Phylogeography of the cactophilic species Drosophila gouveai: demographic events and divergence timing in dry vegetation enclaves in eastern Brazil

Aim  The aim of this study was to assess the causal mechanisms underlying populational subdivision in Drosophila gouveai , a cactophilic species associated with xeric vegetation enclaves in eastern Brazil. A secondary aim was to investigate the genetic effects of Pleistocene climatic fluctuations on these environments.
Location  Dry vegetation enclaves within the limits of the Cerrado domain in eastern Brazil.
Methods  We determined the mitochondrial DNA haplotypes of 55 individuals (representing 12 populations) based on sequence data of a 483-bp fragment from the cytochrome c oxidase subunit II (COII) gene. Phylogenetic and coalescent analyses were used to test for the occurrence of demographic events and to infer the time of divergence amongst genetically independent groups.
Results  Our analyses revealed the existence of two divergent subclades (G1 and G2) plus an introgressed clade restricted to the southernmost range of D. gouveai . Subclades G1 and G2 displayed genetic footprints of range expansion and segregated geographical distributions in south-eastern and some central highland regions, east and west of the Paraná River valley. Molecular dating indicated that the main demographic and diversification events occurred in the late to middle Pleistocene.
Main conclusions  The phylogeographical and genetic patterns observed for D. gouveai in this study are consistent with changes in the distribution of dry vegetation in eastern Brazil. All of the estimates obtained by molecular dating indicate that range expansion and isolation pre-dated the Last Glacial Maximum, occurring during the late to middle Pleistocene, and were probably triggered by climatic changes during the Pleistocene. The current patchy geographical distribution and population subdivision in D. gouveai is apparently closely linked to these past events.     

Paracoccidioides brasiliensis Interferes on Dendritic Cells Maturation by Inhibiting PGE2 Production

Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil, whose etiologic agent is the thermodimorphic fungus of the genus Paracoccidioides, comprising cryptic species of Paracoccidioides brasiliensis, S1, PS2, PS3 and Paracoccidioides lutzii. The mechanisms involved in the initial interaction of the fungus with cells of the innate immune response, as dendritic cells (DCs), deserve to be studied. Prostaglandins (PGs) are eicosanoids that play an important role in modulating functions of immune cells including DCs. Here we found that human immature DCs derived from the differentiation of monocytes cultured with GM-CSF and IL-4 release substantial concentrations of PGE₂, which, however, were significantly inhibited after challenge with P. brasiliensis. In vitro blocking of pattern recognition receptors (PRRs) by monoclonal antibodies showed the involvement of mannose receptor (MR) in PGE₂ inhibition by the fungus. In addition, phenotyping assays showed that after challenge with the fungus, DCs do not change their phenotype of immature cells to mature ones, as well as do not produce IL-12 p70 or adequate concentrations of TNF-α. Assays using exogenous PGE₂ confirmed an association between PGE₂ inhibition and failure of cells to phenotypically mature in response to P. brasiliensis. We conclude that a P. brasiliensis evasion mechanism exists associated to a dysregulation on DC maturation. These findings may provide novel information for the understanding of the complex interplay between the host and this fungus.     

Culture of chondrocytes in medium supplemented with fetal calf serum or a serum substitute: Ultroser G

Fetal calf serum and a serum substitute, Ultroser G, were compared for their effects on the growth curves, clonal growth and cell cycle progression of rabbit chondrocytes in primary culture and during at least three cell passages and included a screen for the maintenance of cartilage-like differentiation i.e. the presence of type II collagen. Proliferation was also compared with another serum substitute, Nu-Serum. Ultroser G is shown to be equivalent to fetal calf serum as far as chondrocyte proliferation is concerned, clonal growth is improved and biosynthesis of type II collagen is maintained in primary culture.     

Liposome-mediated DNA transfer in eukaryotic cells: Dependence of the transfer efficiency upon the type of liposomes used and the host cell cycle stage

The pBR322 plasmid containing the sequence encoding β-lactamase, the enzyme conferring resistance to ampicillin, was encapsulated in liposomes of different phospholipid composition and incubated with synchronized cells. In mitotic cells as compared to cells synchronized in G₁, twice as many exogeneous DNA molecules were found associated with the cell nuclear DNA, when fluid, neutral liposomes were used. These liposomes are taken up by the cells mainly via endocytosis. When fluid, negatively charged liposomes were used as carriers about the same number of exogeneous DNA molecules were found associated with the nuclear DNA both in mitotic and in G₁-synchronized cells. The efficiency for gene transfer of liposomes entering the cells by different mechanisms was further studied and expressed both by the fraction of the radioactive plasmid associated with the nuclear DNA and by the level of the β-lactamase activity detected in the transfected cells. It appears that liposomes entering the cells mainly via an energy-dependent mechanism are more efficient for this type of DNA transfer.     

Properties of succinylated wheat-germ agglutinin.

The physicochemical and binding properties of succinylated wheat germ agglutinin are described in comparison with these of unmodified wheat germ agglutinin. Succinylated wheat germ agglutinin is an acidic protein with a pI of 4.0 +/- 0.2 while the native lectin is basic, pI of 8.5. The solubility of succinylated wheat germ agglutinin is about 100 times higher than that of the unmodified lectin at neutral pH. Both lectins are dimeric at pH down to 5, and the dissociation occurs at pH lower than 4.5. The binding of oligosaccharides of N-acetylglucosamine to both lectins is very similar on the basis of fluorescence and phosphorescence studies. The minimal concentration required to agglutinate rabbit red blood cells is about 2 microgram/ml with both lectins and the concentrations of N-acetylglucosamine and di-N-acetylchitobiose which inhibit agglutination are similar with both lectins. The number of succinylated wheat germ agglutinin molecules bound to the surface of mouse thymocytes was ten times lower than that of the unmodified lectin although the apparent binding constant was only slightly different between the two lectins. The dramatic decrease of the apparent number of cell surface receptors upon succinylation of the lectin is discussed on the basis of the decrease of the isoelectric point and of the acidic properties of the cell surface.     

Non-native prey species supporting fish assemblage biomass in a Neotropical reservoir

The present study aimed to investigate the role of four non-native invertebrates in supporting fish biomass as well as their influence on the carbon flow into the Volta Grande reservoir food web. The fish samples were carried out quarterly between October 2015 and July 2016 using gillnets. At the sampled sites, four non-native invertebrates (golden mussel, Asian clam, trumpet snail and Amazonian prawn), which are potential prey for fish in the Volta Grande reservoir, were collected by targeted sampling using a Petersen-type bottom dredger and semi-circular sieves. The gut contents of the fish were collected and analyzed under stereoscope, and samples of muscle tissue of these fish, as well as the four non-native invertebrate species sampled, were submitted for isotopic analysis. Results obtained by the present study, by both gut content and stable isotopic analyses, pointed to a trophic structure where non-native species represent not only a strong component of the fish community, but also their main carbon source. Based on gut contents and isotopic mixing models, we found that together, non-native prey are essential carbon sources for the fish fauna, fuelling more than 40.0% of the biomass in four dominant fish species. The consumption rate of non-native bivalves by the native omnivorous fish Leporinus friderici suggested these filter-feeding organisms potentially constitute an important trophic connection between littoral consumers and pelagic energy sources. In addition, non-native prey were also prominent carbon sources for non-native fish, fuelling more than half of the biomass in peacock bass and silver croaker, suggesting these prey have a fundamental role in maintaining non-native fish populations in this system. Our results may help to understand fundamental ecological issues bringing to light the extent to which these new combinations of species influence the energy flow and ecosystem properties of the Volta Grande reservoir.

     

Sitting movement in elderly subjects with and without Parkinson’s disease: A biomechanical study

The aim of the present study was to compare kinetic, kinematic, and electromyographic variables during the sitting movement between healthy elderly and in those with Parkinson’s disease (PD) with moderate involvement. We hypothesized that subjects with PD would show difficulty in selecting the muscles for the task and that this could be related to the co-activation pattern and would be reflected in the behavior of some biomechanical variables. Fifteen subjects participated in this study, seven healthy subjects (NN group) and eight with Parkinson’s disease. Electromyography (EMG) activity of the tibialis anterior (TA), soleus (SO), vastus medialis oblique (VMO), biceps femoris (BF), and erector spinae (ES) were recorded, and biomechanical variables were calculated, during four phases of the sitting movement. Compared to healthy subjects, the subjects with PD showed more flexion at the ankle, knee, and hip joints in the initial position and lower joint velocity. However, the EMG activity and hip, knee, and ankle joint torques were not different during all phases of movement. The sitting movement in PD subjects with moderate involvement generates EMG activity and joint torques similar to healthy elderly subjects. Only a reduced movement velocity was found in PD patients during the sitting task.     

Changing Mortality Profile among HIV-Infected Patients in Rio de Janeiro,Brazil: Shifting from AIDS to Non-AIDS Related Conditions in the HAART Era

Introduction

We describe temporal trends in the mortality rates and factors associated with AIDS and non-AIDS related mortality at the Evandro Chagas Clinical Research Institute (IPEC), Oswaldo Cruz Foundation (FIOCRUZ).

Methods

Adult patients enrolling from 1986 through 2009 with a minimum follow up of 60 days were included. Vital status was exhaustively checked using patients’ medical charts, through active contact with individuals and family members and by linkage with the Rio de Janeiro Mortality database using a previously validated algorithm. The CoDe protocol was used to establish the cause of death. Extended Cox proportional hazards models were used for multivariate modeling.

Results

A total of 3530 individuals met the inclusion criteria, out of which 868 (24.6%) deceased; median follow up per patient was 3.9 years (interquartile range 1.7–9.2 years). The dramatic decrease in the overall mortality rates was driven by AIDS-related causes that decreased from 9.19 deaths/100PYs n 1986–1991 to 1.35/100PYs in 2007–2009. Non-AIDS related mortality rates remained stable overtime, at around 1 death/100PYs. Immunodeficiency significantly increased the hazard of both AIDS-related and non-AIDS-related causes of death, while HAART use was strongly associated with a lower hazard of death from either cause.

Conclusions

Our results confirm the remarkable decrease in AIDS-related mortality as the HIV epidemic evolved and alerts to the conditions not traditionally related to HIV/AIDS which are now becoming more frequent, needing careful monitoring.     

1914G variant of BCHE gene associated with enzyme activity,obesity and triglyceride levels

Polymorphisms of butyrylcholinesterase (BChE) have been reported to be associated to weight, BMI variance and hypertriglyceridemia in adults and adolescents. The aim of the present study was to investigate the association of −116A (SNP: G/A; rs1126680) and 1914G (SNP: A/G; rs3495) variants of BCHE gene with anthropometric and biochemical variables associated with obesity in population sample of 115 individuals, from Southern Brazil. Participants were grouped in two categories: obese (BMI ≥ 30) and non-obese (BMI < 30). The 1914G allele showed significantly higher frequency in the obese group, and carriers of 1914G allele showed lower mean BChE activity when compared to 1914A carriers (p = 0.006). Higher means of BMI (p = 0.02) and triglyceride (TG; p = 0.01) were found in 1914G carriers (BMI = 27.57kg/m²; TG = 150.8 mg/dL) when compared to 1914A homozygotes (BMI = 25.55 kg/m²; TG = 107.9 mg/dL). Carriers of the −116A allele showed lower mean BChE activity than usual homozygotes, and the −116A variant was found in cis with 1914G (p < 0.0001; D′ = 1). The region of BCHE gene that contains the 1914G mutation site is target of microRNAs (miRs) and the response of BChE to glucocorticoids is especially influenced by these miRs. Therefore, it is possible that the 1914G allele can be interfering in gluconeogenesis, hyperglycemia, lipolysis and body fat distribution. This lower activity may cause an imbalance in lipid metabolism, which may lead to an increased predisposition to obesity and to a lower ability to maintain metabolic homeostasis.