Distinct population structure for co-occurring Anopheles goeldii and Anopheles triannulatus in Amazonian Brazil

To evaluate whether environmental heterogeneity contributes to the genetic heterogeneity in Anopheles triannulatus, larval habitat characteristics across the Brazilian states of Roraima and Pará and genetic sequences were examined. A comparison with Anopheles goeldii was utilised to determine whether high genetic diversity was unique to An. triannulatus. Student t test and analysis of variance found no differences in habitat characteristics between the species. Analysis of population structure of An. triannulatus and An. goeldii revealed distinct demographic histories in a largely overlapping geographic range. Cytochrome oxidase I sequence parsimony networks found geographic clustering for both species; however nuclear marker networks depicted An. triannulatus with a more complex history of fragmentation, secondary contact and recent divergence. Evidence of Pleistocene expansions suggests both species are more likely to be genetically structured by geographic and ecological barriers than demography. We hypothesise that niche partitioning is a driving force for diversity, particularly in An. triannulatus.

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene. Green lacewings are generalist predators, and the species Chrysoperla externa presents a great potential for use in biological control of agricultural pests due to its high predation and reproduction capacities, as well as its easy mass rearing in the laboratory. The adaptive success of a species is related to genetic variability, so that population genetic studies are extremely important in order to maximize success of the biological control. Thus, the present study used nuclear (Inter Simple Sequence Repeat - ISSR) and mitochondrial (Cytochrome Oxidase I - COI) molecular markers to estimate the genetic variability of 12 populations in the São Paulo State, Brazil, as well as the genetic relationships between populations. High levels of genetic diversity were observed for both markers, and the highest values of genetic diversity appear associated with municipalities that have the greatest areas of native vegetation. There was high haplotype sharing, and there was no correlation between the markers and the geographic distribution of the populations. The AMOVA indicated absence of genetic structure for the COI gene, suggesting that the sampled areas formed a single population unit. However, the great genetic differentiation among populations showed by ISSR demonstrates that these have been under differentiation after their expansion or may also reflect distinct dispersal behavior between males and females.

Parâmetros e símbolos a serem utilizados em Ressonância Magnética Nuclear

NMR is now frequently the technique of choice for determination of chemical structure in solution. Its uses also span structure in solids and mobility at the molecular level in all phases. The research literature in the subject is vast and ever-increasing. Unfortunately, many articles do not contain sufficient information for experiments to be repeated elsewhere, and there are many variations in the usage of symbols for the same physical quantity. It is the aim of the present recommendations to provide simple check-lists that will enable such problems to be minimised in a way that is consistent with general IUPAC formulation. The area of medical NMR and imaging is not specifically addressed in these recommendations, which are principally aimed at mainstream use of NMR by chemists (of all sub-disciplines) and by many physicists, biologists, material scientists and geologists etc. working with NMR.

Aplicação da espectroscopia de ressonância magnética nuclear para estudos de difusão molecular em líquidos: a técnica DOSY

Diffusion coefficients provide uniquely detailed and easily interpreted information on molecular organization and phase structure. They are quite sensitive to structural changes, and to binding and association phenomena, in particular for liquid colloidal or macromolecular systems. This paper describes the principles of diffusion measurements in liquids by pulsed magnetic field gradient spin-echo (PFG-SE) NMR spectroscopy. The important PFG-SE technique known as DOSY is presented and discussed. This is a noninvasive technique that can provide individual multicomponent translational diffusion coefficients with good precision in a few minutes, without the need for radioactive isotopic labelling.

Anestésicos locais: interação com membranas de eritrócitos de sangue humano, estudada por ressonância magnética nuclear de ¹H e 31P

The literature carries many theories about the mechanism of action of local anesthetics (LA). We can highlight those focusing the direct effect of LA on the sodium channel protein and the ones that consider the interaction of anesthetic molecules with the lipid membrane phase. The interaction between local anesthetics and human erythrocyte membranes has been studied by ¹H and 31P nuclear magnetic resonance spectroscopy. It was found that lidocaine (LDC) and benzocaine (BZC) bind to the membranes, increase the mobility of the protons of the phospholipid's acyl chains, and decrease the mobility and/or change the structure of the polar head groups. The results indicate that lidocaine molecules are inserted across the polar and liquid interface of the membrane, establishing both electrostatic (charged form) and hydrophobic (neutral form) interactions. Benzocaine locates itself a little deeper in the bilayer, between the interfacial glycerol region and the hydrophobic core. These changes in mobility or conformation of membrane lipids could affect the Na+-channel protein insertion in the bilayer, stabilizing it in the inactivated state, thus causing anesthesia.

Modeling of the Fluid-Structure Interaction in Inelastic Piping Systems

In many engineering applications, compliant piping systems conveying liquids are subjected to inelastic deformations due to severe pressure surges such as plastic tubes in modern water supply transmission lines and metallic pipings in nuclear power plants. In these cases the design of such systems may require an adequate modeling of the interactions between the fluid dynamics and the inelastic structural pipe motions. The reliability of the prediction of fluid-pipe behavior depends mainly on the adequacy of the constitutive equations employed in the analysis. In this paper it is proposed a systematic and general approach to consistently incorporate different kinds of inelastic behaviors of the pipe material in a fluid-structure interaction analysis. The main feature of the constitutive equations considered in this work is that a very simple numerical technique can be used for solving the coupled equations describing the dynamics of the fluid and pipe wall. Numerical examples concerning the analysis of polyethylene and stainless steel pipe networks are presented to illustrate the versatility of the proposed approach.

Concanavalin A-reactive nuclear matrix glycoprotein

The binding capacity of concanavalin A (Con A) to condensed euchromatin and heterochromatin was investigated in chicken erythrocyte nuclei (CEN), mouse liver cells, Zea mays mays meristematic cells and Drosophila melanogaster polytene chromosomes after 4 N HCl hydrolysis to determine whether binding was preferentially occurring in bands and heterochromatin. Dry mass (DM) variation was investigated in CEN by interference microscopy. Feulgen and Con A reactions were employed for all materials to correlate the loci of the two reactions. Quantifications and topological verifications were carried out by video image analysis (high performance cytometry). It was observed that 4 N HCl hydrolysis caused an important DM loss in CEN leaving a level corresponding to the average DNA DM content. In this material, Con A binding was restricted to the nuclear envelope, which reinforces the idea of the absence of a nuclear matrix in these cells. The other cell types exhibited a correspondence of Feulgen-positive and Con A-reactive areas. The Con A reaction was highly positive in the condensed chromatin areas and heterochromatin. This fact led us to speculate that Con A-positive proteins may play a role in the chromatin condensation mechanism, endowing this structure with physico-chemical stability towards acid hydrolysis and contributing to its rheological properties.

Probable effect of photoperiod on seasonal variation in the nuclear volume of the adrenal cortex of viscacha (Lagostomus maximus maximus)

The neuroendocrine system regulates several organic functions such as reproduction, metabolism and adaptation to the environment. This system shows seasonal changes linked to the environment. The experimental model used in the present study was Lagostomus maximus maximus (viscacha). The reproduction of males of this species is photoperiod dependent. Twenty-four adult male viscachas were captured in their habitat at different times during one year. The adrenal glands were processed for light microscopy. Serial cuts were stained with hematoxylin-eosin for the morphometric study, and 100 nuclei of each zone of the adrenal cortex were counted per animal. Data were analyzed statistically by ANOVA and the Tukey test. The cells of the glomerulosa zone are arranged in a tube-shaped structure. The fasciculata zone has large cells with central nuclei and clearly visible nucleoli and with a vacuolar cytoplasm. In the reticularis zone there are two of types of cells, one with a nucleus of fine chromatin and a clearly visible nucleolus and the other with nuclear pycnosis. Morphometric analysis showed maximum nuclear volumes during the February-March period with values of 133 ± 7.3 µm3 for the glomerulosa, 286.4 ± 14.72 µm3 for the fasciculata, and 126.3 ± 9.49 µm3 for the reticularis. Minimum nuclear volumes were observed in August with values of 88.24 ± 9.9 µm3 for the glomerulosa, 163.7 ± 7.78 µm3 for the fasciculata and 64.58 ± 4.53 µm3 for the reticularis. The short winter photoperiod to which viscacha is subjected could inhibit the adrenal cortex through a melatonin increase which reduces the nuclear volume as well as the cellular activity.

Glutamate receptors as seen by light: spectroscopic studies of structure-function relationships

Ionotropic glutamate receptors are major excitatory receptors in the central nervous system and also have a far reaching influence in other areas of the body. Their modular nature has allowed for the isolation of the ligand-binding domain and for subsequent structural studies using a variety of spectroscopic techniques. This review will discuss the role of specific ligand:protein interactions in mediating activation in the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid subtype of glutamate receptors as established by various spectroscopic investigations of the GluR2 and GluR4 subunits of this receptor. Specifically, this review will provide an introduction to the insight gained from X-ray crystallography and nuclear magnetic resonance investigations and then go on to focus on studies utilizing vibrational spectroscopy and fluorescence resonance energy transfer to study the behavior of the isolated ligand-binding domain in solution and discuss the importance of specific ligand:protein interactions in the mechanism of receptor activation.