Effects of dietary crude protein on fertility: Meta-analysis and meta-regression

Studies used to evaluate effects of dietary intervention on fertility may be subject to confounding because modification of one nutritional input requires a change in at least one other input. Meta-analytical modeling allows examination of a main intervention for a series of studies, but also an examination of a series of related effects through use of meta-regression. Effects of dietary crude protein (CP) on fertility were examined using this approach. We obtained 21 studies containing 32 comparisons that had pregnancy or conception data and met the eligibility criteria for meta-analysis of randomized controlled experiments providing information on diets used. Publications that contained data on prospective, randomized controlled experiments examining effects of dietary CP, either concentrations or degradability, or effects of a specific feed ingredient intervention on fertility were identified. Details on dietary formulation and diet intake were extracted from the publications, as were measures of urea in blood or plasma. Estimated fixed and random effects relative risks showed that risk of conception was lower in cows fed higher CP or more degradable CP diets (fixed effect (Mantel-Haenszel Relative Risk) = 0.91 (95% CI 0.84-0.98); P=0.019). This effect was homogenous (I² = 0) and not influenced by difference in blood urea N, duration of intervention, breed, parity, milk production or type of diet delivery. Significant associations among CP components of the diet and carbohydrate fractions supported the hypothesized potential for confounding, but only the amount of soluble CP eaten was a significant meta-regression covariate that reduced risk of conception. There was no evidence that the significant reduction in fiber or non-fiber carbohydrate (NFC) fractions of the diets associated with increased concentration of CP, soluble CP or rumen degradable fractions or soyabean products content of the diet influenced conception rates. Results support findings of experiments showing that increased intake of soluble CP reduced conception rates, and provides strong evidence that increased concentrations of CP or increased degradability of CP, within the ranges evaluated in the studies contributing to this meta-analysis, reduce the risk of conception in lactating dairy cattle.     

Iron deficiency differently affects metabolic responses in soybean roots

Iron deficiency responses were investigated in roots of soybean, a Strategy I plant species. Soybean responds to iron deficiency by decreasing growth, both at the root and shoot level. Chlorotic symptoms in younger leaves were evident after a few days of iron deficiency, with chlorophyll content being dramatically decreased. Moreover, several important differences were found as compared with other species belonging to the same Strategy I. The main differences are (i) a lower capacity to acidify the hydroponic culture medium, that was also reflected by a lower H(+)-ATPase activity as determined in a plasma membrane-enriched fraction isolated from the roots; (ii) a drastically reduced activity of the phosphoenolpyruvate carboxylase enzyme; (iii) a decrease in both cytosolic and vacuolar pHs; (iv) an increase in the vacuolar phosphate concentration, and (v) an increased exudation of organic carbon, particularly citrate, phenolics, and amino acids. Apparently, in soybean roots, some of the responses to iron deficiency, such as the acidification of the rhizosphere and other related processes, do not occur or occur only at a lower degree. These results suggest that the biochemical mechanisms induced by this nutritional disorder are differently regulated in this plant. A possible role of inorganic phosphate in the balance of intracellular pHs is also discussed.     

Human estrogen receptor alpha gene is a target of Runx2 transcription factor in osteoblasts

Several studies into the mechanisms involved in control of osteoblast-specific gene expression have identified Runx2 and ERalpha (estrogen receptor alpha) as essential regulators of osteoblast differentiation. Recently, interactions between Runx2 and ERalpha have been described. Here, we investigate the role of Runx2 on the regulation of ERalpha expression by determining its interaction with the F promoter, one of the multiple promoters of the human ERalpha gene and the only one active in bone. We found that, in this promoter, three Runx2-like sites are present. By electrophoretic mobility shift assay in combination with supershift and ChIP experiments, we demonstrated that Runx2 preferentially binds one of the Runx2 motifs of the F promoter. To understand whether or not they are involved in influencing F promoter activity, different promoter-reporter deletion and mutation constructs were transiently transfected into human osteoblastic cells. Comparison of luciferase activities allowed the identification of a prevalent negative role of a sequence context, within the -117,877/-117,426 region, which may be under the control of Runx2 (a) site. Finally, silencing and overexpression of endogenous Runx2 provided evidence that Runx2 has a more complex role than initially expected. In fact, Runx2 (a) and Runx2 (b) sites carried out opposite roles which are conditioned by Runx2 levels in bone cells. Therefore, the resulting F promoter activity may be tightly regulated by a dynamic interplay between these two Runx2 sites, with a predominance of negative effect of the Runx2 (a) site.     

Obestatin conformational features: a strategy to unveil obestatin's biological role?

Obestatin and its derivative Ob(11-23) are recently discovered peptides produced in the rat stomach. They have proven to be involved in the regulation of energy balance, inhibiting feeding, causing reductions in food intake, body weight and jejunal contraction in rodents. The G-protein coupled receptor, GPR39, was originally proposed as being an obestatin target receptor, but this remains controversial. As such, the molecular mechanism for obestatin's effects in vivo is still uncertain. Here we report the CD and NMR conformational analysis of obestatin and Ob(11-23). Both peptides assume a regular secondary structure in the C-terminal region of the molecule. In this region, structural elements similar to other GPCR binding neuropeptides support the identity of obestatin as a new and functionally autonomous GPCR ligand. Conversely sequence and conformational specificity point to a new farmacoforic structure, on which innovative derivatives with a potential role in the treatment of obesity can be designed and synthetized.     

Microbial Community Structure and Dynamics of Dark Fire-Cured Tobacco Fermentation

The Italian Toscano cigar production includes a fermentation step that starts when dark fire-cured tobacco leaves are moistened and mixed with ca. 20% prefermented tobacco to form a 500-kg bulk. The dynamics of the process, lasting ca. 18 days, has never been investigated in detail, and limited information is available on microbiota involved. Here we show that Toscano fermentation is invariably associated with the following: (i) an increase in temperature, pH, and total microbial population; (ii) a decrease in reducing sugars, citric and malic acids, and nitrate content; and (iii) an increase in oxalic acid, nitrite, and tobacco-specific nitrosamine content. The microbial community structure and dynamics were investigated by culture-based and culture-independent approaches, including denaturing gradient gel electrophoresis and single-strand conformational polymorphism. Results demonstrate that fermentation is assisted by a complex microbial community, changing in structure and composition during the process. During the early phase, the moderately acidic and mesophilic environment supports the rapid growth of a yeast population predominated by Debaryomyces hansenii. At this stage, Staphylococcaceae (Jeotgalicoccus and Staphylococcus) and Lactobacillales (Aerococcus, Lactobacillus, and Weissella) are the most commonly detected bacteria. When temperature and pH increase, endospore-forming low-G+C content gram-positive bacilli (Bacillus spp.) become evident. This leads to a further pH increase and promotes growth of moderately halotolerant and alkaliphilic Actinomycetales (Corynebacterium and Yania) during the late phase. To postulate a functional role for individual microbial species assisting the fermentation process, a preliminary physiological and biochemical characterization of representative isolates was performed.     

Structure elucidation and hepatotoxicity evaluation against HepG2 human cells of neo-clerodane diterpenes from Teucrium polium L

Seven neo-clerodanes (teupolins VI–XII) and eleven known compounds were isolated and characterized from leaf extracts of Teucrium polium L., a medicinal plant used in traditional and herbal medicine for its hypolipidemic, hypoglycemic, antioxidant and antiproliferative properties. The structures of these compounds were elucidated by 1D (¹H, ¹³C and DEPT) and 2D (COSY, TOCSY, HSQC, HMBC) NMR experiments and by mass spectrometry analysis. The complete stereostructure of each compound was defined with a NOESY experiment. Because the overexploitation of herbal remedies containing T. polium extracts has resulted in several cases of hepatitis, the hepatotoxic activity of pure metabolites against the human hepatoblastoma cancer cell line HepG2 was assessed by the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) test. All of the compounds showed low toxicity values at the highest concentration tested (200 μM).     

Identification of proteins undergoing glutathionylation in oxidatively stressed hepatocytes and hepatoma cells

Protein glutathionylation is a post-translational modification consisting of the formation of a mixed disulfide between protein cysteines and glutathione (GSH). To identify proteins undergoing glutathionylation in primary rat hepatocytes and in human HepG2 hepatoma cells, we radiolabeled the intracellular GSH pool with L-[(35)S] cysteine. Cells were then exposed to oxidative stress. Proteins were separated by two-dimensional gel electrophoresis under nonreducing conditions, and glutathionylated proteins were located by autoradiography and identified by mass spectrometry after tryptic digestion. Several proteins previously not known to undergo glutathionylation were thus recognized. Among the identified proteins some are the same or belong to the same functional class as those we have already identified in a previous paper on T cell blasts (actin, nucleophosmin, phosphogluconolactonase, myosin, profilin, cyclophilin A, stress 70 protein, ubiquitin in HepG2 cells and actin, peroxiredoxin 5, cytochrome C oxidase, heat shock cognate 70 in hepatocytes) while others are newly recognized (Ran specific GTPase activating protein, histidine triad nucleotide binding protein 2 in HepG2 cells and enoyl CoA hydratase in hepatocytes). The technique described proved equally applicable to a variety of cell types.     

Mice with endogenous TDP‐43 mutations exhibit gain of splicing function and characteristics of amyotrophic lateral sclerosis

TDP‐43 (encoded by the gene TARDBP) is an RNA binding protein central to the pathogenesis of amyotrophic lateral sclerosis (ALS). However, how TARDBP mutations trigger pathogenesis remains unknown. Here, we use novel mouse mutants carrying point mutations in endogenous Tardbp to dissect TDP‐43 function at physiological levels both in vitro and in vivo. Interestingly, we find that mutations within the C‐terminal domain of TDP‐43 lead to a gain of splicing function. Using two different strains, we are able to separate TDP‐43 loss‐ and gain‐of‐function effects. TDP‐43 gain‐of‐function effects in these mice reveal a novel category of splicing events controlled by TDP‐43, referred to as “skiptic” exons, in which skipping of constitutive exons causes changes in gene expression. In vivo, this gain‐of‐function mutation in endogenous Tardbp causes an adult‐onset neuromuscular phenotype accompanied by motor neuron loss and neurodegenerative changes. Furthermore, we have validated the splicing gain‐of‐function and skiptic exons in ALS patient‐derived cells. Our findings provide a novel pathogenic mechanism and highlight how TDP‐43 gain of function and loss of function affect RNA processing differently, suggesting they may act at different disease stages.