Linking winter and summer events in a migratory bird by using stable-carbon isotopes   总被引：1，自引：0，他引：1  

PP Marra  KA Hobson  RT Holmes 《Science (New York, N.Y.)》1998,282(5395):1884-1886

For migratory birds, early arrival and physical condition on the breeding grounds are important determinants of reproductive success and fitness. Differences in arrival times often exceed a month, and later arriving individuals are often in poorer condition. Habitat-specific isotopic signatures indicate that the quality of winter habitats occupied by American redstarts (Setophaga ruticilla) determines their physical condition and spring departure dates, which in turn result in variable arrival schedules and condition on temperate breeding grounds. These findings link events in tropical winter grounds with those in temperate breeding areas for a migratory songbird and provide evidence that winter habitats may be limiting.  相似文献   

Adverse reaction to procaine penicillin G in horses     

IL NIELSEN  KA JACOBS  PJ HUNTINGTON†  CB CHAPMAN‡  KC LLOYD§ 《Australian veterinary journal》1988,65(6):181-185

Adverse reactions to intramuscular injections of procaine penicillin G are reported in 11 horses, five of which died. The clinical findings are presented and suggest central nervous involvement in most cases. Post mortem findings in one horse were consistent with anaphylaxis whereas in other cases the clinical findings, duration of treatment, speed of onset and subsequent completion of treatment supports diagnosis of an acute procaine toxicity syndrome.  相似文献   

Ecology of verotoxigenic Escherichia coli     

KA BETTELHEIM 《Australian veterinary journal》1997,75(12):912-912

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A pulmonary adenoma in an Australian sheep     

PT HOOPER  KA ELLARD 《Australian veterinary journal》1995,72(12):477-477

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Sarcoptic mange in wombats   总被引：1，自引：0，他引：1  

LF SKERRATT  RW MARTIN  KA HANDASYDE 《Australian veterinary journal》1998,76(6):408-410

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Tumour angiogenesis,anti‐angiogenic therapy and chemotherapeutic resistance          下载免费PDF全文

KA Mander  JW Finnie 《Australian veterinary journal》2018,96(10):371-378

In order for a tumour to continue to grow and disseminate, it must acquire a new blood supply. Neovascularisation can be enacted by a number of different mechanisms. This dependence of tumour progression on an augmented vascular supply has been exploited by the development of anti‐angiogenic drugs, which are designed to inhibit new blood vessel formation or disrupt existing tumour‐associated vasculature, both leading to ischaemic–hypoxic tumour cell death. However, the clinical benefits of these therapeutic approaches are frequently variable and often transient, the neoplasm sometimes being able to use other neovascularisation mechanisms to maintain its blood supply and thus evade the current anti‐angiogenic therapy. Tumours may also develop a more malignant phenotype following this treatment. Clinical outcomes may be improved by simultaneously inhibiting different angiogenic pathways, abetted by more effective drug delivery regimens such as metronomic chemotherapy and the concurrent use of other antitumour modalities.  相似文献   

The impact of bisphenol S on bovine granulosa and theca cells          下载免费PDF全文

KA Campen  M Lavallee  CMH Combelles 《Reproduction in domestic animals》2018,53(2):450-457

Bisphenol S (BPS) is an endocrine‐disrupting chemical with multiple potential mechanisms of action, including as an oestrogen receptor agonist. BPS is increasingly used in plastics and thermal receipts as a substitute for bisphenol A, which has been phased out due to concerns about human health implications. The ability of BPS to alter female reproductive function in mammals has not been widely studied, despite the importance of normal hormone signalling for female reproduction. The aim of this study was to investigate how BPS (in a wide range of doses, including very low doses) affects granulosa cell and theca cell steroid hormone production and cell viability in the bovine. Granulosa cell oestradiol production was stimulated when cells were exposed to 100 μM BPS under basal conditions, but there was no effect of BPS when cells were stimulated with follicle‐stimulating hormone (FSH). Additionally, there was no effect of BPS on granulosa cell progesterone production or cell viability under basal or FSH‐stimulated conditions. BPS did not affect theca cell androstenedione or progesterone production, or theca cell viability under basal or luteinizing hormone‐stimulated conditions. This study suggests for the first time that BPS may alter oestradiol production by bovine granulosa cells, albeit at a concentration that is unlikely to be physiologically relevant. Further studies are needed to determine the effects of BPS on the bovine oocyte and on other functions of follicular cells.  相似文献   

南疆灌区冬小麦/夏玉米改良模式增产潜力与机理分析     

章建新  赵明  图尔贡  卡地尔亚 《干旱地区农业研究》2013,31(6):15-21

田间试验系统地比较了新冬20/沈玉2002不同套种模式（“522模式”与“952模式”）及“521模式”下保麦10号/蠡玉35、保麦10号/登海3672、新冬20/蠡玉35的产量、叶面积指数、光合势及干物质积累等性状的差异。结果表明,“522模式”新冬20/沈玉2002周年产量（17 838.2 kg·hm^-2）较“952模式”(16 550.9 kg·hm^-2)增产7.8%,其中,冬小麦增产18.4%。“521模式”保麦10号/蠡玉35、保麦10号/登海3672、新冬20/蠡玉35周年产量为19 905.0～20 751.0 kg·hm^-2,其中,冬小麦产量为9 740～10 275 kg·hm^-2、夏玉米产量为9 630～10 211.0 kg·hm^-2;冬小麦孕穗期和开花期叶面积指数分别为6.0、5.0左右,返青至成熟的总光合势290.2～324.3×10⁴·m²·d·hm^-2;夏玉米生育期111 d,大喇叭口期至吐丝后20 d的叶面积指数均保持在4左右,生育期间总光合势233.1～257.5×10⁴·m²·d·hm^-2,冬小麦和玉米总光合势为523.3～581.8×10⁴·m²·d·hm^-2;总干物质量38 569.1～40 487.0 kg·hm^-2;冬小麦产量的边际效应为85.7%～112.9%。“521模式”比“952模式”大幅度增产,是小麦行数和边行数及边际产量增大的结果,并将夏玉米播期提至麦收前15 d左右,延长玉米生育期（达110 d左右）,优化株行配置使玉米增产显著,实现全年超高产。“521模式”同时充分利用了冬小麦边际补偿效应和玉米时间补偿效应,较“952模式”易获得周年超高产。并对超高产栽培技术进行了讨论。  相似文献   

Preliminary Studies on Cryopreservation of Common Tench (Tinca tinca) Embryos (Work in Progress)     

KA El-Battawy  O Linhart 《Reproduction in domestic animals》2009,44(4):718-723

Vitrification could provide a promising tool for the cryopreservation of fish embryos. However, to achieve cryopreservation using vitrification, chilling sensitivity and cryoprotectants toxicity were determined using tench embryos at four developmental stages (11, 17, 23 and 29 h). Embryos treated with alcalase (2 ml/998 ml, 2 min at 22°C) were exposed to chilling with/without warming. Other embryos were exposed to methanol and glycerol at the concentration of 10% and 20% for periods of 20 min. At last, embryos were incubated at special incubator cages where hatching rates were counted. Regarding chilling sensitivity and exposure to chilling followed by warming, the hatching rates of embryos decreased significantly (p < 0.001) after exposure to 0°C at all developmental stages except the 29-h stage compared with the controls. The embryo stage most sensitive to chilling was 11-h stage. The 29-h stage exhibited the least sensitivity to low temperature while 17-h and 23-h stages were intermediate in their sensitivity to chilling. The toxicity of methanol increased significantly (p < 0.001) with developmental stage for 11, 17 and 23-h stages. The highest hatching rates of tench embryos were obtained with 29-h embryos using various concentrations of methanol. The hatching rates of tench embryos exposed to glycerol concentrations were approximately similar to those embryos exposed to methanol concentrations except for 11-h embryos that showed no hatching. Unfortunately, we could not obtain living embryos in any of the conditions examined after vitrification. In conclusion, it was quite difficult to vitrify the tench embryos during this study using various vitrifying solutions and the method reported by Chen & Tian (2005) and further studies are needed to achieve successful cryopreservation.  相似文献   

Observed and modelled distributions of channel and gully heads—with examples from SE Spain and Belgium     

M. J. Kirkby  L. J. Bull  J. Poesen  J. Nachtergaele  L. Vandekerckhove 《CATENA》2003,50(2-4):415-434

In soil erosion by overland flow, sediment discharge is driven by discharge and gradient against the resistance of the soil and vegetation. The form of the relationship, which is taken as a sum of power law terms, may then be inferred from several data sources: (1) ephemeral gully head location, (2) permanent channel head location, (3) slope profile form, (4) consistency with evolutionary models and (5) erosion plot data. The paper focuses on (1) to (4), in order to understand how far these data constrain the form of the dependence on discharge and gradient. Field data from mapping a set of ephemeral gully heads after storms show a weak inverse relationship between channel head gradient and catchment area, which flattens towards an upper threshold gradient of about 25%. These relationships are compared with those theoretically obtained for a range of sediment transport laws which have been previously used, and which are analysed to forecast both overall slope profile form and the location of stream heads. The theory predicts that the location of ephemeral gully heads produced in a single storm will differ from the long-term average stream head location. There is a fairly good relationship between theoretical and observed locations, associated with the form of the sediment transport law. For a single event, the location depends on storm magnitude which cannot be well defined from the data sets, creating a spread of data with an envelope curve defined for the largest events. The empirically acceptable sediment transport equations have also been used to analyse families of slope profiles in a small area, and used within a landscape evolution model to generate landscapes which are compatible with those observed in the field, and provide confirmation of the long-term viability of the expressions obtained to forecast the direction, style and rates of landscape evolution in response to land use or climate drivers.  相似文献