Congruent evolution between whiteflies (Homoptera: Aleyrodidae) and their bacterial endosymbionts based on respective 18S and 16S rDNAs

Whiteflies (family Aleyrodidae) possess heritable eubacterial endosymbionts sustained in specialized organ-like structures called mycetomes. Comparisons of distances between the ash whitefly,Siphoninus phillyreae, and two biotypes (A and B) of the sweetpotato whitefly,Bemisia tabaci, based on sequence analysis of genes for 18S rRNAs (rDNAs), were equivalent to the distances represented by the 16S rDNAs of their respective endosymbionts. This finding indicates that evolutionary divergence in whitefly hosts and their endosymbionts is congruent. The nucleotide sequences of the 18S rDNAs and endosymbiont 16S rDNAs indicate the two biotypes ofB. tabaci are the same species.     

Use of the polymerase chain reaction and 16S rRNA sequences for the rapid detection of Brochothrix spp. in foods

Oligonucleotide primers were designed against rRNA sequences to give a DNA-based PCR assay for the rapid identification/detection of Brochothrix spp. The PCR products could be confirmed by hybridization to an internal oligonucleotide probe. The method successfully and sensitively detected/identified these organisms in pure cultures but was of limited value as a detection method because the detection sensitivity, in relation to conventional plate counts, varied and the assay sensitivity was reduced in the presence of staphylococci. Furthermore, sensitivity was also lost when the assay was applied directly to meat samples. However, a separation step using a lectin (from Agaricus bisporus ) immobilized on magnetic beads prior to the PCR assay, allowed the direct detection of low numbers (> 10 cfu g^-1) of Brochothrix in meat samples within a working day.     

Exercise enhancement by RGS14 disruption is mediated by brown adipose tissue

Enhanced exercise capacity is not only a feature of healthful aging, but also a therapy for aging patients and patients with cardiovascular disease. Disruption of the Regulator of G Protein Signaling 14 (RGS14) in mice extends healthful lifespan, mediated by increased brown adipose tissue (BAT). Accordingly, we determined whether RGS14 knockout (KO) mice exhibit enhanced exercise capacity and the role of BAT in mediating exercise capacity. Exercise was performed on a treadmill and exercise capacity was assessed by maximal running distance and work to exhaustion. Exercise capacity was measured in RGS14 KO mice and their wild types (WT), and also in WT mice with BAT transplantation from RGS14 KO mice or from other WT mice. RGS14 KO mice demonstrated 160 ± 9% increased maximal running distance and 154 ± 6% increased work to exhaustion, compared to WT mice. RGS14 KO BAT transplantation to WT mice, resulted in a reversal of phenotype, with the WT mice receiving the BAT transplant from RGS14 KO mice demonstrating 151 ± 5% increased maximal running distance and 158 ± 7% increased work to exhaustion, at three days after BAT transplantation, compared to RGS14 KO donors. BAT transplantation from WT to WT mice also resulted in increased exercise performance, but not at 3 days, but only at 8 weeks after transplantation. The BAT induced enhanced exercise capacity was mediated by (1) mitochondrial biogenesis and SIRT3; (2) antioxidant defense and the MEK/ERK pathway, and increased hindlimb perfusion. Thus, BAT mediates enhanced exercise capacity, a mechanism more powerful with RGS14 disruption.     

Inherited prion disease (PrP lysine 200) in Britain: two case reports.

OBJECTIVE--To identify cases of inherited prion diseases in Britain and to assess their phenotypic features. DESIGN--Screening study of patients suspected clinically to have Creutzfeldt-Jakob disease and other neurodegenerative diseases by prion protein gene analysis. SETTING--Biochemical research department. SUBJECTS--Patients suspected to have Creutzfeldt-Jakob disease and other neurodegenerative diseases. RESULTS--Two patients with symptoms characteristic of sporadic Creutzfeldt-Jakob disease were found to have inherited prion protein disease (PrP lysine 200), with a mutation at codon 200 of the prion protein gene. Both were homozygous at codon 129 of the gene. One patient was a man aged 58 of British descent while the other was of Libyan Jewish origin. CONCLUSION--Two foci of inherited prion disease are known, among Libyan Jews and in Slovakia. A separate British focus of the disease may also exist. Heterozygosity at codon 129 may lead to reduced penetrance of the mutation.     

Anti-predator defences of a web-building spider, Holocnemus pluchei (Araneae, Pholcidae)

Anti-predator defence behaviour of Holocnemus pluchei (Araneae, Pholcidae) was studied in the laboratory and the field. Bouncing, in which this web-building spider moves its body rapidly up and down while keeping its legs on the silk, was the most frequent response to disturbance. Less often, H. pluchei left the web when disturbed. Experiments were carried out to determine the types of stimuli that elicited bouncing and leaving the web: tactile stimulation (striking the spider with a brush) and air movement (blowing on the spider) elicited bouncing and leaving the web, but there was no evidence that chemical stimuli from potential predators were important. Tactile stimulation elicited stronger responses than air movement. There were no evident differences in how H. pluchei responded to tactile stimulation in the laboratory and the field.     

Seasonal changes in photosystem II organisation and pigment composition in Pinus sylvestris

Conifers of the boreal zone encounter considerable combined stress of low temperature and high light during winter, when photosynthetic consumption of excitation energy is blocked. In the evergreen Pinus sylvestris L. these stresses coincided with major seasonal changes in photosystem II (PSII) organisation and pigment composition. The earliest changes occurred in September, before any freezing stress, with initial losses of chlorophyll, the D1-protein of the PSII reaction centre and of PSII light-harvesting-complex (LHC II) proteins. In October there was a transient increase in F₀, resulting from detachment of the light-harvesting antennae as reaction centres lost D1. The D1-protein content eventually decreased to 90%, reaching a minimum by December, but PSII photochemical efficiency [variable fluorescence (F_v)/maximum fluorescence (F_m)] did not reach the winter minimum until mid-February. The carotenoid composition varied seasonally with a twofold increase in lutein and the carotenoids of the xanthophyll cycle during winter, while the epoxidation state of the xanthophylls decreased from 0.9 to 0.1 from October to January. The loss of chlorophyll was complete by October and during winter much of the remaining chlorophyll was reorganised in aggregates of specific polypeptide composition, which apparently efficiently quench excitation energy through non-radiative dissipation. The timing of the autumn and winter changes indicated that xanthophyll de-epoxidation correlates with winter quenching of chlorophyll fluorescence while the drop in photochemical efficiency relates more to loss of D1-protein. In April and May recovery of the photochemistry of PSII, protein synthesis, pigment rearrangements and zeaxanthin epoxidation occurred concomitantly. Indoor recovery of photosynthesis in winter-stressed branches under favourable conditions was completed within 3 d, with rapid increases in F₀, the epoxidation state of the xanthophylls and in light-harvesting polypeptides, followed by recovery of D1-protein content and F_v/F_m, all without net increase in chlorophyll. The fall and winter reorganisation allow Pinus sylvestris to maintain a large stock of chlorophyll in a quenched, photoprotected state, allowing rapid recovery of photosynthesis in spring.Abbreviations Elips early light-induced proteins - EPS epoxidation state - F₀ instantaneous fluorescence - F_m maximum fluorescence - F_v variable fluorescence - LHC II light-harvesting complex of PSII - LiDS lithium dodecyl sulfate This research was supported by the Swedish Natural Science Research Council. We wish to thank Dr. Adrian Clarke¹ (Department of Plant Physiology, University of Umeå, Sweden) for advice on electrophoresis, valuable discussion and providing antibodies. Dr. Stefan Jansson¹ and Dr. Torill Hundal (Department for Biochemistry, University of Stockholm, Sweden) provided antibodies. Jan Karlsson¹ helped with the HPLC, Dr. Marianna Krol gave advice on green gels and Dr. Vaughan Hurry (Cooperative Research Centre for Plant Sciences, Australian National University, Canberra, Australia) provided valuable discussion.     

Measures of nematode community structure and sources of variability among and within agricultural fields

Whole nematode communities, extracted from soil samples taken from agricultural fields, were enumerated by taxonomic family and trophic group (i.e., bacterivores, fungivores, omnivores, plant-parasites, and predators) to evaluate nematode community structure as an indicator for monitoring ecological condition of soil. No differences were found in mixing treatments or methods of packing or shipping samples. However, extraction using Cobb's sifting and gravity method, followed by sucrose centrifugation, gave greater recovery of free-living nematodes than elutriation followed by sucrose centrifugation. Population means and variance of the sampled area were similar when sampled using different strategies for collecting soil samples within fieds, including several patterns, directions and repetitions of transects. Components of variation associated with ratios among the five trophic groups of nematodes and selected indices of community structure were quantified as variation among regions, among counties, among agricultural fields (2-ha area), among transects within agricultural fields, and within composite soil samples. The variance component for'within composite soil samples' was relatively large compared to the other components of variance. Variation within composite soil samples was less for maturity indices (based on life-history strategy characteristics), ratio of bacterivores to plant-parasites, sum of bacterivores and fungivores, populations of plant-parasites, and populations of bacterivores than for trophic diversity indices, populations of fungivores, populations of omnivores, populations of predators, or the ratio of fungivores to bacterivores. With a single composite sample per field, the ability to differentiate ecological condition of soils among fields within a region improved if the variance among and within fields exceeded the variance within composite samples. Given the variance components, power curves indicated that detection of a 10% change (with 0.8 power) in the ecological condition of soils within a region between two time periods would require sampling a minimum of 25 and 50 fields with one composite soil sample analyzed per field for the maturity and trophic diversity index, respectively. More than 100 fieldsper region would be required to detect temporal change in populations of individual trophic groups. Biplots of maturity indices, but not of trophic diversity or populations of individual trophic groups, identified clear differences among fields. Thus, maturity indices, which differentiated among sampling sites better and more efficiently than trophic diversity indices or measures based on populations of individual trophic groups, may be appropriate for use in a regional and/or national monitoring program.