil bacterial and fungal communities across land-use types. Soil samples were collected from four replicated (n = 3) land-use types (hardwood and pine forests, cultivated and livestock pasture lands) in the southeastern US to assess the effects of land-use change on microbial community structure and distribution. We used quantitative PCR to estimate bacterial–fungal ratios and clone libraries targeting small-subunit rRNA genes to independently characterize the bacterial and fungal communities. Although some soil properties (soil texture and nutrient status) did significantly differ across land-use types, other edaphic factors (e.g., pH) did not vary consistently with land-use. Bacterial–fungal ratios were not significantly different across the land-uses and distinct land-use types did not necessarily harbor distinct soil fungal or bacterial communities. Rather, the composition of bacterial and fungal communities was most strongly correlated with specific soil properties. Soil pH was the best predictor of bacterial community composition across this landscape while fungal community composition was most closely associated with changes in soil nutrient status. Together these results suggest that specific changes in edaphic properties, not necessarily land-use type itself, may best predict shifts in microbial community composition across a given landscape. In addition, our results demonstrate the utility of using sequence-based approaches to concurrently analyze bacterial and fungal communities as such analyses provide detailed phylogenetic information on individual communities and permit the robust assessment of the biogeographical patterns exhibited by soil microbial communities.