Inhibition of Chlorophyll Synthesis and Enzymes of Nitrogen Assimilation by Selenite in Excised Maize Leaf Sefments during Greening

Supply of 0.1 mM sodium selenite (Na₂SeO₃ to excised maize leaf segments during greening reduced total chorophylls and inhibited in vivo nitrate reductase activity (NRA). Inhibition of chlorophyll formation by selenite was affected by ammonium but remained unaltered by nitrate. Selenite also inhibited NADH-glutamate dehydrogenase (NADH-GDH) and NADH-glutamate synthase (NADH-GOGAT) activities. Inclusion of ammonium enhanced the inhibition of NADH-GDH activity by selenite but decreased the inhibition of NADH-GOGAT activity by selenite. The results suggest the involvement of the glutamine synthetase/glutamate synthase (GS/GOGAT) pathway of ammonia assimilation in selenite toxicity during chlorophyll formation in greening maize leaf segments.     

Do boating and basking mix? The effect of basking disturbances by motorboats on the body temperature and energy budget of the northern map turtle

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A review of thermal stress in cattle

Cattle control body temperature in a narrow range over varying climatic conditions. Endogenous body heat is generated by metabolism, digestion and activity. Radiation is the primary external source of heat transfer into the body of cattle. Cattle homeothermy uses behavioural and physiological controls to manage radiation, convection, conduction, and evaporative exchange of heat between the body and the environment, noting that evaporative mechanisms almost exclusively transfer body heat to the environment. Cattle control radiation by shade seeking (hot) and shelter (cold) and by huddling or standing further apart, noting there are intrinsic breed and age differences in radiative transfer potential. The temperature gradient between the skin and the external environment and wind speed (convection) determines heat transfer by these means. Cattle control these mechanisms by managing blood flow to the periphery (physiology), by shelter-seeking and standing/lying activity in the short term (behaviourally) and by modifying their coats and adjusting their metabolic rates in the longer term (acclimatisation). Evaporative heat loss in cattle is primarily from sweating, with some respiratory contribution, and is the primary mechanism for dissipating excess heat when environmental temperatures exceed skin temperature (~36°C). Cattle tend to be better adapted to cooler rather than hotter external conditions, with Bos indicus breeds more adapted to hotter conditions than Bos taurus. Management can minimise the risk of thermal stress by ensuring appropriate breeds of suitably acclimatised cattle, at appropriate stocking densities, fed appropriate diets (and water), and with access to suitable shelter and ventilation are better suited to their expected farm environment.     

Methods for detection of immune-mediated neutropenia in horses, using antineutrophil serum of rabbit origin

Equine neutrophil antibody was raised in rabbits inoculated with equine neutrophils isolated to purity greater than 99.0%, using Percoll density-gradient sedimentation. Neutrophil antibody was detected by use of agar gel diffusion, leukoagglutination, indirect immunofluorescence, staphylococcal protein A and streptococcal protein G binding, and phagocytic inhibition techniques. Precipitin lines and leukoagglutination were seen in antiserum dilutions of 1:4 and 1:64, respectively. The specific nature of leukoagglutination was characterized by the formation of rosette-like clumps of neutrophils. Specific bright membranous fluorescence was seen in neutrophils treated with the antiserum and exposed to fluorescein-conjugated goat anti-rabbit immunoglobulin, and staphylococcal protein A and streptococcal protein G. Whereas the indirect immunofluorescence and protein G-binding tests were equally sensitive and resulted in titer of 1:256, the protein A-binding test was less sensitive and resulted in titer of only 1:32. Nonspecific binding of protein A and protein G was noticed as uniform or patchy cellular fluorescence in a small number of neutrophils. Treatment of neutrophils with antiserum up to dilution of 1:8 resulted in a significant (P less than 0.05) suppression of phagocytosis of opsonized zymosan particles. Thus, protein G-binding and indirect immunofluorescence tests are highly sensitive to detect neutrophil antibody and may be used to diagnose immune-mediated neutropenias in horses and, possibly, in other animal species.     

Haematological changes in buffalo calves inoculated with Escherichia coli endotoxin and corticosteroids

Haematological studies were conducted on 10 clinically normal water buffalo calves to determine leucocytic responses to Escherichia coli endotoxin, prednisolone and dexamethasone. Intravenous injection of 10 micrograms endotoxin induced minimal decreases in leucocyte numbers, whereas 20, 50 and 100 micrograms produced a marked leucopenia within one hour. Moderate to marked leucopenia, neutropenia and lymphopenia persisted for three to 14 hours. Significant rebound neutrophilia was evident at six to eight hours after inoculation in calves given only 10 and 20 micrograms. Intramuscular injection of prednisolone (100 mg) and dexamethasone (5 mg) produced increases in total leucocyte counts and neutrophil numbers within two hours. Moderate to marked leucocytosis and neutrophilia persisted for eight to 24 hours. Lymphocyte response was unlike that in other species in that lymphopenia was not a consistent feature of the corticosteroid response. A transient monocytosis was seen following administration of prednisolone but not of dexamethasone, while eosinopenia and basopenia developed in both cases. In conclusion, endotoxin and corticosteroid induced changes in total and differential leucocyte counts in water buffalo were largely similar to those seen in cattle.     

Prothrombin time and activated partial thromboplastin time using a point‐of‐care analyser (Abaxis VSpro®) in Bennett's wallabies (Macropus rufogriseus)

There are few reports of coagulation times in marsupial species. Blood samples collected from 14 Bennett's wallabies (Macropus rufogriseus) under anaesthesia during routine health assessments were analysed for prothrombin time (PT) and activated partial thromboplastin time (aPTT) using a point‐of‐care analyser (POC) (Abaxis VSPro®). The wallabies had an aPTT mean of 78.09 s and median of 78.1 s. The PT for all wallabies was greater than 35 s, exceeding the longest time measured on the POC. Although PT was significantly longer, aPTT was similar to the manufacturer's domestic canine reference range.     

Shape changes in caprine erythrocytes exposed to chlorpromazine and lysolecithin

Stomatocytic and echinocytic transformations of caprine erythrocytes were studied in vitro using chlorpromazine as a stomatocyyic agent and lysolecithin as an echinocytic agent. Morphologic changes in erythrocytes generally varied with the cell shape and the concentration of the substances used. Discoytic, triangular, and pear-shaped red cells common to normal goats, exhibited classical stomatocytic and echinocytic changes with formation of spherostomatocytes, sphero-echinocytes, and spherocytes. In comparison, fusiform and spindle-shaped red cells found in certain Angora goats seemed less prone to shape changes and required greater concentrations of the inducing agents to effect such changes. Chlorpromazine at higher concentrations also inflicted localized membrane damage in form of tiny pits and lysolecithin likewise induced formation of fragile smooth or beaded filaments.     

Ligation of the caudal mesenteric artery during resection and anastomosis of the colorectal junction for annular adenocarcinoma in two dogs

An 8-year-old terrier cross and a 10-year-old German Shorthaired Pointer presented to the University Veterinary Centre, Sydney, for investigation of long-standing tenesmus and dyschezia. Both patients had an annular adenocarcinoma at the colorectal junction. Exploratory laparotomy was performed and the affected large intestinal segment was removed by resection and anastomosis. In both dogs, the caudal mesenteric artery was intimately associated with the mass, necessitating its ligation and transection. Postoperatively, there was no evidence of anastomosis breakdown in either case and both animals recovered well from surgery. The dogs were euthanased 8 and 10 months, respectively, after surgery because of clinical signs relating to metastatic disease.     

Agrobacterium tumefaciens mediated genetic transformation and regeneration of Morus alba L.

An efficient method was established for genetic transformation of Morus alba clone M5 using Agrobacterium tumefaciens mediated gene transfer. Cotyledon explants from in vitro grown seedlings were co-cultivated with disarmed strain LBA 4404 harbouring the binary vector p^BI121 carrying chimeric β-glucuronidase (GUS) and neomycin phosphotransferase (npt II) genes. Maximum transformation frequency of 18.60% was recorded with 48 h of pre-conditioning followed by co-cultivation for the same duration. Expression and presence of transgene was confirmed by histochemical test and polymerase chain reaction. The transgenic plants were micropropagated and successfully acclimatised.     

Preliminary observations on the pharmacokinetics of CDRI compound 81/470 in calves

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