Cross-protective immunity and the serological classification system for Bacteroides nodosus

The relationship between the serological classification system for serogroup B and for serogroup H of Bacteroides nodosus and cross-protection between subgroups within these serogroups was examined. Protection against ovine footrot following vaccination was achieved against other subgroup strains provided sufficient cross-reactive antibody was induced by shared pilus antigens. Within serogroup B, better cross-protection against one subgroup was obtained with a pili vaccine than a whole cell vaccine which correlated with higher pilus antibody titres induced by the former. For serogroup H, a lack of cross-protection and serological reactivity between subgroups was demonstrated, which indicates that the prototype strain of subgroup H2 should be designated a new serogroup.     

A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting

Direct water electrolysis was achieved with a novel, integrated, monolithic photoelectrochemical-photovoltaic design. This photoelectrochemical cell, which is voltage biased with an integrated photovoltaic device, splits water directly upon illumination; light is the only energy input. The hydrogen production efficiency of this system, based on the short-circuit current and the lower heating value of hydrogen, is 12.4 percent.     

腐霉对甲霜灵抗性测定及其生物防治

测定了腐霉属的8个种209个菌株对甲霜灵在浓度为0.5和50ug/ml时的抗性，从实验中观察到不同菌株对甲霜灵抗性变化的范围非常大，有95株在0.5ug/ml时，菌丝即停止生长，在20株在50ug/ml时，菌丝生长速度与对照几乎一样。经鉴定，这209株菌中，优势种为终极腐霉(Pythium ultimum）和刺腐霉(P.spinosum)。20株高抗菌中,P.ultimum占16株，P.irregulare占2株，P.spinosum和P.graminicola各占1株。盆栽试验表明：假单胞菌株Pseudomonas sp.CR56对高抗菌株P.ultimum ONCUR01引起黄瓜苗期猝倒病具有显著的防效，防效与甲霜灵和五氯硝基苯相比，达到极显著差异。     

Immunohistochemical detection of PrP in the medulla oblongata of sheep: the spectrum of staining in normal and scrapie-affected sheep

Sections of the medulla oblongata from the brains of sheep were examined for prion protein (PrP) by immunohistochemistry. On the basis of the morphology and neuroanatomical distribution of the deposits, distinct disease-associated patterns of PrP deposition were identified in scrapie-affected sheep, suggesting at least four distinct phenotypes of scrapie. In addition, clearly defined patterns of PrP deposition, readily distinguished from the disease-associated PrP deposits, were identified in some normal sheep from scrapie-free flocks. In five sheep, believed to be preclinically affected by scrapie, PrP deposition of a disease-specific type but of restricted distribution was identified, demonstrating the sensitivity of the technique for the diagnosis of scrapie. The neuroanatomical distribution of these early PrP deposits suggest that the route of entry of the scrapie agent into the brain is via parasympathetic motor neurons in the vagus nerve which innervate the gastrointestinal tract.     

Relationship of blood corticosterone, immunoglobulin and haematological values in young crocodiles (Crocodylus porosus) to water temperature, clutch of origin and body weight

Objective To examine whether sub-optimal temperature induced stress and immunosuppression in farmed saltwater crocodile (Crocodylus porosus) hatchlings. Design A clinico-pathological study. Animals A total of 140 hatchlings were used. Procedure Body weight and length, plasma corticosterone and immunoglobulin concentrations and total and differential white blood cell counts were measured in 140 hatchlings from five clutches divided between five water temperature treatment groups. Initially all groups were housed at 32°C for 10 weeks, then two groups (L, LC) were changed to low temperature (28°C) and two groups (H, HC) to high temperature (36°C), while one group (C) remained at 32°C. The LC and HC groups were maintained at these temperatures for 10 days, after which the water temperature of both groups was returned to 32°C. Blood samples were collected twice (at 6 and 9 weeks of age) before the initial temperature change, and at 10 days and 4 weeks after the initial temperature change (at 11.5 and 14 weeks of age). Results Except for an increase in plasma corticosterone in the HC group and a decrease in the L group when the temperature change was first introduced, changes in plasma corticosterone were not significant. There were no significant changes in immunoglobulin concentrations. There were, however, significant decreases in the total white cell and lymphocyte counts in the LC group after the temperature was decreased to 28°C, and an increase in these counts after water temperature was returned to 32°C. Clutch of origin had significant effects on body weight and length gains, and there were negative relationships between body weight and corticosterone concentrations and between body weight and immunoglobulin concentrations. Conclusions As haematological changes indicative of stress were not associated with significant changes in serum corticosterone, immunosuppression in young crocodiles may be independent of the hypothalamic-pituitary-adrenal cortical axis.