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D.H. Eccles 《African Zoology》2013,48(3):257-263
Barbus aeneus is one of the most important fishes in the P.K. le Roux Dam, being found over the whole surface and on the bottom down to the thermocline or to 30 m. It is omnivorous, but its diet varies with size. Below a length of 100 mm it feeds mainly on zoobenthos, from 101-300 mm zooplankton is the principal food but in larger fish vegetable food becomes increasingly important. B. aeneus is the principal vertebrate consumer of zooplankton in the dam, but takes only the larger species which are located visually. The quantity of zooplankton in the diet was related, not to its density, but to light and transparency which were the most important non-seasonal influences on the diet. Seasonal effects were marked, zooplankton being most important during summer and autumn while empty stomachs were most frequent in winter and spring. In rivers, larger B. aeneus feed on bigger invertebrates and on vegetable material. These are limited in the P.K. le Roux Dam and sub-adults experience high mortality once they can no longer feed efficiently on zooplankton. The size at which this occurs is determined largely by turbidity, and this should be taken into consideration in formulating management policies. 相似文献
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Callosobruchus maculatus (F.), a major pest of grain legumes, causes considerable losses worldwide. C. maculatus management relies on synthetic insecticides with their adverse environmental and health concerns. The current study investigated the use of Artocarpus altilis (breadfruit) extracts on contact and fumigant toxicity, repellency and oviposition deterrency of C. maculatus as a management strategy. Fumigant mortality (LC50) of the dry inflorescence extract of A. altilis was 126.65 µL L?1 air at 53.4 h. Fruit extract gave 73.3% repellency at 1000 ppm after 24 h. Percent repellency was dose and time dependent. Green inflorescence extract of A. altilis reduced egg laying with 50% oviposition occurring after 37.78 h at 1000 ppm. We conclude that extracts of leaf, fruit, green and dried inflorescence of A. altilis displayed contact mortality, repellency, deterred oviposition and had fumigant activity toward C. maculatus. 相似文献
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Johnstone AC Davidson BI Roe AR Eccles MR Jolly RD 《New Zealand veterinary journal》2005,53(5):307-314
AIM: To describe the pathology and inheritance of a congenital polycystic kidney disease (PKD) of sheep. METHODS: Mode of inheritance of PKD was investigated by evaluation of results of the disorder from planned matings in two consecutive years within subsets of a flock that had a high prevalence of PKD in lambs. Gross pathological and histopathological studies were based on tissues derived from this study. Haematoxylin and eosin (H&E)-stained paraffin sections of kidney, liver, extrahepatic biliary and pancreatic ducts, pancreas and epididymis were used to describe the lesions. RESULTS: Twenty-five lambs affected by PKD, of both sexes, were born, numbers in accord with those expected for an autosomal recessive disorder in the population studied. In all cases for which tissues were available, the renal, bile ductal (intrahepatic and extrahepatic), pancreatic and epididymal tissues had widespread dysplastic changes and associated cyst formation. CONCLUSIONS: The findings of renal cysts in conjunction with cysts in other organs are unifying features in many of the human and animal forms of PKD and suggest a related pathogenic and genetic base consistent with an autosomal recessive disorder. 相似文献
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AC Johnstone BI Davidson AR Roe MR Eccles RD Jolly 《New Zealand veterinary journal》2013,61(5):307-314
AIM: To describe the pathology and inheritance of a congenital polycystic kidney disease (PKD) of sheep. METHODS: Mode of inheritance of PKD was investigated by evaluation of results of the disorder from planned matings in two consecutive years within subsets of a flock that had a high prevalence of PKD in lambs. Gross pathological and histopath- ological studies were based on tissues derived from this study. Haematoxylin and eosin (H&E)-stained paraffin sections of kidney, liver, extrahepatic biliary and pancreatic ducts, pancreas and epididymis were used to describe the lesions. RESULTS: Twenty-five lambs affected by PKD, of both sexes, were born, numbers in accord with those expected for an autosomal recessive disorder in the population studied. In all cases for which tissues were available, the renal, bile ductal (intrahepatic and extrahepatic), pancreatic and epididymal tissues had widespread dysplastic changes and associated cyst formation. CONCLUSIONS: The findings of renal cysts in conjunction with cysts in other organs are unifying features in many of the human and animal forms of PKD and suggest a related pathogenic and genetic base consistent with an autosomal recessive disorder. 相似文献
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D.H. Eccles 《African Zoology》2013,48(1):68-72
The effect of temperature on the rate of gut evacuation in Barbus aeneus was investigated in two ways. In the first, juvenile fish, kept under conditions of constant temperature, were fed marked food items and the time elapsing until these appeared in the faeces was noted. In the second, fish of a range of sizes were caught in the P.K. le Roux dam and immediately placed in cages in the dam to prevent their access to food. Groups of fish were sacrificed at intervals and the contents of standardized gut sections weighed. The field experiment was carried out in summer and in winter. The laboratory experiment yielded the relationship: P = 6270 × t-2,11 where P is the passage time in hours and T is the temperature in °C. This gives passage times of the order of 8 h at 25°C and 39 h at 11,5°C. The field experiment indicated that there was an exponential relationship between degree of fullness and rate of evacuation, and that complete evacuation required about 24 h in summer, but more than 5 days in winter. 相似文献
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- 1. In Australia, the carp Cyprinus carpio L. is regarded as a threat to the native fish and the aquatic environment. In recent years, Botany Wetlands, a significant coastal wetland in the Sydney region, has been invaded by the undesirable cyprinids, carp and goldfish (Carrasius auratus L.).
- 2. In 1996 a cyprinid removal programme commenced at Botany Wetlands with the objective of managing the invasive species, increasing fish diversity, reducing cyanobacterial blooms and hence enhancing the aquatic habitat. Using electrofishing and gill netting, 4073 carp and 261 goldfish, amounting to 10 117 kg of cyprinid biomass were removed between 1996 and 2004. The captured carp ranged from 60 to 835 mm. Males matured before females. Carp between 350 and 680 mm in length grew at the rate of 1.66±0.38 g day?1.
- 3. The success of the programme was monitored by assessing four indicators related to carp populations and two related to habitat. The former included the pattern of length–frequency distribution, mean weight per size class, condition factor (CF) and the catch per unit effort (CPUE), and the latter the Secchi disc transparency and cyanobacterial counts. After 8 yr of removal, the plots of carp length–frequency distribution flattened, CF decreased from 2.86 to 1.82 and CPUE decreased from 97 kg day?1 to 50 kg day?1. A 10‐fold decrease occurred in cyanobacterial counts and the Secchi disc transparency increased by 20%. More than 20 000 fingerlings of native Australian bass Macquaria novemaculeata (S.) have been introduced to the wetlands, increasing the potential for juvenile carp predation and biodiversity.
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Ineson J Stayner C Hazlett J Slobbe L Robson E Legge M Eccles MR 《The Journal of reproduction and development》2012,58(4):490-500
Genomic imprinting confers allele-specific expression in less than 1% of genes, in a parent-of-origin specific fashion. In humans and mice the Peg1/Mest gene (Mest) is maternally repressed, and paternally expressed. Mest is expressed in embryogenic mesoderm-derived tissues and in adult brain, and paternal mutations in Mest lead to growth retardation and defective maternal behaviour. Despite our current understanding of mechanisms associated with the establishment of imprinting of Mest and other imprinted genes, it is unclear to what extent Mest imprinting needs to be maintained in adult tissues. Aberrations of imprinting are known to occur in certain rare syndromes, and involve either inherited mutations, or constitutive epigenetic alterations occurring soon after fertilization. Imprinting abnormalities may also occur in the aging somatic tissues of adult individuals. Here we report an occurrence of post-embryonic somatic variability of Mest allelic expression in a colony of mice where heterozygotes at the imprinted Mest locus for a mutation inherited from the father spontaneously expressed the normally silenced allele from the mother. In addition, a newly acquired ability to overcome the deficit in maternal reproductive behaviour had occurred in the mutant mice, but this appeared not to be directly linked to the Mest mutation. Our results suggest that at least one allele of Mest expression is required in the somatic tissues of adult individuals and that under certain conditions (such as in the presence of a Mest insertional mutation or in an altered genetic background), somatically acquired alterations of allelic expression at the Mest locus may occur. 相似文献
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