Differential response to larval crowding of a long‐ and a short‐lived medfly biotype

Response of endophytic fruit fly species (Tephritidae) to larval crowding is a form of scramble competition that may affect important life history traits of adults, such as survival and reproduction. Recent empirical evidence demonstrates large differences in adult life history traits, especially longevity, among Mediterranean fruit fly (Ceratitis capitata; "medfly") biotypes obtained from different regions of the world. However, whether the evolution of long lifespan is associated with response to stress induced by larval crowding has not been fully elucidated. We investigated, under constant laboratory conditions, the response of a short‐ and a long‐lived medfly biotypes to stress induced by larval crowding. Survival and development of larvae and pupae and the size of resulting pupae were recorded. The lifespan and age‐specific egg production patterns of the obtained adults were recorded. Our findings reveal that increased larval density reduced immature survival (larvae and pupae) in the short‐lived biotype but had rather neutral effects on the longed‐lived one. Only larvae of the long‐lived biotype were capable of prolonging their developmental duration under the highest crowding regime to successfully pupate and emerge as adults. Response of emerging adults to larvae crowding conditions was similar in the two medfly biotypes. Those individuals emerging from high larval density regimes had reduced longevity and fecundity. Long‐lived biotype individuals, however, appeared to suffer a higher cost in longevity compared with the short‐lived one. The importance of our findings to understand the evolution of long lifespan is discussed.     

Learning Upright Standing on a Multiaxial Balance Board

Upright stance on a balance board is a skill requiring complex rearrangement of the postural control. Despite the large use of these boards in training the standing posture, a comprehensive analysis of the learning process underlying the control of these devices is lacking. In this paper learning to maintain a stable stance on a multiaxial oscillating board was studied by analyzing performance changes over short and long periods. Healthy participants were asked to keep the board orientation as horizontal as possible for 20 sec, performing two sessions of 8 trials separated by 15-min pause. Memory consolidation was tested one week later. Amplitude and variability of the oscillations around horizontal plane and area and sway path of the board displacement decreased rapidly over the first session. The performance was stable during the second session, and retained after 1 week. A similar behavior was observed in the anterior-posterior and medial-lateral directions for amplitude and variability parameters, with less stable balance in the anterior-posterior direction. Approximate entropy and mean power frequency, assessing temporal dynamics and frequency content of oscillations, changed only in the anterior-posterior direction during the retention test. Overall, the ability to stand on a balance board is rapidly acquired, and retained for long time. The asymmetric stability between anterior-posterior and medial-lateral directions replicates a structure observed in other standing stances, suggesting a possible transfer from previous postural experiences. Conversely, changes in the temporal dynamics and the frequency content could be associated with new postural strategies developed later during memory consolidation.     

Glycerolized Reticular Dermis as a New Human Acellular Dermal Matrix: An Exploratory Study

Human Acellular Dermal Matrices (HADM) are employed in various reconstructive surgery procedures as scaffolds for autologous tissue regeneration. The aim of this project was to develop a new type of HADM for clinical use, composed of glycerolized reticular dermis decellularized through incubation and tilting in Dulbecco’s Modified Eagle’s Medium (DMEM). This manufacturing method was compared with a decellularization procedure already described in the literature, based on the use of sodium hydroxide (NaOH), on samples from 28 donors. Cell viability was assessed using an MTT assay and microbiological monitoring was performed on all samples processed after each step. Two surgeons evaluated the biomechanical characteristics of grafts of increasing thickness. The effects of the different decellularization protocols were assessed by means of histological examination and immunohistochemistry, and residual DNA after decellularization was quantified using a real-time TaqMan MGB probe. Finally, we compared the results of DMEM based decellularization protocol on reticular dermis derived samples with the results of the same protocol applied on papillary dermis derived grafts. Our experimental results indicated that the use of glycerolized reticular dermis after 5 weeks of treatment with DMEM results in an HADM with good handling and biocompatibility properties.     

Home range and birth seasonality of Saguinus nigricollis graellsi in Ecuadorian Amazonia

A field study ofSaguinus nigricollis graellsi in the Cuyabeno Faunal Production Reserve, Ecuadorian Amazonia, established the characteristics of the home range and some reproductive aspects of the species. Field data were collected in two climatic seasons: dry, from December 1989 through March 1990, and rainy, from May through August 1990. Eight groups visited and/or lived in the study area during the dry season and ten during the rainy season. Group sizes ranged from two to nine individuals. Population density was estimated at 22–33 individuals per square km. The central group, which was followed intensively, had a home range which included both flooded and non-flooded forests. Terra firme forest was most used by the species. The home range of this group was reduced from 56.2 hectares (ha) in the dry season to 41.7 ha in the rainy season, probably as a result of a differential distribution of food plants between seasons. The presence of dense undergrowth where monkeys could hide to avoid predation and or a high concentration of food plants seem related to the preferential use of certain areas in the home range. The home ranges of neighboring groups overlapped considerably and peaceful temporary large groups were frequently observed. A generalized birth peak occurred in January 1990, dry season. In June 1990, rainy season, 40% of the groups exhibited a second birth peak. This reproductive bimodality of S. nigricollis graellsi indicates a high productivity of the forests at the Cuyabeno site. © 1995 Wiley-Liss, Inc.     

Histochemical demonstration of CEA in pathology of the colorectum

The evaluation of CEA serum levels and CEA tissue staining is one of the most common parameters used to help in the diagnosis and prognosis of colon-rectum disease. To this aim, an immunohistochemical demonstration of the CEA was carried out with the ABC staining system in sections of normal and diseased colon. 24 patients with polyps of the large intestine, 17 with rectocolitis, 22 with colon-rectum cancer and 11 normal subjects were studied. Results were positive in 9, 1% of the normal mucosa, 37, 5% of the polyps, 41, 2% of the rectocolitis and 100% of the carcinomas. However, the CEA in the positive reactions showed different degrees of staining and different cellular localization. From our results it would appear that the intracellular localization of this marker is connected with the degree of atypia in the histological sections. Immunohistochemical localization of the CEA could therefore be useful, above all in assessing the prognosis of colon-rectum disease.     

Association of colony variation in Serratia marcescens with the differential expression of protease and type 1 fimbriae

Abstract Using pulsed-field gel electrophoresis of chromosomal DNA and hybridization with the MEL1 probe, we determined the chromosomal locations of polymeric α-galactosidase genes in monosporic cultures of natural strains of Saccharomyces cerevisiae . An unusual phenomenon consisting of an accumulation of the MEL genes has been found in some specific Saccharomyces cerevisiae populations. Many strains possessed a new MEL gene located on chromosome I.     

Population-ethnic group specific genome variation allele frequency data: a querying and visualization journey

National/ethnic mutation databases aim to document the genetic heterogeneity in various populations and ethnic groups worldwide. We have previously reported the development and upgrade of FINDbase (www.findbase.org), a database recording causative mutations and pharmacogenomic marker allele frequencies in various populations around the globe. Although this database has recently been upgraded, we continuously try to enhance its functionality by providing more advanced visualization tools that would further assist effective data querying and comparisons. We are currently experimenting in various visualization techniques on the existing FINDbase causative mutation data collection aiming to provide a dynamic research tool for the worldwide scientific community. We have developed an interactive web-based application for population-based mutation data retrieval. It supports sophisticated data exploration allowing users to apply advanced filtering criteria upon a set of multiple views of the underlying data collection and enables browsing the relationships between individual datasets in a novel and meaningful way.     

Non-specific protein-DNA interactions control I-CreI target binding and cleavage

Homing endonucleases represent protein scaffolds that provide powerful tools for genome manipulation, as these enzymes possess a very low frequency of DNA cleavage in eukaryotic genomes due to their high specificity. The basis of protein-DNA recognition must be understood to generate tailored enzymes that target the DNA at sites of interest. Protein-DNA interaction engineering of homing endonucleases has demonstrated the potential of these approaches to create new specific instruments to target genes for inactivation or repair. Protein-DNA interface studies have been focused mostly on specific contacts between amino acid side chains and bases to redesign the binding interface. However, it has been shown that 4 bp in the central DNA sequence of the 22-bp substrate of a homing endonuclease (I-CreI), which do not show specific protein-DNA interactions, is not devoid of content information. Here, we analyze the mechanism of target discrimination in this substrate region by the I-CreI protein, determining how it can occur independently of the specific protein-DNA interactions. Our data suggest the important role of indirect readout in this substrate region, opening the possibility for a fully rational search of new target sequences, thus improving the development of redesigned enzymes for therapeutic and biotechnological applications.