Development of a monoclonal antibody to detect predation of the sweetpotato whitefly,Bemisia tabaci

We have developed an enzyme-linked immunosorbent assay (ELISA) for detection of whitefly antigen in the guts of predaceous arthropods based on a monoclonal antibody (MAb) produced in response toBemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) egg antigen. We observed positive antigen-antibody reactions with the egg and the adult female stages of certain whitefly species and not with others. This MAb did not cross-react with any of the whitefly nymphs or adult males we tested. Moreover, this MAb did not cross-react with the various life stages of other insect species we examined. This immunologically-based technique to identify whitefly egg facilitates examinations of predator gut contents in the field. Such a specific and sensitive whitefly egg immunoassay will expedite the characterization of theB. tabaci predator complex in the southwestern United States.     

The Emerging Role of Copeptin

Direct measurement of the nonapeptide vasopressin has been limited by analyte instability ex vivo and in vivo rapid degradation, low serum concentrations requiring a sensitive assay and inherent secretory pulsatility. Copeptin is a 39 amino acid glycopeptide cleavage product of vasopressin synthesis with high stability, providing a marker of vasopressin secretion. Copeptin measurement has applications in diagnosis of diabetes insipidus and other diseases with altered vasopressin secretion. This review summarises our current understanding of serum copeptin measurement in diabetes insipidus and possible future applications of copeptin assays. As vasopressin is a stress hormone, there is emerging evidence on the use of copeptin for diagnosis and prognostication of disorders such as syndrome of inappropriate anti-diuretic hormone secretion, diabetes mellitus, critical illness, stroke, cardiovascular disease, respiratory disease, renal disease and thermal stress. Copeptin concentration measurement is likely to improve the diagnostic reliability of diabetes insipidus and, as a marker of stress, may have diagnostic or prognostic utility in specific clinical circumstances. Further studies are needed to determine if goal-directed therapy using plasma copeptin concentrations may improve patient outcomes.     

ANTHROPOMETRIC DETERMINANTS OF ROWING ERGOMETER PERFORMANCE IN PHYSICALLY INACTIVE COLLEGIATE FEMALES

The aim of the study was to evaluate anthropometric characteristics as determinants of 500 m rowing ergometer performance in physically inactive collegiate females. In this cross-sectional study, which included 196 collegiate females aged 19-23 years not participating in regular physical activities, body mass (BM), body height (BH), length of upper limbs (LA), length of lower limbs (LL), body mass index (BMI), slenderness index (SI), and the Choszcz-Podstawski index (CPI) were measured and a stepwise multiple regression analysis was performed. Participants performed 500 m maximal effort on a Concept II rowing ergometer. BM, BH, LA, LL, and the BMI, SI and CPI indices were found to be statistically significant determinants of 500 m performance. The best results (T) were achieved by females whose BH ranged from 170 to 180 cm, with LA and LL ranging from 75 to 80 cm and 85 to 90 cm, respectively. The best fitting statistical model was identified as: T = 11.6793 L_R – 0.1130 L_R² – 0.0589 L_N² + 29.2157 CPI² + 0.1370 LR·LN - 2.6926 LR·CPI – 211.7796. This study supports a need for additional studies focusing on understanding the importance of anthropometric differences in rowing ergometer performance, which could lead to establishing a better quality reference for evaluation of cardiorespiratory fitness tested using a rowing ergometer in collegiate females.     

Development and application of monoclonal antibodies for the detection of white spot syndrome virus of penaeid shrimp.

Monoclonal antibodies (MAbs) were produced against white spot syndrome virus (WSSV) of penaeid shrimp. The virus isolate used for immunization was obtained from China in 1994 and was passaged in Penaeus vannamei. The 4 hybridomas selected for characterization all produced MAbs that reacted with the 28 kD structural protein by Western blot analysis. The MAbs tested in dot-immunoblot assays were capable of detecting the virus in hemolymph samples collected from moribund shrimp during an experimentally induced WSSV infection. Two of the MAbs were chosen for development of serological detection methods for WSSV. The 2 MAbs detected WSSV infections in fresh tissue impression smears using a fluorescent antibody for final detection. A rapid immunohistochemical method using the MAbs on Davidson's fixed tissue sections identified WSSV-infected cells and tissues in a pattern similar to that seen with digoxigenin-labeled WSSV-specific gene probes. A whole mount assay of pieces of fixed tissue without paraffin embedding and sectioning was also successfully used for detecting the virus. None of the MAbs reacted with hemolymph from specific pathogen-free shrimp or from shrimp infected with infectious hypodermal and hematopoietic necrosis virus, yellow head virus or Taura syndrome virus. In Western blot analysis, the 2 MAbs did not detect any serological differences among WSSV isolates from China, Thailand, India, Texas, South Carolina or Panama. Additionally, the MAbs did not detect a serological difference between WSSV isolated from penaeid shrimp and WSSV isolated from freshwater crayfish.     

Evolution at the tip and base of the X chromosome in an African population of Drosophila melanogaster

Hitchhiking effects of advantageous mutations have been invoked to explain reduced polymorphism in regions of low crossing-over in Drosophila. Besides reducing DNA heterozygosity, hitchhiking effects should produce strong linkage disequilibrium and a frequency spectrum skewed toward an excess of rare polymorphisms (compared to the neutral expectation). We measured DNA polymorphism in a Zimbabwe population of D. melanogaster at three loci, yellow, achaete, and suppressor of forked, located in regions of reduced crossing-over. Similar to previously published surveys of these genomic regions in other populations, we observed low levels of nucleotide variability. However, the frequency spectrum was compatible with a neutral model, and there was abundant evidence for recombination in the history of the yellow and ac genes. Thus, some aspects of the data cannot be accounted for by a simple hitchhiking model. An alternative hypothesis, background selection, might be compatible with the observed patterns of linkage disequilibrium and the frequency spectrum. However, this model cannot account for the observed reduction in nucleotide heterozygosity. Thus, there is currently no satisfactory theoretical model for the data from the tip and base of the X chromosome in D. melanogaster.      

Short chain oligogalacturonides induce ethylene production and expression of the gene encoding aminocyclopropane 1-carboxylic acid oxidase in tomato plants

Oligogalacturonic acids (OGAs), derived from plant cell wall pectin, have been implicated in a number of signal transduction pathways involved in growth, development and defense responses of higher plants. This study investigates the size range of OGAs capable of inducing ethylene synthesis in tomato plants, and demonstrates that in contrast with many other effects, only short chain OGAs are active. Oligomers across a range of DP from 2-15 were separated and purified to homogeneity by QAE-Sephadex anion exchange chromatography using a novel elution system. The OGAs were applied to tomato plants and assayed for their ability to induce ethylene gas release and changes in steady state levels of mRNA encoding the ethylene forming enzyme aminocyclopropane-1-carboxylic acid oxidase (ACO). The study demonstrated that only OGAs in the size range of DP4-6 were active both in eliciting ACO expression and in the production of ethylene.      

A change in twist of actin provides the force for the extension of the acrosomal process in limulus sperm: the false-discharge reaction

One of the most spectacular motions is the generation of the acrosomal process in the limulus sperm. On contact with the egg, the sperm generates a 60-mum-long process that literally drills its way through the jelly surrounding the egg. This irresversible reaction takes only a few seconds. We suggested earlier that this motion is driven by a change in twist of the actin filaments comprising the acrosomal process. In this paper we analyze the so-called false discharge, a reversible reaction, in which the acrosomal filament bundle extends laterally from the base of the sperm and not anteriorly from the apex. Unlike the true discharge, which is straight, the false discharge is helical. Before extension, the filament bundle is coiled about the base of the sperm. In the coil, the bundle is not smoothly bent but consists of arms (straight segments) and elbows (corners) so that the coil looks like a 14-sided polygon. The extension of the false discharge works as follows: starting at the base of the bundle, the filaments change their twist which concomitantly changes the orientations of the elbows relative to each other; that is, in the coil, the elbows all like in a common plane, but after the change in twist, the plane of each elbow is rotated to be perpendicular to that of its neighbors. This change transforms the bundle from a compact coil into an extended left- handed helix. Because the basal end of the bundle is unconstrained, the extension is lateral. The true discharge works the same way but starts at the apical end of the bundle. The apical end, however, is constrained by its passage through the nuclear canal, which directs the extention anteriorly. Unlike the false discharge, during the true discharge the elbows are melted out, making the reaction irreversible. This study shows that rapid movement can be regenerated by actin without myosin and gives us insight into the molecular mechanism.