Studies on the relationship between the pathogenicity of Paracoccidioides brasiliensis in mice and its growth rate under different oxygen atmospheres

We performed comparative studies of the pathogenicity of six strains of Paracoccidioides brasiliensis (Bt-9, Bt-4, Pb-9, Pb-18, Bt-7 and B-1183) for young adult male ddY mice and the growth rate of each strain under different oxygen atmospheres (aerobic, micro-aerobic and anaerobic atmospheres) at 37 °C. 10⁶ units of yeast cells were intravenously injected into each mouse. The pathogenicity of each isolate was determined by a scoring system based on organ culture and histopathological findings. The growth rates under different oxygen atmospheres were determined by a scoring system in which 300 fungal units per strain were counted. The strain Bt-9 showed the greatest pathogenicity, followed by Bt-4. Pb-9 and Pb-18 had on intermediate rank of pathogenicity. Bt-7 and B-1183 were the least pathogenic of the strains tested. Except for strain Bt-7 all strains showed an excellent growth under an aerobic atmosphere. Bt-4 and Bt-9 also showed excellent growth under a micro-aerobic atmosphere, followed by Pb-9, whereas the growth of Pb-18, Bt-7 and B-1183 was limited. There was a correlation between the growth rate under a micro-aerobic atmosphere and the pathogenicity of a strain. The growth rate of P. brasiliensis under a micro-aerobic atmosphere strongly correlated to its pathogenicity.     

Effect of temperature and salinity on the gastric evacuation of juvenile sole Solea solea and Solea senegalensis

The juveniles of Senegal sole, Solea senegalensis, Kaup 1858, and common sole, Solea solea (Linnaeus 1758) concentrate in estuarine and coastal nurseries of widely differing temperatures and salinities. Yet, little is known about the effect of these physiologically important variables on the gastric evacuation rates of these species. Gastric evacuation experiments were performed on juveniles of S. senegalensis and S. solea. Three temperatures were tested, 26, 20 and 14°C at a salinity of 35‰. A low salinity experiment was also carried out at 15‰, at 26°C. Experimental conditions intended to reflect conditions in estuarine and coastal nurseries where juveniles of these species spend their first years of life. The relation between stomach contents and time was best described by exponential regression models for both species. An analysis of covariance (ancova ) was performed in order to test differences in evacuation rate due to temperature and salinity (slope of evacuation time against stomach contents) for each species. While increasing temperature increased evacuation rates in both species (although not at 26°C in S. solea), the effect of low salinity differed among species, leading to a decrease in gastric evacuation rate in that of S. senegalensis and an increase in S. solea. Differences in gastric evacuation rate between species were related to its metabolic optimums and to its distribution in the nursery area where fish were captured. Implications for the habitat use of estuarine and coastal nurseries are discussed.     

Phylogeographic evidence for two species of muriqui (genus Brachyteles)

The taxonomy of muriquis, the largest extant primates in the New World, is controversial. While some specialists argue for a monotypic genus (Brachyteles arachnoides), others favor a two‐species classification, splitting northern muriquis (Brachyteles hypoxanthus) from southern muriquis (B. arachnoides). This uncertainty affects how we study the differences between these highly endangered and charismatic primates, as well as the design of more effective conservation programs. To address this issue, between 2003 and 2017 we collected over 230 muriqui fecal samples across the genus’ distribution in the Brazilian Atlantic Forest, extracted DNA from these samples, and sequenced 423 base pairs of the mitochondrial DNA (mtDNA) control region. Phylogenetic and species delimitation analyses of our sequence dataset robustly support two reciprocally monophyletic groups corresponding to northern and southern muriquis separated by an average 12.7% genetic distance. The phylogeographic break between these lineages seems to be associated with the Paraíba do Sul River and coincides with the transition between the north and south Atlantic Forest biogeographic zones. Published divergence estimates from whole mitochondrial genomes and nuclear loci date the split between northern and southern muriquis to the Early Pleistocene (ca. 2.0 mya), and our new mtDNA dataset places the coalescence time for each of these two clades near the last interglacial (ca. 120–80 kya). Our results, together with both phenotypic and ecological differences, support recognizing northern and southern muriquis as sister species that should be managed as distinct evolutionarily significant units. Given that only a few thousand muriquis remain in nature, it is imperative that conservation strategies are tailored to protect both species from extinction.     

Phylogenetic relationships,population demography,and species delimitation of the Alouatta belzebul species complex (Atelidae: Alouattinae)

Primates - Howler monkeys (genus Alouatta) exhibit the most extensive distribution among platyrrhines, comprising Mesoamerican and South American species groups, with the South American group...     

Morphological differences between an artificial lentic and adjacent lotic environments in a characid species

Dam constructions cause fundamental changes in the natural landscape, creating new ecological and evolutionary challenges for aquatic organisms. In some cases, such water impoundments have been related with morphological changes in organisms. Understanding how populations respond to rapid environmental changes imposed by dams is the first step to elucidate the consequences that disturbed habitats may have on species evolution. In this work, we analyzed shape and size variation in Bryconamericus iheringii Boulenger 1887 from the Chasqueiro stream basin, south of Brazil, which was recently dammed. We used linear measurements and geometric morphometrics to identify morphological differences among specimens from the reservoir (lentic habitat) compared to the habitat upstream and downstream of the dam (lotic habitats). We also tested for size- and shape-related sexual dimorphism to determine whether variations observed were the same for both sexes. We found that B. iheringii from the artificial reservoir were distinct in shape and size to those from their natural habitat in the stream. The size variation between environments was the same for both sexes, but the shape variation differed between males and females. Regarding the linear measurements, lotic populations were larger (greater body length, width, pectoral fin base length and caudal peduncle length), probably in response to increased swimming activity. Regarding body shape, we found that both sexes have a more fusiform body in lotic habitats than in the reservoir. In addition, females showed an altered mouth position that was distinct between these environments. This work indicates that the water reservoir seems to be an important factor influencing morphological variation in B. iheringii, a species with sexual shape dimorphism.

     

Peptaibol,Secondary‐Metabolite,and Hydrophobin Pattern of Commercial Biocontrol Agents Formulated with Species of the Trichoderma harzianum Complex

The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics in plant‐protective Trichoderma species, which are successfully used against economically relevant bacterial and fungal plant pathogens, certainly contributes to a better understanding of these complex antagonistic interactions. We analyzed five commercial biocontrol agents (BCAs), namely Canna^®, Trichosan^®, Vitalin^®, Promot^® WP, and TrichoMax^®, formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well‐established, HPLC/MS‐based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N‐terminus, the C‐terminus of which is reduced to a 1,2‐amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma‐ based BCAs, contributing 95% of the UHPLC‐UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species‐specific hydrophobins, as well as non‐peptaibiotic secondary metabolites, were detected, the latter being known for their antifungal, siderophore, or plant‐growth‐promoting activities. Notably, none of the isolates produced low‐molecular weight mycotoxins.     

α-Tocopherol regulates ectonucleotidase activities in synaptosomes from rats fed a high-fat diet

α-Tocopherol (α-Toc) is involved in various physiologic processes, which present antioxidant and neuroprotective properties. High-fat diets have an important role in neurodegenerative diseases and neurological disturbances. This study aimed to investigate the effects of treatment with α-Toc and the consumption of high-fat diets on ectonucleotidase activities in synaptosomes of cerebral cortex, hippocampus and striatum of rats. Animals were divided into four different groups, which received standard diet (control), high-fat saturated diet (HF), α-Toc and high-fat saturated diet plus α-Toc (α-Toc + HF). High-fat saturated diet was administered ad libitum and α-Toc by gavage using a dose of 50 mg·kg(-1). After 3 months of treatment, animals were submitted to euthanasia, and cerebral cortex, hippocampus and striatum were collected for biochemical assays. Results showed that adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) hydrolysis in the cerebral cortex, hippocampus and striatum were decreased in HF in comparison to the other groups (P < 0·05). When rats that received HF were treated with α-Toc, the activity of the ectonucleotidases was similar to the control. ATP, ADP and AMP hydrolysis in the cerebral cortex, hippocampus and striatum were increased in the α-Toc group when compared with the other groups (P < 0·05). These findings demonstrated that the HF alters the purinergic signaling in the nervous system and that the treatment with α-Toc was capable of modulating the adenine nucleotide hydrolysis in this experimental condition.     

Analysis of socio-demographic and systemic health factors and the normative conditions of oral health care in a population of the Brazilian elderly

doi: 10.1111/j.1741‐2358.2010.00446.x
Analysis of socio‐demographic and systemic health factors and the normative conditions of oral health care in a population of the Brazilian elderly Objective: To investigate the association of socio‐demographic and systemic health factors according to the normative conditions of oral health care (dental caries, edentulism, periodontal disease and oral mucosal lesion) in elderly individuals. Material and methods: A cross‐sectional study was carried out in a group of elderly with access to community health care (n = 200). The normative conditions of oral health were then investigated according to the WHO and the SB Brazil criteria. Bivariate analyses were evaluated by the chi‐square test and Fisher’s exact test. An estimation of prevalence for the covariates was performed using Poisson’s regression models. Results: The prevalence of edentulism and oral mucosal lesions was detected in 58% and 21.5% of elderly patients, respectively. In the dentate subjects, the prevalence of dental caries and periodontal disease was 51.2% and 20.8%, respectively. Older men and individuals from lower‐income groups exhibited a higher prevalence of dental caries. Elderly women, illiterate individuals, and individuals over the age of 65 years exhibited a higher prevalence of edentulism. Elderly 60–64 years old and those who are employed had a significant association with periodontal disease. Conclusion: Socio‐demographic factors were associated with some notable oral diseases in the elderly.     

Iron depletion affects nitrogenase activity and expression of nifH and nifA genes in Herbaspirillum seropedicae

Herbaspirillum seropedicae Z67 is a nitrogen-fixing bacterium able to colonize the rhizosphere and the interior of several plants. As iron is a key element for nitrogen fixation, we examined the response of this microorganism to iron deficiency under nitrogen fixing conditions. We identified a H. seropedicae exbD gene that was induced in response to iron limitation and is involved in iron homeostasis. We found that an exbD mutant grown in iron-chelated medium is unable to fix nitrogen. Moreover, we provide evidence that expression of the nifH and nifA genes is iron dependent in a H. seropedicae genetic background.