Diurnal Behavioral and Metabolic Patterns in Chronic Malnourished Rats

The temporal organization of behavioral patterns and metabolic activity was assessed in chronic low protein malnourished rats and their nutritional controls at 60 days of age. Spontaneous activity was video-recorded during 3 days for 10 min every hour and the frequency of exploration, grooming and ingestive behaviors was obtained, their basal metabolic rate was measured during 5 min every hour for one 24 h cycle. Rats of both nutritional groups showed a clear diurnal rhythmicity in all behavioral patterns, characterized by an increase of activity during the dark phase and a decrease during the light phase. Effects of malnutrition were selective and produced mainly a general decrease of the mean value and amplitude of the rhythm of ingestive behavior, as well as a bimodal pattern and rhythmic components of 12, 24 and 30 h according to autocorrelation and cosinor analysis. In both groups, the metabolic rate showed a bimodal diurnal rhythm, which fitted significantly to a 12 h period model and was not affected in malnourished rats. These data provide evidence that the circadian system is highly resistant to malnutrition. In malnourished rats rhythmicity of ingestive behavior was specifically affected, probably because the relation between metabolic processes and ingestive behaviors may be enhanced as a compensatory mechanism aimed to counteract the deficient diet composition.     

Helical flows and asymmetry of blood jet in dilated ascending aorta with normally functioning bicuspid valve

Bicuspid aortic valve (BAV) is associated with aortic dilatation and aneurysm. Several studies evidenced an eccentric systolic flow in ascending aorta associated with increased wall shear stresses (WSS) and the occurrence of an helical systolic flow. This study seeks to elucidate the connections between jet asymmetry and helical flow in patients with normally functioning BAV and dilated ascending aorta. We performed a computational parametric study by varying, for a patient-specific geometry, the valve area and the flow rate entering the aorta and drawing also a tricuspid valve (TAV). We considered also phase-contrast magnetic resonance imaging of four BAV and TAV patients. Measurement of normalized flow asymmetry index, systolic WSS and of a new index (positive helix fraction, PHF) quantifying the presence of a single a single helical flow were performed. In our computation, BAV cases featured higher values of all indices with respect to TAV in both numerical and imaged-based results. Moreover, all indices increased with decreasing valve area and/or with increasing flow rate. This allowed to separate the BAV and TAV cases with respect to the jet asymmetry, WSS localization and helical flow. Interestingly, these results were obtained without modeling the leaflets.     

Comparing body and otolith shape for stock discrimination of Pacific sardine,Sardinops sagax Jenyns, 1842

Stock discrimination in fishes is important for fisheries management. Morphometric analysis has been a viable approach when different structures (overall body, otoliths, and scales) are used. However, in cases where a single source of information may already differentiate among stocks, different conclusions may be obtained when using different sources of information. These have to be considered because they could lead to different management plans. Using geometric morphometrics, data was analyzed regarding the body and otolith shape of the Pacific sardine Sardinops sagax Jenyns, 1842 collected off the west coast of Baja California Peninsula, Mexico. Results confirm seasonal differences in body shape and otolith shape in stocks previously associated with sea surface temperature. Although both measures resulted in compatible conclusions, the shape of the body discriminated groups more appropriately; the data indicate that differential resolution could be thus obtained, depending on the source of the data. If possible, the application of more than one source of information is suggested in comparable cases because this would detect the extent of stock isolation with greater certainty.     

Dichroic behavior of the absorbance signals from dyes NK2367 and WW375 in skeletal muscle fibers

Absorbance signals were recorded from voltage-clamped single muscle fibers stained with the nonpenetrating potentiometric dyes NK2367 and WW375 and illuminated with quasimonochromatic light from 560 to 800 nm, linearly polarized either parallel (0 degree) or perpendicular (90 degrees) to the fiber long axis. The signals from both dyes depend strongly on the incident polarization. At any wavelength and/or polarization condition, the total absorbance signal is a superposition of the same two signal components previously identified with unpolarized light (Heiny, J. A., and J. Vergara, 1982, J. Gen. Physiol., 80:203)--namely, a fast step signal from the voltage-clamped surface membrane and a signal reflecting the slower T-system potential changes. The 0 degree and 90 degrees spectra of both membranes have similar positive and negative absorbance peaks (720 and 670 nm, respectively, for dye NK2367; 740 and 700 nm for dye WW375); in addition, they have the same dichroic maxima (670 for NK2367; 700 for WW375). However, for the surface membrane, the 0 degrees spectra are everywhere more positive than the 90 degrees spectra, whereas the reverse is true for the T-system, which results in a dichroism of opposite sign for the two membranes. These spectral characteristics were analyzed using a general model for the potential-dependent response of an absorbing dye (Tasaki, I., and A. Warashina, 1976, Photochem. Photobiol., 24:191), which takes into account both the dye response and the membrane geometries. They are consistent with the proposal that the dye responds via a common mechanism in both membranes that consists of a dye reorientation and a change in the absorption maxima.     

The use of metallochromic Ca indicators in skeletal muscle

Absorbance signals recorded with metallochromic indicators in skeletal muscle fibers show rapid time courses that probably closely track the fast kinetic process of Ca++ release and retrapping by the sarcoplasmic reticulum. However, the formation of more than one complex in cuvette calibrations, both for Arsenazo III (ArIII) and Antipyrylazo III (ApIII), suggest that care needs to be taken in the deconvolution of in vivo absorbance signals. Since the kinetic rate constants have not yet been obtained for these probes, attempts to deconvolute absorbance signals should be considered approximate. The evidence suggesting that more than one complex is formed during a skeletal muscle transient with ArIII is more compelling than for the case of ApIII. The differences between the ArIII and ApIII signals may not be readily explained assuming 1:1 dye:Ca complexation and kinetic differences between the probes. Competition for Ca++ with cell Ca buffers and/or multiple complex formation by at least one of these probes needs to be invoked. Based on a simple model to simulate the behavior of the Ca signals in muscle, it may be suggested that an ApIII-like probe would more closely track pCa changes in the fiber than would an ArIII-like probe, which would show more interference with intracellular buffers; an even higher affinity probe would tend to sense the total release of Ca by the SR.     

Dichloromethane as an economic alternative to chloroform in the extraction of DNA from plant tissues

Processing of large numbers smaples of plant tissue samples for molecular mapping and gene tagging requires methods that are quick, simple, and cheap, and that eventually can be automated. Organic solvents used for DNA extraction can represent a significant proportion of the overall cost. In this study we examined dichloromethane as a replacement for chloroform to be used in combination with phenol.     

Molecular and morphometric systematics of Diapterus (Perciformes,Gerreidae)

The fish belonging to Gerreidae are common representatives of the coastal ichthyofauna of the tropics and subtropics of the world. The genus Diapterus has a neotropical distribution and currently includes four species: two in the Atlantic Ocean [Irish mojarra D. auratus Ranzani 1842 and rhombic mojarra D. rhombeus (Cuvier 1829)] and two in the Pacific Ocean [short‐beaked mojarra D. brevirostris (Sauvage 1879) and golden mojarra D. aureolus (Jordan & Gilbert 1882)]. This genus has uncertain taxonomy based on the remarkable and dissimilar morphology of D. aureolus. We evaluated the taxonomy and phylogeny of Diapterus with statistical (canonical discriminant analysis) and phylogenetic analyses (maximum parsimony, maximum likelihood and Bayesian inference) of geometric morphometric data (relative warps) and molecular data (12Sr RNA, 16Sr RNA, COI and RAG1 sequences). Our results indicate that the genus Diapterus as we currently conceive it is a polyphyletic group: [(Gerres cinereus – Eucinostomus spp. (D. aureolus – (Eugerres spp. (D. auratus – (D. brevirostris – D. rhombeus)))))]. Therefore, a taxonomic rearrangement is needed. To preserve the monophyly of the group, our proposal is to remove D. aureolus and place it in a new monotypic genus. A neotype is designated for D. aureolus as well as an artificial identification key for the genera and the species treated in this article.