GABA Control of GnRH Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol     

SPS Ghuman  DN Jones  S Prabhakar  RF Smith  H Dobson 《Reproduction in domestic animals》2008,43(5):531-541

The present study examines the involvement of GABA_{A or B} receptors in gonadotrophin‐releasing hormone (GnRH) release in vitro and determines whether oestradiol modulates γ‐aminobutyric acid (GABA)–GnRH interaction. Within 10 min after ewe killing, hypothalamic slices were dissected and placed in oxygenated Minimum Essential Media (MEM)‐α at 4°C; within 2 h, slices were singly perifused at 37°C with oxygenated MEM‐α (0.15 ml/min), with or without oestradiol (24 pg/ml). After 4 h equilibration, fractions were collected for 4 h interposed with a 10 min exposure to specific GABA_{A or B} receptor ligands (0.1–10 mm ). The GABA_{A or B} agonists (muscimol or baclofen) did not greatly influence GnRH release. However, GnRH increased (p < 0.05) after exposure to 10 mm GABA_{A or B} antagonists (bicuculline or CGP52432, respectively). The GABA_A antagonist stimulated greater sustained GnRH release (p < 0.05) in the absence of oestradiol than in its presence. The bioactivity of the released GnRH was studied using a hypothalamus‐pituitary sequential double‐chamber perifusion. Only after exposure of hypothalamic slices to the GABA_A antagonist, did the hypothalamic eluate stimulate luteinizing hormone release from pituitary fragments (p < 0.05) confirming that the GABA_A antagonist stimulated release of biologically active GnRH. In summary, GnRH release from the hypothalamus is predominantly under GABA_A receptor inhibitory control and this is attenuated in the presence of oestradiol.  相似文献   

Further evidence that zinc sulphate compromises the efficacy of dipping treatments using diazinon to control sheep lice (Bovicola ovis)     

ARB HIGGS  PW MORCOMBE  RA LOVE  GE YOUNG 《Australian veterinary journal》1998,76(1):44-49

Objective To compare the wettability and efficacy of diazinon dip wash made with and without the addition of zinc sulphate.
Design Field experiments using a shower and a plunge dip complemented by in-vitro wettability experiments.
Procedure A flock of infested sheep was divided into groups and treated in a shower dip with clear or cloudy dam water plus up to 1.5% zinc sulphate. Another infested line of sheep was treated using a plunge dip with nil or 1% zinc sulphate. In both experiments, wetting was assessed after dipping and louse counts were conducted for 9 months after treatment. Five in-vitro experiments compared the wettability of dip wash containing diazinon with up to 1.5% zinc sulphate added.
Results In the shower dipping experiment, live lice were found at 1 month after dipping in the cloudy water groups with 0.75%, 1.0% and 1.5% zinc sulphate and at 2 months in the 0.75% zinc sulphate group. No lice were found at subsequent inspections or at any time in the groups that were plunge dipped. Zinc sulphate decreased the amount of dip wash retained by wool staples in all in-vitro experiments (P < 0.05).
Conclusion Zinc sulphate should be considered as a risk factor that could cause failure to eradicate a lice infestation. The risk can be overcome by ensuring that all sheep are saturated at dipping and that the dip wash, and any holding tanks, are agitated throughout the dipping event.  相似文献   

Epidemiology of equine herpesvirus abortion: searching for clues to the future     

JR GILKERSON  DN LOVE  JM WHALLEY 《Australian veterinary journal》1998,76(10):675-676

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CORRECTION     

R. MALIK  DN LOVE  DI WIGNEY  P. MARTIN 《Australian veterinary journal》1998,76(6):398-398

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Identification of the vascular plants of Churchill,Manitoba, using a DNA barcode library     

Kuzmina  Maria L  Johnson  Karen L  Barron  Hannah R  Hebert  Paul DN 《BMC ecology》2012,12(1):1-11

Background

Using phylogenies in community ecology is now commonplace, but typically, studies assume and test for a single common phylogenetic signal for all species in a community, at a given scale. A possibility that remains little-explored is that species differing in demographic or ecological attributes, or facing different selective pressures, show different community phylogenetic patterns, even within the same communities. Here I compare community phylogenetic patterns for fire-killed and fire-resistant Banksia species in the fire-prone shrublands of southwest Australia.

Results

Using new Bayesian phylogenies of Banksia, together with ecological trait data and abundance data from 24 field sites, I find that fire regeneration mode influences the phylogenetic and phenotypic signal of species co-occurrence patterns. Fire-killed species (reseeders) show patterns of phylogenetic and phenotypic repulsion consistent with competition-driven niche differentiation, but there are no such patterns for fire-resistant species (resprouters). For pairs of species that differ in fire response, co-occurrence is mediated by environmental filtering based on similarity in edaphic preferences.

Conclusions

These results suggest that it may be simplistic to characterize an entire community by a single structuring process, such as competition or environmental filtering. For this reason, community analyses based on pairwise species co-occurrence patterns may be more informative than those based on whole-community structure metrics.  相似文献   

Inconsistent efficacy of water-soluble amphotericin B for the treatment of Macrorhabdus ornithogaster in a budgerigar (Melopsittacus undulatus) aviary     

HR Baron  BC Stevenson  DN Phalen 《Australian veterinary journal》2020,98(7):333-337

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Early abortion of gilts as a way of synchronising oestrus and improving litter size     

RJ LOVE  RG GREY 《Australian veterinary journal》1993,70(12):452-452

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Principles for the use of macrocyclic lactones to minimise selection for resistance     

RJ DOBSON  RB BESIER  EH BARNES  SCJ LOVE  A VIZARD  K BELL  LF Le  JAMBRE 《Australian veterinary journal》2001,79(11):756-761

OBJECTIVE: To provide principles for the appropriate use of avermectin/milbemycin or macrocyclic lactone (ML) anthelmintics in sheep, to ensure effective worm control and to minimise selection for ML resistance. STRATEGY: The principles were based on an assessment of the information currently available. The MLs were categorised into three groups (ivermectin [IVM], abamectin [ABA] and moxidectin [MOX]) based on structural differences, persistence and efficacy against ML resistant strains. The reported order of activity or efficacy against ML resistant worm strains was IVM相似文献   

Feline calicivirus: a need for vaccine modification?     

C. BAULCH-BROWN  DN LOVE  J. MEANGER 《Australian veterinary journal》1997,75(3):209-213

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Differential expression of ISG 15 mRNA in peripheral blood mononuclear cells of nulliparous and multiparous pregnant versus non‐pregnant Bos indicus cattle          下载免费PDF全文

NP Soumya  DN Das  S Jeyakumar  S Mondal  A Mor  UT Mundhe 《Reproduction in domestic animals》2017,52(1):97-106

Embryonic mortality is found to be the main source of reproductive wastage in domestic ruminants. Many genes are involved in the growth and development of the embryo, and the interferon‐stimulated gene 15 (ISG 15) is one of the major gene stimulated by interferon tau, the maternal recognition of pregnancy signal in ruminants. In this study, both genomic and cDNA sequences of ISG 15 from Bos indicus (Deoni breed) were amplified and characterized. The genomic sequence of Deoni ISG 15 exhibited 99% identity with Bos taurus and 97% identity with that of Bos mutus and Bubalus bubalis. Moreover qRT‐PCR analysis revealed constitutive expression of the ISG 15 mRNA in peripheral blood mononuclear cells of Deoni heifers and multiparous cows during early pregnancy. Fourteen Deoni heifers and fifteen multiparous Deoni cows were synchronized for timed AI by CIDR‐Ovsynch protocol, and six animals were kept as cyclic control in each group. Blood samples were collected on days 7, 14, 16, 18, 21, 30 and 45 from the day of AI. Pregnancy was confirmed by plasma progesterone level through ELISA. A significantly higher expression of ISG 15 mRNA was found on day 16 (p < .05) and day 18 (p < .05) of pregnancy in nulliparous heifers. Although in multiparous Deoni cows ISG 15 expression was greater in pregnant cows, difference was statistically non‐significant. The result of this study indicates that ISG 15 gene expression is upregulated during 16–18 days of pregnancy and could be used as an early pregnancy marker in dairy cows especially in heifers.  相似文献