Vascular Endothelial (VEGF) and Epithelial Growth Factor (EGF) as Well as Platelet‐Activating Factor (PAF) and Receptors are Expressed in the Early Pregnant Canine Uterus

The aim of this study was to investigate the course of expression of platelet‐activating factor (PAF), PAF‐receptor (PAF‐R), epidermal growth factor (EGF), EGF‐R, vascular endothelial growth factor (VEGF), VEGF‐R1 and VEGF‐R2 in uterine tissue during canine pregnancy. For this purpose, 20 bitches were ovariohysterectomized at days 10–12 (n = 10), 18–25 (n = 5) and 28–45 (n = 5) days after mating, respectively. The pre‐implantation group was proven pregnant by embryo flushing of the uterus after the operation, the others by sonography. Five embryo negative, that is, non‐pregnant, bitches in diestrus (day 10–12) served as controls. Tissue samples from the uterus (placentation sites and horn width, respectively) were excised and snap‐frozen in liquid nitrogen after embedding in Tissue Tec^®. Extraction of mRNA for RT‐PCR was performed with Tri‐Reagent. In the embryos, mRNA from all factors except VEGF was detected. In the course of pregnancy, significantly higher expression of PAF and PAFR as well as VEGF and VEGFR2 during the pre‐implantation stage than in all other stages and a strong upregulation of EGF during implantation were characteristic. The course of EGF was in diametrical opposition to the course of the receptor. These results point towards an increased demand for VEGF, EGF and PAF during the earliest stages of canine pregnancy.     

Dehydrogenation: A previously unreported pathway of lindane metabolism in mammals

This study presents evidence for the dehydrogenation of lindane by a hepatic microsomal mixed-function oxidase system. Preliminary investigation established that the incubation of lindane with rat liver homogenates produces a chlorinated, nonpolar compound identified as hexachlorocyclohexene. Differential centrifugation resulted in the sedimentation of most of the dehydrogenase activity in the microsomal fraction. Optimum in vitro assay conditions were established and it was found that the dehydrogenase system required molecular oxygen and reduced pyridine nucleotide coenzyme for maximum activity. Inhibition by SKF 525-A and CO suggested that the enzyme was cytochrome P-450 dependent. Lack of inhibition by cyanide indicated that the cytochrome b₅ desaturase system was probably not involved. Pretreatment of rats with DDT, which stimulates lindane metabolism, also induced significantly higher dehydrogenase activity. Both the in vivo and in vitro metabolism of hexachlorocyclohexene produced previously identified lindane metabolites. The existence of a cytochrome P-450 dependent mixed-function oxidase which catalyzes the dehydrogenation of lindane has not previously been reported and may be of importance in the metabolism of other xenobiotics.     

In vitro differentiation of bovine bone marrow‐derived mesenchymal stem cells into male germ cells by exposure to exogenous bioactive factors

Mesenchymal stem cells (MSC) are multipotent progenitor cells defined by their ability to self‐renew and give rise to differentiated progeny. Previous studies have reported that MSC may be induced in vitro to develop into different types of specialized cells including male gametes. In vitro gamete derivation technology has potential applications as an alternative method for dissemination of elite animal genetics, production of transgenic animals and conservation of endangered species. This study aimed at investigating the in vitro effect of BMP4, TGFβ1 and RA on the potential for germ cell (GC) differentiation of bovine foetal MSC (bfMSC) derived from bone marrow (BM). The effect of BMP4, TGFβ1 and RA was analysed on the expression of pluripotent, GC and male GC markers on bfMSC during a 21‐day culture period. bfMSC cultured under in vitro conditions expressed OCT4, NANOG and DAZL, but lacked expression of mRNA of VASA, STELLA, FRAGILIS, STRA8 and PIWIL2. Treatment with exogenous BMP4 and TGFβ1 induced a transient increase (p < .05) in DAZL and NANOG mRNA levels, respectively. However, exposure to RA was more effective in increasing (p < .05) expression of DAZL and regulating expression of OCT4 and mRNA levels of NANOG. These data suggest that bfMSC may possess potential for early GC differentiation, where OCT4, NANOG and specially DAZL may play significant roles in controlling progression along the GC lineage.     

The increasing scarcity of red oaks in Mississippi River floodplain forests: Influence of the residual overstory

Red oaks – cherrybark oak (Quercus pagoda Raf.), willow oak (Quercus phellos L.), water oak (Quercus nigra L.), and Nuttall oak (Quercus texana Buckley; aka: Quercus nuttallii Palmer) – are not regrowing in Mississippi Delta river floodplain forests in the southeastern United States in sufficient numbers to sustain the former species composition and timber and wildlife values. Even if vigorous red oak reproduction becomes established, partial harvesting that does not remove the taller trees will suppress understory red oak height growth more than it will suppress height growth of such other species as sugarberry (Celtis laevigata Willd.), American elm (Ulmus americana L.), cedar elm (Ulmus crassifolia Nutt.), swamp dogwood (Cornus foemina Mill.), green ash (Fraxinus pennsylvanica Marshall), and sweetgum (Liquidambar styraciflua L.). Consequently, the red oaks in these partially harvested stands become increasingly suppressed and probably die; and there is a shift in species composition to the other species. In addition to ensuring vigorous oak reproduction, silvicultural clearcutting or rapid removal of the residual trees following shelterwood or seed tree harvesting to provide full sunlight is needed to ensure red oaks become a dominant part of these future river floodplain stands.     

Use of a 0.25 per cent fipronil pump spray formulation to treat canine cheyletiellosis

Two outbreaks of cheyietieilosis are described. In one of the outbreaks, a human member of the household was also affected. A 0.25 per cent flpronil pump spray formulation was applied to the affected and in-contact animals. A permethrin spray was used in an attempt to eliminate environmental contamination. One month later, the affected animals were reexamined. No evidence of Cheyletiella mites could be found. A second application of fipronil was undertaken. No further outbreaks were reported during an eight month follow-up.     

Laboratory study of the effects of two nitrification inhibitors on greenhouse gas emissions from a slurry-treated arable soil: impact of diurnal temperature cycle

An automated laboratory soil incubation system enabled the effects on gaseous emissions from a soil to be quantified accurately, when amended with slurry plus a nitrification inhibitor: dicyandiamide (DCD), or 3,4-dimethylpyrazole phosphate (DMPP). Nitrification inhibitors applied with slurry under simulated Portuguese conditions were very efficient in reducing N₂O emission, and did not increase CH₄ emissions significantly, when the soil was predominantly aerobic. The inhibitors were also indirectly effective in reducing N₂O emissions due to denitrification during a subsequent anaerobic phase. All gaseous emissions followed strong diurnal patterns that were positively correlated with soil temperature and obeyed a Q₁₀=2 relationship. The widespread use of DCD and DMPP inhibitors with slurry applied to Portuguese soils could have the potential to reduce N₂O emissions from this source by ten- to 20-fold.     

Recovery of benthic invertebrate communities in silver bow creek,montana, following improved metal mine wastewater treatment

Silver Bow Creek, a tributary of the Clark Fork River in southwest Montana, has been affected by metal mining and domestic wastes for over 100 yr. The invertebrate community was monitored at five stations from 1972 through 1983 to determine both the longitudinal and temporal patterns of recovery following major improvements in mine wastewater treatment. This treatment dramatically reduced metal concentrations in the mine discharge. Despite markedly improved water quality, no invertebrates were collected in Silver Bow Creek until 1975, when small numbers of invertebrates (primarily chironomids) were collected at the furthest downstream stations. A few invertebrates (<75 m^?2) were collected for the first time at Stations 1 and 2 in 1981, although the lower stations still had much greater densities (> 1600 m^?2). The earliest colonizers at each station were chironomids, empidids, and oligochaetes. In 1982, 10 yr after initiation of improved water quality, aquatic insect populations were over 1800 m^?2 at all five stations. Populations dropped in 1983, but upper and lower stations had comparable densities suggesting that the stream is responding to a common stress such as high snowmelt runoff. The relatively long recovery time is partially attributed to the lack of an undisturbed headwater source of colonizers.