Adrenaline: mechanism of action on the pacemaker potential in cardiac Purkinje fibers

The pacemaker potential in Purkinje fibers is generated by a slow fall in potassium current which allows the inward background currents to depolarize the membrane. Adrenaline shifts the relation between activation of the potassium current and membrane potential in a depolarizing direction. Consequently, during the pacemaker potential, the potassium current falls more rapidly to lower values and the inward currents then depolarize the membrane more quickly. The shift in the potassium activation curve produced by adrenaline is large compared to that produced by calcium ions. The molecular action of adrenaline may involve either a large change in the surface charge of the membrane or a change in the dependence of the potassium permeability on the local electric field.     

双孢蘑菇生活史的多样性

 野生双孢蘑菇在形态、生态、生理、遗传等方面具有广泛的多样性。大部分野生和栽培的双孢蘑菇菌株和品种具有次级同宗配合的性特征，也有少数野生菌株属于异宗配合的类型。通过对采自英国牛津的野生双孢蘑菇菌株96.4的单孢菌株的形态、生长、交配、结实、RAPD和AFLP遗传标记等方面研究的分析，发现该菌株具有次级同宗配合和异宗配合的双重交配方式，成为独立的一群。研究表明野生双孢蘑菇在生活史方面具有丰富的多样性。     

Protein kinase inhibitors: insights into drug design from structure

Protein kinases are targets for treatment of a number of diseases. This review focuses on kinase inhibitors that are in the clinic or in clinical trials and for which structural information is available. Structures have informed drug design and have illuminated the mechanism of inhibition. We review progress with the receptor tyrosine kinases (growth factor receptors EGFR, VEGFR, and FGFR) and nonreceptor tyrosine kinases (Bcr-Abl), where advances have been made with cancer therapeutic agents such as Herceptin and Gleevec. Among the serine-threonine kinases, p38, Rho-kinase, cyclin-dependent kinases, and Chk1 have been targeted with productive results for inflammation and cancer. Structures have provided insights into targeting the inactive or active form of the kinase, for targeting the global constellation of residues at the ATP site or less conserved additional pockets or single residues, and into targeting noncatalytic domains.     

Effect of light intensity on self-feeding of rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> reared individually

The self-feeding abilities of individually reared rainbow trout Oncorhynchus mykiss were investigated under four different light intensities (7×10⁻², 1×10°, 5×10¹, and 7×10² lx). There was no significant effect of light intensity on self-feeder learning ability and food wastage (which did not exceed 0.5%). However, there was high individual variability in the ability irrespective of light intensity. The total number of trigger actuations was significantly higher at 1×10° lx than at 7×10⁻² and 5×10¹ lx. Feeding patterns during the light phase of a day were classified as early or late in relation to the timing of significant peaks in fish feeding, or non-steady. The last pattern was defined when significant peaks were not observed. Under 7×10⁻², 1×10°, or 7×10² lx, a non-steady feeding pattern was the most common. Early feeding appeared only under the 1×10° lx regime with the random pattern, while the late pattern was observed under 7×10⁻², 5×10¹, and 7×10² lx. Under 5×10¹ lx regime half of the fish fed in the afternoon. These results suggest that light intensity can affect the timing of feeding judged from the frequency of pulling bite tags, but does not affect waste or learning period.     

Eucalypt plantations as habitat for birds on previously cleared farmland in south-eastern Australia

In parts of Australia, extensive areas of cleared land are now being planted with commercial plantations of native eucalypts. Questions arise about the extent to which such plantations can rectify previous loss of habitat and contribute to biodiversity conservation. This study assessed abundance of bird species (as one aspect of biodiversity) on 105 sites (25 cleared land, 58 plantations and 22 native forest) in two regions of rural Victoria, south-eastern Australia. Generalised linear modelling was used to assess some of the landscape and habitat variables that contributed to the value of plantation sites for particular groups of bird species. These models demonstrated the importance of on-site habitat variables in explaining the abundance of groups of bird species, with landscape context making small additional contributions.Mean abundance of forest and woodland birds was higher in eucalypt plantations than cleared farmland, and marginally lower than in native forest. Patterns differed between bird guilds. For example, insectivores that forage in the canopy and tall shrub layers were at least as common in plantations as in native forest, with birds in the latter group using young eucalypts as if they were tall shrubs. Birds that forage from open ground among trees were more common in plantations than native forest, and may benefit substantially from the new habitat fortuitously provided for them. This group includes several species that have declined in natural woodland habitats. Nectarivores, carnivores and birds that forage among low shrubs were less common in plantations than in native forest. Insectivores that forage from eucalypt bark made little use of plantations. Different approaches to plantation design and management would be needed to cater for groups such as these. Specific measures include planting of rough-barked eucalypts in addition to smooth-barked species, and provision of artificial hollows. Retention of existing remnants of native forest (e.g. old trees and forest patches) is a priority, to supply habitat elements that would otherwise be missing for long periods.     

Distribution of propionibacteria on dogs: A preliminary report of the findings on 11 dogs

A microdissection technique was used to investigate the flora of the canine skin surface and hair follicle. Anaerobic incubation revealed a species of Propionibacterium on the skin of seven of 11 normal dogs. The organism had cultural and biochemical similarities to Propionibacterium acnes. Analysis of the distribution of the organism revealed significant differences between carriage on males and females, between dogs with long and shorthaired coats and between dogs with coarse and fine hair. When present, the regional distribution of P acnes was similar to that found on man, with higher numbers found on the trunk than on the feet.     

First-choice therapy for dogs presenting with diarrhoea in clinical practice

Computerised referral histories were reviewed for dogs admitted to the University of Liverpool Small Animal Teaching Hospital between January 2000 and December 2008 with diarrhoea among the clinical signs. A total of 371 cases presenting to the referring veterinary surgeon were included in the study, and information was compiled regarding signalment, clinical signs and treatment given at the initial consultation. Various breeds, ages and sexes were represented. Antibacterials were used in 263 (71 per cent) cases, steroids in 71 (19 per cent) cases and miscellaneous antidiarrhoeal products (including probiotics, prebiotics, adsorbents and antimotility drugs) in 98 (26 per cent) cases. Other drugs used included antiemetics (48 of 371 [13 per cent] cases), gastric protectants (37 of 371 [10 per cent] cases) and sulfasalazine (26 of 371 [7 per cent] cases). Antibacterial administration was positively associated with hyperthermia (odds ratio [OR]=2.97, P=0.012) and anorexia (OR=2.17, P=0.0075), but negatively associated with both weight loss (OR=0.55, P=0.036) and tenesmus (OR=0.43, P=0.035). In contrast, use of antidiarrhoeal products was positively associated with the presence of faecal mucus (OR=1.77, P=0.043), and negatively associated with vomiting (OR=0.57, P=0.025) and weight loss (OR=0.52, P=0.033).