从肿头综合征鸡分离出产Vero毒素E.coli

本研究从哈尔滨郊区某鸡场肿头综合征（ Ｓ Ｈ Ｓ）鸡分离出 ３ 株血清型为 Ｏ７８ 的埃希氏大肠杆菌（ Ｅ．ｃｏｌｉ）,从鞍山 Ｓ Ｈ Ｓ病料分离出 １ 株血清型为 Ｏ８ 的 Ｅ．ｃｏｌｉ。并证实这 ４ 株 Ｅ．ｃｏｌｉ 能够对 Ｖｅｒｏ 细胞产生毒性作用,与产 Ｖｅｒｏ 毒素的 Ｅ．ｃｏｌｉ一致。对哈尔滨市郊 Ｓ Ｈ Ｓ病鸡做病理组织学观察,主要变化为头部皮下组织,头盖骨气室及鼻粘膜下纤维素性化脓性炎症,水肿和大肠杆菌性肉芽肿,心、肝、肾等器官炎症变化并有大量异嗜性粒细胞和细菌团块。     

Effects of sensor spatial resolution on landscape structure parameters

We examined the effects of increasing grain size from 20 m to 1100 m on landscape parameters characterizing spatial structure in the northern Wisconsin lake district. We examined whether structural parameters remain relatively constant over this range and whether aggregation algorithms permit extrapolation within this range. Images from three different satellite sensors were employed in this study: (1) the SPOT multispectral high resolution visible (HRV), (2) the Landsat Thematic Mapper (TM), and (3) the NOAA Advanced Very High Resolution Radiometer (AVHRR). Each scene was classified as patches of water in a matrix of land. Spatial structure was quantified using several landscape parameters: percent water, number of lakes (patches), average lake area and perimeter, fractal dimension, and three measures of texture (homogeneity, contrast, and entropy). Results indicate that most measures were sensitive to changes in grain size. As grain size increased from 20 m using HRV image data to 1100 m (AVHRR), the percent water and the number of lakes decreased while the average lake area, perimeter, the fractal dimension, and contrast increased. The other two texture measures were relatively invariant with grain size. Although examination of texture at various angles of adjacency was performed to investigate features which vary systematically with angle, the angle did not have an important effect on the texture parameter values. An aggregation algorithm was used to simulate additional grain sizes. Grain was increased successively by a factor of two from 20 m (the HRV image) to 1280 m. We then calculated landscape parameter values at each grain size. Extrapolated values closely approximated the actual sensor values. Because the grain size has an important effect on most landscape parameters, the choice of satellite sensor must be appropriate for the research question asked. Interpolation between the grain sizes of different satellite sensors is possible with an approach involving aggregation of pixels.     

ANTIVIRAL EFFECTS OF BACTERIOCIN AGAINST ANIMAL-TO-HUMAN TRANSMITTABLE MUTATED SARS-COV-2: A SYSTEMATIC REVIEW

• Identification of bacteriocin sources• Classification of bacteriocins• Antiviral pathways of bacteriocinsThe COVID-19 infections caused by SARS-CoV-2 have resulted in millions of people being infected and thousands of deaths globally since November 2019. To date, no unique therapeutic agent has been developed to slow the progression of this pandemic. Despite possessing antiviral traits the potential of bacteriocins to combat SARS-CoV-2 infection has not been fully investigated. This review summarizes the mechanisms by which bacteriocins can be manipulated and implemented as effective virus entry blockers with infection suppression potential properties to highly transmissible viruses through comprehensive immune modulations that are potentially effective against COVID-19. These antimicrobial peptides have been suggested as effective antiviral therapeutics and therapeutic supplements to prevent rapid virus transmission. This review also provides a new insight into the cellular and molecular alterations which have made SARS-CoV-2 self-modified with diversified infection patterns. In addition, the possible applications of antimicrobial peptides through both natural and induced mechanisms in infection prevention perspectives on changeable virulence cases are comprehensively analyzed. Specific attention is given to the antiviral mechanisms of the molecules along with their integrative use with synthetic biology and nanosensor technology for rapid detection. Novel bacteriocin based therapeutics with cutting-edge technologies might be potential substitutes for existing time-consuming and expensive approaches to fight this newly emerged global threat.     

Self-organized discotic liquid crystals for high-efficiency organic photovoltaics

Self-organization of liquid crystalline and crystalline-conjugated materials has been used to create, directly from solution, thin films with structures optimized for use in photodiodes. The discotic liquid crystal hexa-peri-hexabenzocoronene was used in combination with a perylene dye to produce thin films with vertically segregated perylene and hexabenzocoronene, with large interfacial surface area. When incorporated into diode structures, these films show photovoltaic response with external quantum efficiencies of more than 34 percent near 490 nanometers. These efficiencies result from efficient photoinduced charge transfer between the hexabenzocoronene and perylene, as well as from effective transport of charges through vertically segregated perylene and hexabenzocoronene pi systems. This development demonstrates that complex structures can be engineered from novel materials by means of simple solution-processing steps and may enable inexpensive, high-performance, thin-film photovoltaic technology.     

Dietary effects on thyroid hormones in the red drum,Sciaenops ocellatus

Juvenile red drum (Sciaenops ocellatus) were cultured at 25°C on a variety of diets and blood sampled over eight weeks to examine the relationship between growth and plasma thyroid hormone levels. Maximum growth rates were achieved on formulated experimental diets and a simulated natural shrimp diet. Associated with these maximal rates was a significant increase in triidothyronine (T₃), but no consistent change in thyroxine (T₄). Reduced rations of diets resulted in low growth rates associated with significantly lowered levels of T₃ but not T₄. To determine whether weight gain could be increased by application of exogeneous hormone, diets were supplemented with T₃ or T₄ at 2, 10, and 50 mg hormone/kg diet. Significantly elevated T₃ was induced by supplementation with 10 and 50 mg T₃/kg diet, although there were no indications of an anabolic effect of T₃ incorporation, and 50 mg T₃/kg diet was in fact associated with decreased weight gain. Incorporation of T₄ into diets had no effect on growth or T₃, and had effects on T₄ which were small and inconsistent, indicating that T₄ may not be effectively absorbed from the gut. No difference was found in response to hormone feeding between low (6 ppt) or high (35 ppt) water salinity. T₃ levels thus appear to closely parallel growth in fish on unsupplemented diets, whereas T₄ which were small and manipulation. Supplementation with T₃ is not an effective means of stimulating growth in red drum fed optimum diets. Whereas thyroid hormones may function to regulate intermediary metabolism in red drum, elevated endogenous thyroid hormone levels appear adequate to supply tissue needs during juvenile growth in culture.     

Effects of Stem-injected Sucrose on Grain Production, Dry Matter Distribution, and Chlorophyll Fluorescence of Field-grown Corn Plants

A field experiment was conducted to evaluate the effect of long-term exogenous sucrose supply on aspects of corn plant physiology and development during the grain filling period. Concentrated sucrose solution was supplied to corn ( Zea mays L.) stems by an injection technique. This injection technique delivered pressurized solutions through syringe needles sealed to the stem with latex. The pressure was applied to the syringe plunger with ceramic construction bricks. Solutions containing sucrose at 0, 150, and 300 g L⁻¹ were injected over a 32 day period encompassing the duration of the active grain filling period. The primary ears of plants injected with sucrose produced approximately 50% more kernels and 30% more grain weight than those injected with distilled water. The injected internode was also considerably heavier (56%) for plants receiving 300 g sucrose L⁻¹ than plants receiving distilled water. For all measured variables, plants injected with distilled water were either not different from or had larger values than the non-injected controls. After one week sucrose injection caused photo-synthetic inhibition (as measured by chlorophyll fluorescence) in the leaf just above the ear and the ear leaf, and this was more severe for plants receiving 300 g sucrose L⁻¹ than for those receiving 150 g sucrose L⁻¹. For sucrose injected plants, the increased size of the primary ear was concomitant with a large decrease in grain production by the secondary ear and an overall decrease in per plant grain production. These results suggest that the mechanisms for signalling between sinks (the primary and secondary ears) and the primary sink and the source (leaves) are different.     

Pathological changes in the mammary gland and biochemical changes in milk of the goat following oral dosing with leaf of the Avocado (Persea americana)

Two varieties of avocado leaves (Persea americana var Guatemalan and var Mexican) were administered to lactating goats. The Mexican variety was without effect. The Guatemalan variety in doses exceeding 20 g fresh leaf per kg bodyweight, produced damage to the mammary gland with decreased milk production. The lesions were characterised by oedema and reddening, with clots in the large ducts. Microscopically, there was widespread degeneration and necrosis of the secretory epithelium, the necrotic cells sloughing into the lumen. There was no significant cellular inflammatory response. Concentrations of antitrypsin in the milk, indicating changes in vascular permeability, increased rapidly 15 h after a single high dose, coinciding with palpable oedema. Concentrations of NAGase, indicating cell damage, increased after 24 h. Goats given multiple doses followed a similar pattern but the initial response was delayed. The toxic principle, and its mode of action in selectively damaging mammary secretory cells, remains to be determined.