A technique for microsecond heating and cooling of a thin (submicron) biological sample

Temperature excursions of short duration are useful in exploring the effects of stress on biological systems. Stress will affect the conformation of biological molecules such as proteins, which will lead to an effect on their function. The feasibility of generating such temperature excursions is demonstrated by solving the heat diffusion equation for an aqueous layer on a silicon wafer. The silicon is rapidly heated by a laser pulse and also acts as a heat sink to quench the temperature rise. An oxide layer was used to limit the maximum temperature attained by the sample. We show that exposures above a 50 degrees C benchmark can be confined to times less than 5 micros.     

Role of sperm surface arylsulfatase A in mouse sperm-zona pellucida binding

We have previously described the zonae pellucidae (ZP) binding ability of a pig sperm surface protein, P68. Our recent results on peptide sequencing of 3 P68 tryptic peptides and molecular cloning of pig testis arylsulfatase A (AS-A) revealed the identity of P68 as AS-A. In this report, we demonstrate the presence of AS-A on the mouse sperm surface and its role in ZP binding. Using anti-AS-A antibody, we have shown by immunoblotting that AS-A was present in a Triton X-100 extract of mouse sperm. The presence of AS-A on the sperm plasma membrane was conclusively demonstrated by indirect immunofluorescence, immunogold electron microscopy, and AS-A's desulfation activity on live mouse sperm. The AS-A remained on the head surface of in vivo capacitated sperm, as revealed by positive immunofluorescent staining of oviductal/uterine sperm. Significantly, the role of mouse sperm surface AS-A on ZP binding was demonstrated by dose-dependent decreases of sperm-ZP binding on sperm pretreatment with anti-AS-A IgG/Fab. Furthermore, Alexa-430 conjugated AS-A bound to mouse ZP of unfertilized eggs but not to fertilized ones, and this level of binding increased and approached saturation with increasing Alexa-430 AS-A concentrations. Moreover, in vivo fertilization was markedly decreased when mouse sperm pretreated with anti-AS-A IgG were artificially inseminated into females. All of these results designated a new function for AS-A in mouse gamete interaction.     

Alpha 4 integrin increases anoikis of human osteosarcoma cells

Cell motility, growth, and proliferation are regulated by adhesion to the extracellular matrix. Detachment of adherent cells from extracellular matrix results in induction of apoptosis ("anoikis"). Transformed cells often show an anchorage-independent growth that enables them to acquire a motile, invasive phenotype. This phenotype has been associated with the altered expression and function of the integrin family of transmembrane proteins that mediate cell adhesion to the extracellular matrix. Although alpha4 integrin is normally expressed on leukocyte subpopulations, a number of metastatic melanomas and sarcomas express it as well. In this study, we demonstrated the expression of alpha4 integrins on the human osteosarcoma cell line SAOS and on metastatic osteosarcoma lesions from the lung and pericardium. We further demonstrated that alpha4 integrin is coupled to the beta1 subunit by biochemical analysis and by using a mAb directed against a combinatorial epitope unique to the alpha4beta1 molecule. SAOS cells undergo anoikis when adherence is denied. Anoikis involved the activation of caspase 3 and the release of cytochrome c from mitochondria. Treatment of non-adherent SAOS with an anti-alpha4 mAb increased anoikis while anti-beta1 integrin mAbs did not alter anoikis, thus indicating a novel function for the alpha4 subunit in the control of cell death. Since integrins can control cell migration, proliferation, and apoptosis these results demonstrate a potential role for alpha4 integrin during multiple aspects of osteosarcoma metastasis.     

Interrelationship between ectoparasites and wild rodents from northeastern Buenos Aires Province,Argentina

Infestation parameters and indices of mites, ticks and fleas associated with wild rodents from northeastern Buenos Aires Province, Argentina, were studied. Host species similarity was also analyzed in relation to their ectoparasites. Fifty-five rodents were captured from January 2000 to March 2001. In total, 1,022 ectoparasites were collected and three ectoparasite-host associations were new records. However, this is the first study on Craneopsylla minerva wolffhuegeli infesting parameters. Ectoparasite total mean abundance and total prevalence were higher in Holochilus brasiliensis (MA = 47.7; P = 100%) and Scapteromys aquaticus (MA = 25.4; P = 95.4%), meanwhile specific richness and diversity were higher in Oligoryzomys flavescens (S = 6; H = 1.3) and Akodon azarae (S = 4; H = 1.0). On the other hand, the only individual of Calomys laucha was not parasited. S. aquaticus-H. brasiliensis, which preferred similar microhabitats, shared the same ectoparasite species (Css = 100). Whereas, A. azarae, which was mostly associated with grassland, showed the highest difference with the other hosts (Css < 0.4). Considering every ectoparasite species, H. brasiliensis showed the highest mean abundance, prevalence and preference. The results suggest that the particular characteristics of this rodent would give it better possibilities not only of being infested by ectoparasites, but also of transmitting them to its progeny.     

New cases of Diphyllobothrium pacificum (Nybelin, 1931) Margolis, 1956 human infection in North of Chile,probably related with El Niño phenomenon, 1975-2000

The effect of El Ni?o/ENSO on terrestrial atmosphere appears to be extremely clear. However there are outstanding evidences showing its effect on humans and their activities. In fact, prevalence of some parasitic infections have increased during El Ni?o phenomenon. The reasons for that are the migrations of sylvatic mammals, fishes and birds as well as by environmental contamination. In this report, we show evidence respect of new cases of human infection by Diphyllobothrium pacificum clearly associated with a cyclic manifestation of El Ni?o in the Chilean Pacific coast during 1975-2000.     

The Retina of Crayfish Procambarus clarkii During Development Shows Serotonin and Tryptophan Hydroxylase-like Immunoreactivity Daily Changes

The aim of this work was to investigate possible changes in serotonin (5-HT) and tryptophan hydroxylase (TPH)-like immunoreactivity related to time of day in Procambarus clarkii retina during the first developmental stages. Forty-five animals from postembryonic instars (PO1, PO2) to juvenile stage were kept under LD 12:12 cycles. All animals were anesthetized and decapitated at three times of day, 08:00, 15:00 and 20:00 h. Isolated eyestalks were processed by immunohistochemical methods. The 5-HT-like immunoreactive area of retina was measured using computer-based image analysis. Results indicated 5-HT-like immunoreactive differences among the three crayfish instars studied. In PO1 animals, ANOVA revealed no significant differences in 5-HT-like immunoreactivity in the retina at different times of day. PO2 instars as well as juvenile instars, showed statistically significant retinal 5-HT-like immunoreactivity changes related to time of day. Preliminary results indicated that TPH-like immunoreactivity was located only in the tapetal and retinal cells, and it was related to time of day. These changes suggest a diurnal cyclic regulation in the synthesis of 5-HT in the retina.     

High-Andean vegetation and environmental gradients in northwestern Patagonia,Argentina

Abstract. We analysed the heterogeneity of high-elevation vegetation on three mountains along a west-east transect at 41 °S lat. in the Andes of northwestern Patagonia, Argentina. In this area, high-Andean vegetation occurs as islands on mountain tops above Nothofagus pumilio forests ? with the timberline at ca. 1700 m a.s.l. We recorded floristic, topographic and substrate data in 166 sites stratified according to longitude, altitude, slope and aspect. Vegetation data were classified with TWINSPAN and ordinated with Detrended Correspondence Analysis. The relationship between environmental and floristic variation was analysed using Canonical Correspondence Analysis. In order of importance, geographical longitude, altitude and aspect were the major determinants of vegetation variation, whereas substrate texture and slope appeared less important. The combination of these factors resulted in two main vegetation gradients. The first gradient is related to a moisture availability gradient, primarily determined by longitude and secondarily to variation in wind exposure (east vs. west aspect). The second vegetation gradient is related to variation in temperature, primarily determined by altitude, and secondarily by variation in insolation related to the contrast between north and south aspects. The four communities obtained with TWINSPAN are therefore associated with four characteristic habitat types: moist-cold, moist-warm, dry-cold and dry-warm. The community of warm and dry environments is the richest and has elements in common with dry steppe communities situated at lower elevations to the east, while the vegetation of the cold-moist habitat type has unique elements that are typical of the southern Andes. Although current climatic factors appear to be the major determinants of high-Andean vegetation gradients, historical events of Pleistocene times probably also affected the vegetation patterns we see today.     

Increased glycated calmodulin in the submandibular salivary glands of streptozotocin‐induced diabetic rats

Non‐enzymatic glycosylation, a post translational protein modification may be implicated in the diabetes complications. Calmodulin is an important calcium binding protein that complexed with Ca²⁺ may be implicated in salivary gland secretory process. Glycated calmodulin has shown to be less effective in binding calcium. The aim of this study was to determine whether the concentration of glycated‐calmodulin may be elevated in the submandibular salivary glands of streptozotocin‐induced diabetic rats. Diabetes was induced by an intraperitoneal injection of spreptozotocin, and hyperglycemia was confirmed 72 h after injection using a glucosimeter. Thirty days after the induction of diabetes, submandibular salivary glands were used for the analysis of glycated and non‐glycated calmodulin, using a glycogel B columns for separation. Glycated and non‐glycated calmodulin were assayed by an enzymatic method and by ELISA. The overall concentration of CaM (non‐glycated + glycated) in induced diabetic rats was significantly lower than in controls (p < 0.05). The concentration of non‐glycated CaM in controls was significantly higher than in experimental group (p < 0.05), while the concentration of glycated calmodulin between these groups was statistically similar (p > 0.05). Copyright © 2009 John Wiley & Sons, Ltd.