Transduction of penicillinase production in Staphylococcus epidermidis and nature of the genetic determinant.

Four strains of Staphylococcus epidermidis from clinical sources were capable of serving as donors for the transduction of either penicillinase production, ethidium bromide resistance, or tetracycline resistance. Three typing phages served as transducing phages and, depending upon the combination of transducing phage, donor strain, and recipient strain, the rates of transduction ranged between 10(-5) and 10(-9). In one strain, cotransduction of penicillinase production and ethidium bromide resistance was observed. Although ultraviolet irradiation kinetics indicated that both the tetracycline resistance and the penicillin resistance determinants were located on plasmids, only resistance to tetracycline could be eliminated by growth in the presence of curing agents or at elevated temperature. However, evidence was obtained by agarose gel electrophoretic studies that both the tetracycline resistance and the penicillin resistance determinants are located on separate plasmids in this organism.     

Regulatory effects of exogenous branched-chain amino acids in Nicotiana plumbaginifolia cell suspension cultures

Nicotiana plumbaginifolia suspension cultured cells were grown on medium supplemented with valine, leucine and isoleucine, singly or in combination. The effects of the three branched-chain amino acids on cell growth rate and on the activity of acetohydroxyacid synthase (AHAS), the first enzyme (and the main regulative site) of their biosynthetic pathway, were studied. Results showed that valine and leucine, at concentrations ranging from 10^–4 to 10^–3 M, inhibit growth, and at higher doses (from 10^–2 to 10^–1 M) AHAS activity. Growth, but not AHAS activity, was affected also by isoleucine. The addition of ammonium succinate to the culture medium, in order to counteract a possible general inhibitory effect of these compounds on nitrogen metabolism, relieved only partially their cytotoxicity. Feeding cells with equimolar mixtures of the three amino acids resulted in a minor but reproducible decrease in AHAS level, which was proportional to the dose. A similar result was obtained also on N. plumbaginifolia seedlings, suggesting that in this species a modulation of enzyme level could play a role in controlling the flow of metabolites through the pathway.Abbreviations AHAS acetohydroxyacid synthase - BCAA branched-chain amino acids - FAD flavin adenine dinucleotide - GS glutamine synthetase - TPP thiamine pyrophosphate     

Caroteno-protein complexes in Axinella verrucosa (Porifera: Demospongae)

Carotenoproteins are common to a wide variety of animals, most notably invertebrates although other animal groups have been shown to have these complexes as well. In a previous paper alpha-carotene, renieratene, isorenieratene and an unknown isomer of renieratene were isolated, but at present nothing is known about nature of the carotenoid-protein complexes in A. verrucosa. In this paper we report our results about a carotenoid-protein complex extracted by TRITON X-100 and purified by Sephadex G 200 Fine and DEAE-Sephacel chromatography. This carotenoprotein had a molecular weight of ca. 390,000 dalton (Gel electrophoresis). SDS PAGE plate showed only a single polypeptide chain of ca. 50,000 dalton. The proteic band separated by PAGE plate electrophoresis showed the presence of lipids and glycids when stained respectively by Sudan Black B and by Schiff's reagent. The extract obtained without TRITON X-100 showed the presence of a similar carotenoid-protein complex, but because of the low proteic concentration this result should be confirmed.     

Three dimensional visualisation of human facial exposure to solar ultraviolet.

A three dimensional computer model of the human face has been developed to represent solar ultraviolet exposures recorded by dosimeter measurements on a manikin headform under low cloud conditions and various solar zenith angles. Additionally, polysulfone dosimeters have been successfully miniaturised to provide the detailed measurements required across the face. The headform used in this research was scanned at 709 individual locations to make a wireframe mesh consisting of 18 vertical contours and 49 horizontal contours covering half the manikin's frontal facial topography. Additionally, the back of the headform and neck have also been scanned at 576 locations. Each scanned location has been used as a viable dosimeter position on the headform and represents a grid intersection point on the developed computer wireframe. A series of exposures recorded by dosimeters have been translated into three dimensional exposure ratio maps, representing ambient solar ultraviolet exposure. High dosimeter density has allowed for the development of individual topographic contour models which take into account complex variation in the face and improve upon previously employed techniques which utilise fewer dosimeters to interpolate exposure across facial contours. Exposure ratios for solar zenith angle ranges of 0 degrees -30 degrees, 30 degrees -50 degrees, and 50 degrees -80 degrees have been developed.     

Signal transduction pathways of mantle cell lymphoma: a phosphoproteome-based study

Mantle cell lymphoma (MCL) is an incurable hematologic malignancy whose pathogenesis is only partly understood. The aim of the present study was to define a "core phosphoproteome" in MCL cell lines that is representative of primary MCL in order to improve knowledge of the signal transduction pathways involved in its tumorigenesis. We have analyzed phosphorylated proteins in several MCL cell lines by immobilized metal affinity chromatography and separation by 2-D PAGE, followed by RP-HPLC coupled with MS/MS identification. These data were correlated with information on copy number gains obtained by SNP-chip analysis. Several of the proteins identified could be linked to a specific signal transduction pathway, and have been recently recognized as important players in MCL pathogenesis, such as nuclear factor-kappaB (NF-kappaB) and phosphoinositide-3 kinase-mammalian target of rapamycin (PI3K-mTOR). However, our data also implicate a number of novel proteins and pathways in the pathobiology of MCL, one of which is mitochondrial signaling. A second-level analysis identified MAPK1, CK2, CK1, PKCzeta, and PKCepsilon as candidate upstream molecules. Our study provides new insights in MCL pathogenesis and helps to form the basis for testing new target-specific therapeutics.     

Evolutionary analysis of the transferrin gene in Antarctic Notothenioidei: A history of adaptive evolution and functional divergence

Organisms living in the Southern Ocean are exposed to strong environmental constraints, especially temperature. The Perciform suborder Notothenioidei, today largely endemic to the Antarctic, has developed numerous cold-adapted characters. The most striking peculiarity of this group of fish is the drastic reduction of hemoglobin content in their blood. This condition gives rise to a low metabolic demand of iron. Recently, we have undertaken a study to add new insights on iron metabolism in hemoglobinless fish. By taking advantage to our previous studies on transferrins from Antarctic Notothenioids, in this article we compared the evolutionary properties of these sequences to those from other fish groups and mammals. Our findings based on analysis of dN/dS ratio and on the results of the relative rate ratio test suggest that the transferrin gene has undergone positive selection in fish but not in mammals. The results of type I functional divergence provide statistical evidence for shifted evolutionary rate after speciation. Finally, when superimposed onto the three-dimensional structure of transferrin, the sites identified as responsible of the divergence in Notothenioids appear to cluster preferentially at non-iron binding locations, occupying surface locations that might affect the rate of iron binding and/or release in a cold environment.     

Differential involvement of mussel hemocyte sub-populations in the clearance of bacteria

Mussels are filter-feeders living in a bacteria-rich environment. We have previously found that numerous bacterial species are naturally present within the cell-free hemolymph, including several of the Vibrio genus, whereas the intra-cellular content of hemocytes was sterile. When bacteria were injected into the circulation of the mussel, the number of living intra-hemocyte bacteria dramatically increased in less than an hour, suggesting intense phagocytosis, then gradually decreased, with no viable bacteria remaining 12h post-injection for Micrococcus lysodeikticus, 24h for Vibrio splendidus and more than 48 h for Vibrio anguillarum. The total hemocyte count (THC) was dramatically lowered by the bacterial injections, as quantified by flow cytometry. V. splendidus induced the strongest decreases with -66% 9h post-injection of living bacteria and -56% 3h post-injection of heat-killed bacteria. Flow cytometry was used to identify three main sub-populations of hemocytes, namely hyalinocytes, small granulocytes and large granulocytes. When THC was minimal, i.e. within the first 9h post-injection, proportions of the three cell categories varied dramatically, suggesting differential involvement according to the targets, but small granulocytes remained the majority. According to a decrease in their number followed by an increase (+90% at 12h with living V. splendidus), hyalinocytes also appeared to be involved as cellular effectors of antibacterial immunity, despite possessing little capacity for phagocytosis and not containing antimicrobial peptides.     

Effect of Age-Stiffening Tissues and Intraocular Pressure on Optic Nerve Damages

Age-stiffening of ocular tissues is statistically linked to glaucoma in the elderly. In this study, the effects of age-stiffening on the lamina cribrosa, the primary site of glaucomatous nerve damages, were modeled using computational finite element analysis. We showed that glaucomatous nerve damages and peripheral vision loss behavior can be phenomenologically modeled by shear-based damage criterion. Using this damage criterion, the potential vision loss for 30 years old with mild hypertension of 25mmHg intraocular pressure (IOP) was estimated to be 4%. When the IOP was elevated to 35mmHg, the potential vision loss rose to 45%; and age-stiffening from 35 to 60 years old increased the potential vision loss to 52%. These results showed that while IOP plays a central role in glaucomatous damages, age-stiffening facilitates glaucomatous damages and may be the principal factor that resulted in a higher rate of glaucoma in the elderly than the general population.     

Autophagy induced by purple <Emphasis Type="Italic">pitanga</Emphasis> (<Emphasis Type="Italic">Eugenia uniflora</Emphasis> L.) extract triggered a cooperative effect on inducing the hepatic stellate cell death

Activated hepatic stellate cells (HSC) are the major source of collagen I in liver fibrosis. Eugenia uniflora L. is a tree species that is widely distributed in South America. E. uniflora L. fruit—popularly known as pitanga—has been shown to exert beneficial properties. Autophagy contributes to the maintenance of cellular homeostasis and survival under stress situation, but it has also been suggested to be an alternative cell death pathway. Mitochondria play a pivotal role on signaling cell death. Mitophagy of damaged mitochondria is an important cell defense mechanism against organelle-mediated cell death signaling. We previously found that purple pitanga extract induced mitochondrial dysfunction, cell cycle arrest, and death by apoptosis and necrosis in GRX cells, a well-established activated HSC line. We evaluated the effects of 72-h treatment with crescent concentrations of purple pitanga extract (5 to 100 μg/mL) on triggering autophagy in GRX cells, as this is an important mechanism to cells under cytotoxic conditions. We found that all treated cells presented an increase in the mRNA expression of autophagy-related protein 7 (ATG7). Concomitantly, flow cytometry and ultrastructural analysis of treated cells revealed an increase of autophagosomes/autolysosomes that consequentially led to an increased mitophagy. As purple pitanga extract was previously found to be broadly cytotoxic to GRX cells, we postulated that autophagy contributes to this scenario, where cell death seems to be an inevitable fate. Altogether, the effectiveness on inducing activated HSC death can make purple pitanga extract a good candidate on treating liver fibrosis.