Improved Coated Vesicle Isolation Allows Better Characterization of Clathrin Polypeptides

Postmicrosomal pellets from plant sources are grossly contaminatedwith nbosomes. Previous purifications of clathrin coated vesicles(CCV) from such subcellular fractions have therefore often involvedan RNase treatment. Performed at 30°C, this step inherentlycarries with it the dangers of proteolysis. We document herea method for CCV isolation which avoids this. Through the inclusionof suitable antiproteases in the homogenizing and subsequentisolation media, we have also been able to improve the qualityof CCV recovered from plant tissues. As a result we have tentativelybeen able to identify clathrin light chains from zucchini hypocotyland pea cotyledon CCV. Similar to light chains from bovine brainthese polypeptides are heat stable, can be solubilized fromneutralized TCA precipitates, bind calcium and clathrin heavychains. However, in contrast to brain CCV the two light chainsof plant CCV are some 10 kDa heavier. Key words: Antiproteases, Ca²⁺-binding, clathrin coated vesicles, clathrin heavy chains, clathrin light chain(s), heat stability, pea cotyledons, RNase, zucchini hypocotyls     

The effects of ecology on life history strategies and metabolic disturbances during development: an example from the African bovids

Life history theory predicts environmental factors to affect changes in life history strategies. However, owing to the interrelationships between body mass and life history variables, it is difficult to discern causal relationships, especially in large-bodied mammals and using a comparative approach. The situation is exacerbated in palaeobiologi-cal studies, where many of the variables cannot be observed directly. Specifically, mortality risk has been identified as one of the most important factors determining life history strategies, but its assessment is difficult. This hampers analyses of life history evolution. This study thus explored the possibility to extract previously untapped information from hard tissue, i.e. teeth, which may be useful for life history reconstruction. Histological sections of 25 molars of bovids, representing all subfamilies and spanning a wide range of body masses, were analysed with regard to: (i) molar crown formation times in relation to female body mass and gestation length, and (ii) metabolic disturbances from early to late forming teeth in relation to habitat type occupied, diet consumed and habitual walking style employed. It was found that molar crown formation times in bovids are highly correlated with gestation length once the effects of body mass have been removed. This differs from primates and indicates similarities in pre- and postnatal growth rates in these mammals. Closed-habitat species exhibit relatively fewer disturbances during development than open-country species, but the reverse holds for adult specimens. This accords with what is known about the ecological and behavioural adaptations of the species and is predicted by life history theory. It could thus be confirmed that teeth may provide vital information about life history variables. Exploitation of this information will allow hypotheses to be tested regarding the evolutionary changes in life history strategies of extinct species.     

The species–area relationship in centipedes (Myriapoda: Chilopoda): a comparison between Mediterranean island groups

The present study article examines the shapes of centipede species–area relationships (SARs) in the Mediterranean islands, compares the results of the linear form of the power model between archipelagos, discusses biological significance of the power model parameters with other taxa on the Aegean archipelago, and tests for a significant small‐island effect (SIE). We used 11 models to test the SARs and we compared the quality‐of‐fit of all candidate models. The power function ranked first and Z‐values was in the range 0.106–0.334. We assessed the presence of SIEs by fitting both a continuous and discontinuous breakpoint regression model. The continuous breakpoint regression functions never performed much better than the closest discontinuous model as a predictor of centipede species richness. We suggest that the relatively low Z‐values in our data partly reflect better dispersal abilities in centipedes than in other soil invertebrate taxa. Longer periods of isolation and more recent island formation may explain the somewhat lower constant c in the western Mediterranean islands compared to the Aegean islands. Higher breakpoint values in the western Mediterranean may also be a result of larger distance to the mainland and longer separation times. Despite the differences in the geological history and the idiosyncratic features of the main island groups considered, the overall results are quite similar and this could be assigned to the ability of centipedes to disperse across isolation barriers. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 146–159.     

Trade‐offs in primate grooming reciprocation: testing behavioural flexibility and correlated evolution

Primates may trade altruistic behaviours, such as grooming, either for itself or for different rank‐related benefits, such as tolerance or agonistic support. Ecological conditions are expected to affect competition and thus the steepness of dominance hierarchies. This, in turn, may influence the value of the different currencies that primates exchange. Thus, it can be hypothesized that, as the dominance hierarchy becomes steeper, more grooming is directed up the hierarchy (in exchange for tolerance or agonistic support) and less grooming is exchanged for other grooming. We assembled a large database of within‐group grooming distribution in primates (38 social groups belonging to 16 species and eight genera) and tested these hypotheses both within species (i.e. comparing different groups of the same species) and between species (using comparative methods that control for phylogenetic relatedness). We found within‐species evidence that steeper dominance hierarchies were associated with more grooming being directed up the hierarchy, and that a trade‐off occurred between the tendency to groom up the hierarchy and the degree of grooming reciprocation (although, in some analyses, only a nonsignificant trend was observed). By contrast, phylogenetically controlled comparisons between species did not reveal evidence of correlated evolution between the steepness of the dominance hierarchy, the tendency to direct grooming up the hierarchy, and the degree of grooming reciprocation. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 439–446.     

蛇根木细胞悬浮培养进行紫杉醇的生物转化

通过理化及光谱学方法,从蛇根木(Rautwolfia serpentina(L.)Benth.et Kurz.)悬浮细胞内分离到3个紫杉醇同系物,高分辨1H-NMR和MS结构分析表明,它们分别为10-脱乙酰紫杉醇、baccatinⅢ和10-deacetylbaccatinⅢ.本实验未检测出紫杉醇的苷化或羟基化衍生物.     

Release of Prostaglandins in Ocular Inflammation in the Rabbit

VARIOUS studies have suggested that prostaglandins (PGs) may be involved in the ocular response to acute inflammation. PGs are present in ocular tissues^1–4 and can reproduce many of the characteristic changes associated with ocular trauma in the rabbit^5–7, cat⁸ and monkey⁹. We therefore examined the possibility that PGs are involved in the response of the rabbit eye to an acute immunological inflammatory reaction. Eighty-four adult albino rabbits of both sexes were used in 8 groups of 6 to 12, but 11 were discarded because uveitis did not develop and 1 because of infection. Uveitis was induced by a single intravitreal injection of a sterile solution of crystallized bovine serum albumin (British Drug Houses). The left eye was anaesthetized with topical 0·4% oxybuprocaine hydrochloride and bovine serum albumin (10 mg in 0·1 ml. normal saline) was then injected slowly into the anterior part of the vitreous. On subsequent days the eyes were examined with a slit-lamp. Immediately after the injection, small amounts of protein and cells appeared in the aqueous and a slight flare was seen. This was probably due to trauma and the eyes usually appeared normal by about the fifth day. On the 9th-15th day signs of uveitis appeared, characterized by a pronounced flare (due to liberation of large quantities of protein and cells into the anterior chamber) and by marked dilatation of iris and ciliary blood vessels. Occasionally, the pupillary margin was seen to adhere to the anterior surface of the lens (posterior synechiae). The contralateral control eye was usually unaffected, but in about 20% of cases fine filaments (probably strands of fibrin) were seen in the anterior chamber when uveitis occurred in the test eye. At the height of the inflammatory response, the animals were anaesthetized with pentobarbitone (25 mg/kg i.V.). The aqueous humour (approximately 0·2 ml./eye) was then withdrawn through a 25G needle and stored immediately at ?20°C. In each group, the aqueous humour samples from the test (left) and control (right) eyes were pooled in separate containers. Biological activity was assayed on the rat fundus preparation¹⁰ in Krebs solution containing atropine, methy-sergide and mepyramine (all 2 × 10^?7 g/ml.). Unextracted samples were assayed in some experiments, whereas in others the PG-like material was first extracted (chloroform method of Unger et al.¹¹). Alkaline hydrolysis (0·2 M NaOH, 45 min, 37° C) was used to distinguish between PGE and PGF compounds and thin layer chromatography was used to separate the PGs (a II solvent system of Gréen and Samuelsson¹²; silica gel plates or impregnated paper¹³, treated with 3% w/v silver nitrate). Cuts of the chromatograms at and between the R_F values of PGE₁, PGE₂ and PGF_2α were eluted with Krebs solution containing excess (0.2 M) NaCl to remove the silver ions prior to extraction for PGs^11,13. Samples of unextracted aqueous humour from the test eyes caused contractions (preceded by a relaxation in 1 of the 5 experiments) of the rat fundus preparation. Since atropine, methysergide and mepyramine were present the spasmogen was not acetylcholine, 5-hydroxytryptamine or histamine. The control aqueous had no effect. The material was PG-like since it extracted into chloroform¹¹ when the aqueous humour was acidified and it caused contractions of the rat fundus which were reduced in parallel with PGE₂ by the selective PG antagonist SC-19220^14,15 (Fig. 1). The biological activity was completely destroyed by alkaline hydrolysis in 3 experiments, indicating E-type prostaglandin (Fig. 1) and approximately halved in another (samples from 2 batches of aqueous humour before chloroform extraction and 2 batches after extraction). PGE₂ incubated at the same time was destroyed whereas PGF_2α was unaffected.     

Characterization of EST derived SSRs from the bay scallop,Argopecten irradians

Interest in bay scallop conservation has resulted in organized stock enhancement efforts and increased attention to fisheries management issues. Genetic markers can facilitate the monitoring of enhancement efforts, characterization of wild populations, and optimize hatchery practices. We have identified eight polymorphic simple sequence repeat markers including one dinucleotide, six trinucleotide and one compound dinucleotide repeats, in expressed sequence tags generated from multiple bay scallop cDNA libraries. The numbers of alleles range from two to five. The expected and observed heterozygosities range from 0.093 to 0.720 and 0.095 to 0.600, respectively.     

Calculations of population differentiation based on GST and D: forget GST but not all of statistics!

G _ST‐values and its relatives (F_ST) belong to the most used parameters to define genetic differences between populations. Originally, they were developed for allozymes with very low number of alleles. Using highly polymorphic microsatellite markers it was often puzzling that G_ST‐values were very low but statistically significant. In their papers, Jost (2008) and Hedrick (2005) explained that G_ST‐values do not show genetic differentiation, and Jost suggested calculating D‐values instead. Theoretical mathematical considerations are often difficult to follow; therefore, we chose an applied approach comparing two artificial populations with different number of alleles at equal frequencies and known genetic divergence. Our results show that even for more than one allele per population G_ST‐values do not calculate population differentiation correctly; in contrast, D‐values do reflect the genetic differentiation indicating that data based on G_ST‐values need to be re‐evaluated. In our approach, statistical evaluations remained similar. We provide information about the impact of different sample sizes on D‐values in relation to number of alleles and genetic divergence.     

The Effect of High Concentrations of Heavy Water on Root Morphogenesis in Zea mays

The effect of high concentrations of heavy water on young rootsof Zea mays was investigated. Submersion for 24 hrs. in solutionsof 80–90 per cent. D₂O will temporarily stop growth ofthe primary root. During the treatment period the root-tip regionswill swell as the result of radial cell enlargement, primarilyin the cortical region. Upon removal from D₂O growth will resume,initially at a slower rate than controls but ultimately at similarmaximum rates. Lateral root production is inhibited in thatportion of the primary root which is the region of elongationat time of treatment. However, in the swollen region lateralroot formation is accentuated. The mitotic index drops sharplyupon introduction of the primary roots into 80 per cent. D₂O.Within 12 hrs. the index drops to zero and remains at this leveluntil the roots are removed from the heavy water. The mitoticindex then rises again, reaching control values within 24 hrs.It is suggested that the gentle, temporary inhibitory actionof D₂O makes this substance a useful tool in morphogenetic investigations.