A method to determine protein digestibility of microdiets for larval and early juvenile fish

A method to evaluate protein quality using in vivo methods was developed for larval fish. FluoSpheres^® fluorescent microspheres (10 μm) were incorporated into two test diets, our standard zein microdiet (ZMD) and a microdiet with identical ingredients except for the replacement of high quality fish meal with the same product cooked for 24 h at 80 °C (ZMD-CF). Several trials were performed to design a reliable method to test digestibility using FluoSpheres^® as a marker. The developed in vivo technique was tested on 35 days posthatch (dph) larval Atlantic cod ( Gadus morhua L.) and two tropical fish species in the early juvenile stage. The method took into account loss of total protein to the faecal pellet and water column. Apparent digestibility of protein in larval cod fed ZMD was significantly higher than that of larvae fed ZMD-CF ( P  < 0.05). A growth study to validate differences between the two diets showed significant differences in growth and survival of larvae fed ZMD versus ZMD-CF ( P  < 0.05). Further validation of our results was indicated through the use of a pH-stat method using enzymes extracted from 35 dph larval cod guts. This novel technique will be advantageous for researchers to evaluate feed ingredients for larval marine fish and is adaptable to many different areas of larval fish nutrition.     

Uptake and excretion of Brucella abortus in tissues of the face fly (Musca autumnalis)

To determine their capacity to host Brucella abortus, face flies were examined 1 to 120 hours after feeding on broth containing bacteria and bovine erythrocytes. Brucella abortus was cultured in large numbers from whole flies for 12 hours after feeding, but not after 72 hours. Histologic analysis showed that brucellae were rapidly taken into the midgut, sequestered from erythrocytes, transiently stored, and shed in the feces; there was no evidence of bacterial replication within epithelial cells. Immunoperoxidase and immunogold techniques revealed that most brucellae in the gut were confined to the lumen by the peritrophic membrane, that brucellae were degraded in secondary lysosomes of midgut epithelial cells, and that intact brucellae passed into connective tissues surrounding the midgut. Bacterial excretion without midgut replication is consistent with transient, but not long-term, insect transmission in nature.     

排灌泵站微机自控清污机的设计

设计了一种新型、应用广泛,经济型的适应性中小排灌泵站除杂草、泡沫塑料的微机自动控制的清污机械,介绍了其结构与工作原理。     

Progress with the legume bacteria in Rhodesia

Progress during eight years of work in Rhodesia with Rhizobium is presented. 370 of the country's 507 known indigenous species of legumes have been examined for nodulation, and all but 13 found to form nodules. A collection of 573 isolates of Rhizobium, 221 of them from other countries, has been built up on a basis of selecting strains for agricultural use. Results of greenhouse tests of nitrogen‐fixing powers of Rhizobium, and of field‐tests of selected strains, are given. A factory is producing inoculants at the rate of 9000 units a year. A survey has shown virtual absence of field‐failure of these inoculants.     

Seasonal effect on infection and development of lesions caused by Cryphonectria parasitica in Castanea sativa

Seasonal variation in the development of chestnut blight, caused by Cryphonectria parasitica, was investigated by inoculating in situ chestnut trees and in vitro excised chestnut segments, at either monthly or 3‐monthly intervals throughout 30 months. Inoculations were made with conidia and mycelium of a virulent isolate and with mycelium of a hypovirulent isolate. Conidial inoculations of living sprouts or excised segments between May and July resulted in the greatest incidence of infection whereas inoculations in autumn and winter, in vitro as well as in situ, did not reveal any visible disease. However, from these symptomless inoculated stems, C. parasitica was isolated 3 months after inoculation. Inoculations with the mycelium of the virulent isolate always resulted in lesions, except in January 1999, and the greatest rate of lesion development occurred for inoculations made in the spring and summer. There was a significant seasonal effect on lesion development. Lesions caused by the hypovirulent isolate, smaller than those caused by the virulent isolate, followed a similar seasonal pattern. The same seasonal variations were observed for inoculations in vitro of excised segments. Relative water content (RWC) of chestnut bark significantly varied with bark sampling date. The rate of lesion development in sprouts significantly correlated with average minimum (ATn) and maximum (ATx) temperatures and the sum of rainfall during inoculation period, with the rate of lesion development measured in excised segments 10 days after inoculation (R10d) and with RWC measured on the day of inoculation. In multiple regression models, variables ATx and R10d best explained variation in lesion development.     

Identical genotypes of community‐associated MRSA (ST59) and livestock‐associated MRSA (ST9) in humans and pigs in rural China

This study investigated the prevalence of MRSA in samples taken in households, with and without backyard pigs in villages in a rural area of Shandong Province, China. Community‐associated MRSA and livestock‐associated MRSA, belonging to ST59 and ST9, respectively, were identified in both humans and pigs. The genotypic and phenotypic comparison of isolates indicates that bidirectional transmission of MRSA has occurred between humans and pigs in the villages.     

Emergence of "new" viral zoonoses]

In the last two to three decades a significant increase of viral zoonotic infections was observed. These zoonoses are not only newly (or previously unrecognized) emerging diseases, but also due to the reappearance of diseases thought to have been defeated (re-emerging diseases). "New" viral diseases can arise when viruses broaden their host-range (monkey poxvirus; equine morbillivirus), or can be a consequence of intrinsic properties of the virus itself, such as high mutation rates (influenza A virus). Most new or reemerging viral zoonoses are due to infections with hemorrhagic viruses. Many of them are transmitted by insects (arboviruses, e.g. yellow fever virus) or by rodents (e.g. Hanta viruses), others by contact with patients and nosocomial infections (e.g. Ebola virus). The emergence and increase of these diseases are a consequence of anthropogenic environmental changes, such as distortions of the ecological balance and changes in agriculture. In addition, the uncontrolled growth of the cities in tropical and subtropical regions without improvement of the public health measures and the increasing international animal trade and travel also favour the spread and recurrence of these diseases.     

Can light intensity influence the tolerance of Synedrellopsis grisebachii to glyphosate?

Plant susceptibility to herbicides is related to several factors, including the environmental conditions under which the plants develop. Two experiments were carried out using Synedrellopsis grisebachii plants in two different developmental stages (vegetative and reproductive), with the goal of studying plant susceptibility to the herbicide, glyphosate, and the dependence of this susceptibility on light intensity (full sunlight and 70% shading), correlated with leaf anatomy. The experimental design for both experiments was completely randomized, with a 2 × 7 factorial scheme, with two light intensities and seven different doses of glyphosate (0D, 1/4D, 1/2D, D, 2D, 4D and 6D, where D is the recommended dose of 1800 g ae ha^?1) as the factors and four replicates per treatment. The leaf anatomy was characterized with optical and scanning electron microscopy. The plants that were grown in full sunlight were more tolerant of glyphosate because of thickening of the adaxial epidermis, parenchyma and main vein structures, which required higher glyphosate doses for effective weed control. The plants that were in the reproductive stage were more tolerant of glyphosate, probably because of lower glyphosate absorption and translocation to the reproductive organs.