Genetic and symbiotic diversity of nitrogen-fixing bacteria isolated from agricultural soils in the Western Amazon by using cowpea as the trap plant

Cowpea is a legume of great agronomic importance that establishes symbiotic relationships with nitrogen-fixing bacteria. However, little is known about the genetic and symbiotic diversity of these bacteria in distinct ecosystems. Our study evaluated the genetic diversity and symbiotic efficiencies of 119 bacterial strains isolated from agriculture soils in the western Amazon using cowpea as a trap plant. These strains were clustered into 11 cultural groups according to growth rate and pH. The 57 nonnodulating strains were predominantly fast growing and acidifying, indicating a high incidence of endophytic strains in the nodules. The other 62 strains, authenticated as nodulating bacteria, exhibited various symbiotic efficiencies, with 68% of strains promoting a significant increase in shoot dry matter of cowpea compared with the control with no inoculation and low levels of mineral nitrogen. Fifty genotypes with 70% similarity and 21 genotypes with 30% similarity were obtained through repetitive DNA sequence (BOX element)-based PCR (BOX-PCR) clustering. The 16S rRNA gene sequencing of strains representative of BOX-PCR clusters showed a predominance of bacteria from the genus Bradyrhizobium but with high species diversity. Rhizobium, Burkholderia, and Achromobacter species were also identified. These results support observations of cowpea promiscuity and demonstrate the high symbiotic and genetic diversity of rhizobia species in areas under cultivation in the western Amazon.     

Changes in blood metabolic parameters during the development of Walker-256 tumour-induced cachexia in rats are not caused by decreased food intake

Blood metabolic parameters of Walker-256 tumour-bearing rats, on days 5, 8, 11 and 14 after implantation of tumour, were compared with those of rats without tumour fed ad libitum (free-fed control) or with reduced feeding (pair-fed control), similar to the anorexic tumour-bearing rats. Cachexia parameters and tumour mass also were investigated. In general, especially on day 14 after implantation of tumour, there was reduction of body mass, gastrocnemius muscle mass, food intake and glycemia and increase of blood triacylglycerol, free fatty acids, lactate and urea, compared with free-fed controls rats. These changes did not occur in pair-fed control, except a slight reduction of glycemia. Pair-fed control showed no significant changes in blood cholesterol and glycerol in comparison with free-fed control, although there was reduction of cholesterol and increase of blood glycerol on day 14 after tumour implantation compared with pair-fed control. The results demonstrate that, besides the characteristic signs of the cachexia syndrome such as anorexia, weight loss and muscle catabolism, Walker-256 tumour-bearing rats show several blood metabolic alterations, some of which begin as early as day 5 after implantation of tumour, and are accentuated during the development of cachexia. Evidence that the alterations of blood metabolic parameters of tumour-bearing rats were not found in pair-fed control indicate that they were not caused by decreased food intake. These changes were probably mediated by factors produced by tumour or host tissue in response to the presence of tumour.     

Decreased response to cAMP in the glucose and glycogen catabolism in perfused livers of Walker-256 tumor-bearing rats

The hepatic response to cyclic adenosine monophosphate (cAMP) and N6-monobutyryl-cAMP (N6-MB-cAMP) in the glucose and glycogen catabolism and hepatic glycogen levels were evaluated in Walker-256 tumor-bearing rats, on days 5 (WK5), 8 (WK8), and 11 (WK11) after the implantation of tumor. Rats without tumor fed ad libitum (fed control rats) or that received the same daily amount of food ingested by anorexics tumor-bearing rats (pair-fed control rats) or 24 h fasted (fasted control rats) were used as controls. Glucose and glycogen catabolism were measured in perfused liver. Hepatic glycogen levels were lower (p < 0.05) in WK5, WK8, and WK11 rats in comparison with fed control rats, but not in relation to the pair-fed control rats. However, the stimulatory effect of cAMP (3 and 9 μM) in the glycogen catabolism was lower (p < 0.05), respectively, in WK5 and WK8 rats compared to the pair-fed and fed control rats. Accordingly, the suppressive effect of cAMP (6 μM) in the glucose catabolism, under condition of depletion of hepatic glycogen (24 h fast), was lower (p < 0.05) in WK5 and WK11 rats than in fasted control rats. Similarly, the suppressive effect of N6-MB-cAMP (1 μM), a synthetic analogue of cAMP that it is not degraded by phosphodiesterase 3B (PDE3B), in the glucose catabolism was lower (p < 0.05) in WK5 rats compared to fasted control rats. In conclusion, livers of Walker-256 tumor-bearing rats showed lower response to cAMP in the glucose and glycogen catabolism in various stages of tumor development (days 5, 8 and 11), which was probably not due to the lower hepatic glycogen levels nor due to the increased activity of PDE3B.     

Ill nature: Disease hotspots as threats to biodiversity

Diseases are part of the natural world, but human activities may affect and disrupt the natural dynamics of diseases, threatening wildlife species and human welfare. We listed the number of species threatened by diseases and compiled their distributional ranges. Based on such data we identify global disease hotspots, regions where disrupted disease dynamics threaten to decimate several species into extinction. The number of species threatened by disease may increase, and climate change may act synergistically increasing the severity of disease incidence in the hotspots, and drive the emergence of new disease hotspots. Until now diseases were thought to play a secondary role in the biodiversity extinction crisis, but the global threat scenario is so dynamic that if we do not bring diseases to the forefront of conservation actions and policies, they may not only bring species into extinction but they may also affect human populations as well.     

Impact of continuous axenic cultivation in Leishmania infantum virulence

Experimental infections with visceral Leishmania spp. are frequently performed referring to stationary parasite cultures that are comprised of a mixture of metacyclic and non-metacyclic parasites often with little regard to time of culture and metacyclic purification. This may lead to misleading or irreproducible experimental data. It is known that the maintenance of Leishmania spp. in vitro results in a progressive loss of virulence that can be reverted by passage in a mammalian host. In the present study, we aimed to characterize the loss of virulence in culture comparing the in vitro and in vivo infection and immunological profile of L. infantum stationary promastigotes submitted to successive periods of in vitro cultivation. To evaluate the effect of axenic in vitro culture in parasite virulence, we submitted L. infantum promastigotes to 4, 21 or 31 successive in vitro passages. Our results demonstrated a rapid and significant loss of parasite virulence when parasites are sustained in axenic culture. Strikingly, the parasite capacity to modulate macrophage activation decreased significantly with the augmentation of the number of in vitro passages. We validated these in vitro observations using an experimental murine model of infection. A significant correlation was found between higher parasite burdens and lower number of in vitro passages in infected Balb/c mice. Furthermore, we have demonstrated that the virulence deficit caused by successive in vitro passages results from an inadequate capacity to differentiate into amastigote forms. In conclusion, our data demonstrated that the use of parasites with distinct periods of axenic in vitro culture induce distinct infection rates and immunological responses and correlated this phenotype with a rapid loss of promastigote differentiation capacity. These results highlight the need for a standard operating protocol (SOP) when studying Leishmania species.     

Biomass-Derived Inhibitors of Holocellulases

Enzymes constitute a major monetary cost in the bioconversion of holocellulose to ethanol. Identifying enzyme inhibitors and moderating their effects is one approach that may help to overcome this issue. Most inhibitors that reduce the hydrolysis activity of holocellulases are released as the holocellulosic biomass is broken down in the pretreatment and hydrolysis steps. Recent reports in the literature have shown that the major inhibitors or deactivators of cellulases are phenols and xylooligosaccharides. The bioconversion of hemicelluloses by hemicellulases also has important practical applications in various agro-industrial processes in addition to the conversion of hemicellulosic biomass to fuels and chemicals. Hemicellulases, such as β-xylosidases, may also help alleviate the inhibitory effect of xylooligosaccharides to cellulases. However, compared to cellulases, less is known about the inhibition or deactivation of hemicellulases and pectinases, especially for inhibitors that are generated during pre-treatment and the hydrolysis of lignocellulosic substrates. Considering the importance of such enzymes for the complete degradation of lignocellulosic substrates, this review provides a broad view of the effect of inhibitors of holocellulases (cellulases, hemicellulases, and pectinases).     

Bacterial cellulose modified using recombinant proteins to improve neuronal and mesenchymal cell adhesion

A wide variety of biomaterials and bioactive molecules have been applied as scaffolds in neuronal tissue engineering. However, creating devices that enhance the regeneration of nervous system injuries is still a challenge, due the difficulty in providing an appropriate environment for cell growth and differentiation and active stimulation of nerve regeneration. In recent years, bacterial cellulose (BC) has emerged as a promising biomaterial for biomedical applications because of its properties such as high crystallinity, an ultrafine fiber network, high tensile strength, and biocompatibility. The small signaling peptides found in the proteins of extracellular matrix are described in the literature as promoters of adhesion and proliferation for several cell lineages on different surfaces. In this work, the peptide IKVAV was fused to a carbohydrate-binding module (CBM3) and used to modify BC surfaces, with the goal of promoting neuronal and mesenchymal stem cell (MSC) adhesion. The recombinant proteins IKVAV-CBM3 and (19)IKVAV-CBM3 were successfully expressed in E. coli, purified through affinity chromatography, and stably adsorbed to the BC membranes. The effect of these recombinant proteins, as well as RGD-CBM3, on cell adhesion was evaluated by MTS colorimetric assay. The results showed that the (19)IKVAV-CBM3 was able to significantly improve the adhesion of both neuronal and mesenchymal cells and had no effect on the other cell lineages tested. The MSC neurotrophin expression in cells grown on BC membranes modified with the recombinant proteins was also analyzed.     

MIF induces osteoclast differentiation and contributes to progression of periodontal disease in mice

Periodontal disease (PD) is a chronic inflammatory and alveolar bone destructive disease triggered by microorganisms from the oral biofilm. Oral inoculation of mice with the periodontopathogen Aggregatibacter actinomycetemcomitans (Aa) induces marked alveolar bone loss and local production of inflammatory mediators, including Macrophage Migration Inhibitory Factor (MIF). The role of MIF for alveolar bone resorption during PD is not known. In the present study, experimental PD was induced in BALB/c wild-type mice (WT) and MIF knockout mice (MIF^?/?) through oral inoculation of Aa. Despite enhanced number of bacteria, MIF^?/? mice had reduced infiltration of TRAP-positive cells and reduced alveolar bone loss. This was associated with decreased neutrophil accumulation and increased levels of IL-10 in periodontal tissues. TNF-α production was similar in both groups. In vitro, LPS from Aa enhanced osteoclastic activity in a MIF-dependent manner. In conclusion, MIF has role in controlling bacterial growth in the context of PD but contributes more significantly to the progression of bone loss during PD by directly affecting differentiation and activity of osteoclasts.     

Asymbiotic seed germination and in vitro seedling development of the threatened orchid Hoffmannseggella cinnabarina

Hoffmannseggella cinnabarina has not been found in the wild for the last 70?yr in the State of S?o Paulo and, therefore, wild populations of this native orchid are thought to be extinct. This investigation studied seed storage at a low temperature, in vitro germination, and seedling development of H. cinnabarina in order to establish an optimized protocol for propagation, and thus assure species conservation. Seeds of different ages were incubated on Knudson C (KC), Murashige and Skoog, and Vacin and Went media with or without 1???M of N⁶-benzyladenine (BA) and exposed to either 12 or 16?h of light (30???mol?m^?2?s^?1 at 26?±?2°C). Seed surface sterilization was deleterious to 3-mo-old seeds and severely reduced the viability of the 4-mo-old seeds. More mature seeds were not affected by the sterilization procedure. In general, the germination of 4-, 5-, 6-, and 7-mo-old seeds increased when BA was added to the culture medium especially under 16?h of light. Germination rates were highest with 8- and 9-mo-old seeds, and application of BA failed to enhance germination rates further. Developmental studies revealed that this cytokinin reduced seed and protocorm mortality rates; however, protocorm development was negatively affected in its presence. Seedling development was more pronounced when KC medium with 16?h of light was used. Long-term seed storage at 4°C did not provide promising results. The protocol described in this study proved to be efficient and relevant to in vitro seed germination and initial development of H. cinnabarina, and thus will contribute to conservation of this orchid species.     

Blood glucose control for individuals with type-2 diabetes: acute effects of resistance exercise of lower cardiovascular-metabolic stress

ABSTRACT: Moreira, SR, Sim?es, GC, Moraes, JFVN, Motta, DF, Campbell, CSG, and Sim?es, HG. Blood glucose control for individuals with type-2 diabetes: Acute effects of resistance exercise of lower cardiovascular-metabolic stress. J Strength Cond Res 26(10): 2806-2811, 2012-This study compared the effects of resistance exercise (RE) intensities on blood glucose (GLUC) of individuals without (ND) and with type-2 diabetes (T2D). Nine individuals with T2D and 10 ND performed: (a) RE circuit at 23% of 1 maximal repetition (1RM) (RE_L); (b) RE circuit at 43% 1RM (RE_M); and (c) control (CON) session. Blood lactate (LAC) and GLUC were measured before, during, and postinterventions. Double product (DP) and rate of perceived exertion (RPE) were recorded. The area under the curve (AUC) revealed the effects of RE circuits in reducing GLUC in individuals with T2D (RE_L: 12,556 ± 3,269 vs. RE_M: 13,433 ± 3,054 vs. CON: 14,576 ± 3,922 mg.dl.145 minutes; p < 0.05) with a lower AUC of GLUC in RE_L in comparison to RE_M. Similarly, for ND the RE_L reduced the AUC of GLUC when compared with RE_M and CON (RE_L: 10,943 ± 956 vs. RE_M: 12,156 ± 1,062 vs. CON: 11,498 ± 882 mg.dl.145 minutes; p < 0.05). The AUC of GLUC was higher for T2D compared with ND on CON condition (p = 0.02). However, after RE circuits the difference between groups for AUC of GLUC was abolished. The RE_M for T2D was more stressful when compared with RE_L for LAC (CON: 1.3 ± 0.5 vs. RE_L: 5.5 ± 1.5 vs. RE_M: 6.8 ± 1.3 mmol·L; p < 0.05), DP (CON: 8,415 ± 1,223 vs. RE_L: 15,980 ± 2,007 vs. RE_M: 18,047 ± 3,693 mmHg.bpm; p < 0.05), and RPE (RE_L: 11 ± 2 vs. RE_M: 13 ± 2 Borg Scale; p < 0.05). We concluded that RE_L and RE_M were effective in reducing GLUC for individuals with T2D, with lower cardiovascular-metabolic and perceptual stress being observed for RE_L. These data suggest that acute RE sessions at light or moderate intensities are effective for controlling GLUC in individuals with T2D.