Direct 1H n.m.r. determination of the stereochemical course of hydrolyses catalysed by glucanase components of the cellulase complex

The stereochemical courses of the hydrolyses catalysed by three glycosidases have been determined directly by 1H nmr. The anomeric configuration of the initially formed product was ascertained in each case by observation of the chemical shift and coupling constant of the anomeric proton at the new hemiacetal centre. Two of the enzymes investigated, an endo-glucanase and an exo-glucanase are components of the cellulase complex of Cellulomonas fimi. The third enzyme is the beta-glucosidase from almond emulsin. Two of these enzymes, the exo-glucanase and the almond beta-glucosidase catalysed hydrolysis with retention of anomeric configuration, in agreement with previous observations on the almond enzyme. The endo-glucanase catalysed hydrolysis with inversion of configuration, this result being confirmed by optical rotation measurements. This 1H nmr approach has several advantages over other techniques in that it is applicable to a wide variety of glycosidases and substrates and it is non-destructive, allowing recovery of the enzyme.     

Complete genome sequence of Arcanobacterium haemolyticum type strain (11018)

Arcanobacterium haemolyticum (ex MacLean et al. 1946) Collins et al. 1983 is the type species of the genus Arcanobacterium, which belongs to the family Actinomycetaceae. The strain is of interest because it is an obligate parasite of the pharynx of humans and farm animal; occasionally, it causes pharyngeal or skin lesions. It is a Gram-positive, nonmotile and non-sporulating bacterium. The strain described in this study was isolated from infections amongst American soldiers of certain islands of the North and West Pacific. This is the first completed sequence of a member of the genus Arcanobacterium and the ninth type strain genome from the family Actinomycetaceae. The 1,986,154 bp long genome with its 1,821 protein-coding and 64 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Characterizing the pH-dependent stability and catalytic mechanism of the family 11 xylanase from the alkalophilic Bacillus agaradhaerens

The xylanase, BadX, from the alkalophilic Bacillus agaradhaerens was cloned, expressed and studied in comparison to a related family 11 xylanase, BcX, from B. circulans. Despite the alkaline versus neutral conditions under which these bacteria grow, BadX and BcX both exhibit optimal activity near pH 5.6 using the substrate o-nitrophenyl beta-xylobioside. Analysis of the bell-shaped activity profile of BadX yielded apparent pK(a) values of 4.2 and 7.1, assignable to its nucleophile Glu94 and general acid Glu184, respectively. In addition to having an approximately 10-fold higher k(cat)/K(m) value with this substrate at pH 6 and 40 degrees C, BadX has significantly higher thermal stability than BcX under neutral and alkaline conditions. This enhanced stability, rather than a shift in its pH-optimum, may allow BadX to hydrolyze xylan under conditions of elevated temperature and pH.     

Assessing biodiversity with species accumulation curves; inventories of small reptiles by pit‐trapping in Western Australia

Abstract We examined 11 non‐linear regression models to determine which of them best fitted curvilinear species accumulation curves based on pit‐trapping data for reptiles in a range of heterogeneous and homogenous sites in mesic, semi‐arid and arid regions of Western Australia. A well‐defined plateau in a species accumulation curve is required for any of the models accurately to estimate species richness. Two different measures of effort (pit‐trapping days and number of individuals caught) were used to determine if the measure of effort influenced the choice of the best model(s). We used species accumulation curves to predict species richness, determined the trapping effort required to catch a nominated percentage (e.g. 95%) of the predicted number of species in an area, and examined the relationship between species accumulation curves with diversity and rarity. Species richness, diversity and the proportion of rare species in a community influenced the shape of species accumulation curves. The Beta‐P model provided the best overall fit (highest r²) for heterogeneous and homogeneous sites. For heterogeneous sites, Hill, Rational, Clench, Exponential and Weibull models were the next best. For homogeneous habitats, Hill, Weibull and Chapman–Richards were the next best models. There was very little difference between Beta‐P and Hill models in fitting the data to accumulation curves, although the Hill model generally over‐estimated species richness. Most models worked equally well for both measures of trapping effort. Because the number of individuals caught was influenced by both pit‐trapping effort and the abundance of individuals, both measures of effort must be considered if species accumulation curves are to be used as a planning tool. Trapping effort to catch a nominated percentage of the total predicted species in homogeneous and heterogeneous habitats varied among sites, but even for only 75% of the predicted number of species it was generally much higher than the typical effort currently being used for terrestrial vertebrate fauna surveys in Australia. It was not possible to provide a general indication of the effort required to predict species richness for a site, or to capture a nominated proportion of species at a site, because species accumulation curves are heavily influenced by the characteristics of particular sites.     

Thermoregulation by an Australian murine rodent, the ash-grey mouse (Pseudomys albocinereus)

We examine here the thermal physiology of the ash-grey mouse, as there is a paucity of data to explain how Australian rodents meet thermoregulatory demands. Most ash-grey mice remained normothermic over a range of ambient temperatures (10°C to 30°C), although they became hyperthermic at high ambient temperatures. One individual entered torpor at ambient temperatures of 20°C and 25°C, with minimal body temperatures of 24.5°C and 28.4°C respectively, before spontaneously arousing. This is the first evidence of torpor use by an Australian murine rodent. Our data suggest that although ash-grey mice have the physiological ability to use torpor, it is used rarely, presumably due to other behavioural and physiological adaptations. Their higher-than-expected basal metabolic rate (1.56±0.25mLO(2)g(-1)h(-1)) indicates that ash-grey mice do not have a frugal approach to energy expenditure. Other standard physiological variables were typical of a generalised rodent. A readily-available omnivorous diet, nocturnal activity, semi-fossorial habit and social behaviour presumably allow a high energy lifestyle. A reluctance to use torpor, despite an apparent physiological ability to do so, supports the idea that the use of torpor reflects a net balance between the costs and benefits of a heterothermic thermoregulatory strategy.     

Potential non-target impact of Microctonus aethiopoides Loan (Hymenoptera: Braconidae) on Cleopus japonicus Wingelmüller (Coleoptera: Curculionidae), a biocontrol agent for putative release to control the butterfly bush Buddleja davidii Franchet in New Zealand

Abstract  Cleopus japonicus Wingelmüller (Coleoptera: Curculionidae) is being considered for release to control buddleia Buddleja davidii in New Zealand. As part of the pre-release testing, Moroccan and Irish biotypes of the solitary endoparasitoid Microctonus aethiopoides Loan (Hymenoptera: Braconidae) were evaluated for potential non-target impacts on adult C. japonicus should release occur. Laboratory experiments evaluated both the behavioural and physiological suitability of C. japonicus to both biotypes of the parasitoid. Parasitoid behavioural attraction was assessed using the pathenogenic bacterium Serratia marcescens (Enterobactereaceae), as an indicator of ovipositor penetration. Physiological suitability was assessed by comparing parasitism of C. japonicus with the natural hosts of the respective parasitoid biotypes. The parasitoid-bacteria study showed that C. japonicus was behaviourally acceptable to both Moroccan and Irish M. aethiopoides , with the two experiments producing 34% and 8% mortality, respectively. Cleopus japonicus did not support development of either Moroccan or Irish M. aethiopoides biotypes. None of the weevils dissected at the end of the experiment contained immature parasitoids. Comparison between unexposed and parasitoid-exposed C. japonicus found no difference in premature mortality during the experiment nor in the number of fully reproductive females at its conclusion. The results of this study predict that should C. japonicus be released, the potential impact of M. aethiopoides on field populations will be negligible.     

Vimentin and leukocyte common antigen-negative molding cells in pleural effusions of patients with small cell lung carcinoma

OBJECTIVE: To determine whether the presence of vimentin and leukocyte common antigen (LCA)-negative molding cells (VLNMC) could help in identifying rare small cell lung carcinoma (SCLC) cells. STUDY DESIGN: Thirty-four cell blocks of pleural effusions (PEs) from 26 patients with confirmed SCLC were stained immunohistochemically with vimentin and LCA antibodies and compared with hematoxylin and eosin-stained preparations. RESULTS: VLNMC were present in 22/22 PEs originally diagnosed as positive or atypical/suspicious for SCLC. Focal vimentin staining was seen in SCLC in 10/22 cases, and 1 case showed many vimentin-positive SCLC cells. One of 11 PEs originally interpreted as negative showed rare groups of VLNMC. This was supported by a subsequent PE obviously positive for SCLC. CONCLUSION: Immunoperoxidase stains for vimentin and LCA highlight SCLC in PEs as VLNMC; however, morphologic criteria must prevail in making the final diagnosis.