Altered Neurotrophin mRNA Levels in Peripheral Nerve and Skeletal Muscle of Experimentally Diabetic Rats

Abstract: The levels of neurotrophin mRNA in sensory ganglia, sciatic nerve, and skeletal muscle were measured in the streptozotocin-diabetic rat using northern blotting. Periods of diabetes of 4, 6, and 12 weeks significantly elevated brain-derived neurotrophic factor (BDNF) mRNA levels in soleus muscle compared with age-matched controls, the increase being highest at 6 weeks. At all time periods studied, the levels of nerve growth factor (NGF) mRNA in soleus muscle were decreased by 21–47%. Following 12 weeks of diabetes, BDNF mRNA levels were increased approximately two-to threefold in L4 and L5 dorsal root ganglia (DRG), and in sciatic nerve, NGF mRNA levels were raised 1.65-fold. Intensive insulin treatment of diabetic rats for the final 4 weeks of the 12-week period of diabetes reversed the up-regulation of BDNF mRNA in DRG and muscle and NGF mRNA in sciatic nerve. All diabetes-induced changes in neurotrophin mRNA were not paralleled by similar alterations in the levels of β-actin mRNA in muscle and nerve, or of GAP-43 mRNA in DRG and nerve. It is proposed that the up-regulation of neurotrophin mRNA is an endogenous protective and/or repair mechanism induced by insult and, as such, appears as an early marker of peripheral nerve and muscle damage in experimental diabetes.     

Using higher taxa as surrogates of species-level data in three Portuguese protected areas: a case study on Spheciformes (Hymenoptera)

Protected areas are the focus of most conservation efforts worldwide. Despite vast amount of investment in protected areas, biodiversity loss continues. This has led to increasing efforts to develop measures to assess the effectiveness of protected areas. The reliability of these measures depends on the quality of the information collected. However, because the resources available for the collection of information are limited, several strategies have been developed to reduce the resources necessary. In this study the combination of two resource reduction approaches—bioindicator and higher-taxa—is proposed. Spheciformes have been found to be useful as biodiversity, ecological and environmental indicators. Identification to the species level is usually very costly, but the use of genus-level information has been suggested. Tribe- and genus-level data for Spheciformes were assessed for their ability to predict the number of species independently of other variables—sampling area, geographic location, vegetation type, disturbance regime, and sampling effort—at three Portuguese protected areas. Tribe and genus-level data were found to be good indicators, with genus being the more reliable taxonomic level. Sampling effort was the only external variable that affected the relationship between species and higher-taxa richness. Genus-level data were also found to be useful for ranking sites according to richness or composition, and for determining richness-based and rarity-based complementary sets of sites for conservation. Using genus richness as a surrogate for species richness seems a promising approach for monitoring and contributing to the establishment of protected areas in Portugal and the entire Mediterranean region.     

N-cadherin is required for the polarized cell behaviors that drive neurulation in the zebrafish

Through the direct analysis of cell behaviors, we address the mechanisms underlying anterior neural tube morphogenesis in the zebrafish and the role of the cell adhesion molecule N-cadherin (N-cad) in this process. We demonstrate that although the mode of neurulation differs at the morphological level between amphibians and teleosts, the underlying cellular mechanisms are conserved. Contrary to previous reports, the zebrafish neural plate is a multi-layered structure, composed of deep and superficial cells that converge medially while undergoing radial intercalation, to form a single cell-layered neural tube. Time-lapse recording of individual cell behaviors reveals that cells are polarized along the mediolateral axis and exhibit protrusive activity. In N-cad mutants, both convergence and intercalation are blocked. Moreover, although N-cad-depleted cells are not defective in their ability to form protrusions, they are unable to maintain them stably. Taken together, these studies uncover key cellular mechanisms underlying neural tube morphogenesis in teleosts, and reveal a role for cadherins in promoting the polarized cell behaviors that underlie cellular rearrangements and shape the vertebrate embryo.     

Functional response of <Emphasis Type="Italic">Pteromalus cerealellae</Emphasis> (Hymenoptera: Pteromalidae) on the cowpea weevil, <Emphasis Type="Italic">Callosbruchus maculatus</Emphasis> (Coleoptera: Bruchidae), and interaction between parasitism and cowpea varietal susceptibility

Laboratory studies were carried out to determine the functional response of the parasitoid, Pteromalus cerealellae (Boucek) to cowpea weevil, Callosobruchus maculatus (F.) hosts, and the relationship between parasitism and cowpea variety susceptibility to the weevil. The attack response of P. cerealella to weevil larvae was best described by a type III functional response using an egg limitation model. The mean attack rate (a) of the parasitoid was estimated as 1.7 and the upper limit of the response was 24 weevil larvae per individual parasitoid within a 48-h period. The results also showed that cowpea varieties resistant to weevil infestation supported fewer weevil progeny and facilitated a greater suppression of the weevil by the parasitoid. The parasitoid progeny index, a measure that compares the number of the parasitoid progeny to the number of the beetle progeny was higher in cowpea weevil resistant varieties than in susceptible varieties. Additionally, the presence of P. cerealellae resulted in reduced weight losses of cowpea caused by the weevil infestation in both susceptible and resistant varieties.     

A simple micro-growth assay for enumerating bacteria

A simple method for nonspecific determination of bacteria concentrations in a variety of liquid samples was developed. The assay was based on the time required for a sample grown in liquid media to reach a threshold turbidity. Samples were combined with media in a covered 96-well microwell plate and the turbidity was monitored in real time as the bacteria grew in a temperature-controlled plate reader. A significant problem with growth in microwells was condensation on the cover, which prevented accurate turbidity measurement. This problem was overcome by coating the cover with a small amount of surface-active agent. Salmonella and E. coli concentrations could be determined with a relative error of approximately 20% at levels from 10 to 10(6) cells/ml (eight replicates). An assay of 10 samples with standards required 10 min to set up and 20 min for data processing using a computer spreadsheet program. Growth time at 37 degrees C ranged from 4 h for samples at 10(7) cells/ml to 16 h for samples at 10 cells/ml.     

Analysis of the genomic organisation of a small chromosome of Leishmania braziliensis M2903 reveals two genes encoding GTP-binding proteins, one of which belongs to a new G-protein family and is an antigen

Leishmania braziliensis M2903 contains a highly amplified small chromosome. This work is aimed at resolving its structural organization and determining whether this unusual chromosome contains specific genes encoding proteins with important functions in disease pathology or drug resistance. Our results show that the M2903 250-kb small chromosome contains LD1 sequences and has an inverted repeat structure. The LD1 sequences and two cDNAs (cDNA2 and cDNA53) were mapped on a cosmid contig, and the two cDNAs and the corresponding genomic fragments from the small chromosome were sequenced. The gene encoding cDNA2 predicts a putative GTP-binding protein with homology to other GTP-binding proteins only in the G-1 domain region; however, four other conserved motifs can be recognized. Sequence similarity to cDNA53 is located in at least five chromosomes, and its small chromosome copy is a pseudogene. An open reading frame downstream of the cDNA53 pseudogene predicts another GTP-binding protein that belongs to a new G-protein family with an unusual conserved GTP-binding domain and a newly characterized conserved sequence motif. A portion of this GTP-binding protein gene was studied previously in L. aethiopica as a recombinant antigen that reacts with human antibodies.