Assessment of the total effective xenoestrogen burden in extracts of human placentas

We have standardized a method to assess the total effective xenoestrogen burden (TEXB) in human placentas by the extraction and separation by high-performance liquid chromatography of two fractions containing lipophilic xenoestrogens (alpha) and endogenous hormones (beta), followed by assessing their estrogenicity in MCF-7 breast cancer cell-based E-Screen and Yeast Estrogen Screen (YES) bioassays. The means of TEXB alpha concentrations (in estradiol equivalent (Eeq) units) were 1.32 and 0.77 Eeq pM g^?1 placenta in the E-Screen and YES, respectively; TEXB beta concentrations were 6.97 and 11.56 Eeq pM g^?1 placenta, respectively. The interclass correlation coefficient was low and a fair level of agreement was observed after kappa test correction. According to the E-Screen and YES, TEXB alpha was ≥LOD in 70.0 and 55.0% of the placentas and 92.5 and 82.5% in beta, respectively. Although both bioassays can be recommended for assessing TEXB, there is greater experience with the use of the E-Screen for estrogenic assessment after extensive extraction of complex human matrices.     

Are all Mexican odonate species documented? An assessment of species richness

With the aim of protecting Mexican diversity, one current governmental task is to complete national biological inventories. In the case of odonate insects, several researchers have hypothesized that species richness is complete (205 dragonflies and 151 damselflies), but there has not been any formal exercise to test this. Thus, we have investigated whether odonate species richness (for Mexican endemics, dragonflies (suborder Anisoptera), damselflies (suborder Zygoptera) and total species) is complete using sample-based and coverage-based rarefaction curves. Along with this, we also showed how good distribution data are in the country. The rarefaction curves have indicated 100% completeness for all groups suggesting that the inventory is complete. However, species' distribution data is highly patchy regarding areas either well (e.g. central Mexico) or badly (e.g. coast of Guerrero and Oaxaca) collected. We encourage researchers to continue odonate sampling in order to support at least three conservation actions: (i) conservation assessment of endangered species; (ii) knowledge of range shifts given rising global temperatures; and (iii) increase public interest and awareness in protected, touristic areas.     

Maternal Malnutrition and Offspring Sex Determine Juvenile Obesity and Metabolic Disorders in a Swine Model of Leptin Resistance

The present study aimed to determine, in a swine model of leptin resistance, the effects of type and timing of maternal malnutrition on growth patterns, adiposity and metabolic features of the progeny when exposed to an obesogenic diet during their juvenile development and possible concomitant effects of the offspring sex. Thus, four groups were considered. A CONTROL group involved pigs born from sows fed with a diet fulfilling their daily maintenance requirements for pregnancy. The treated groups involved the progeny of females fed with the same diet but fulfilling either 160% or 50% of pregnancy requirements during the entire gestation (OVERFED and UNDERFED, respectively) or 100% of requirements until Day 35 of pregnancy and 50% of such amount from Day 36 onwards (LATE-UNDERFED). OVERFED and UNDERFED offspring were more prone to higher corpulence and fat deposition from early postnatal stages, during breast-feeding; adiposity increased significantly when exposed to obesogenic diets, especially in females. The effects of sex were even more remarkable in LATE-UNDERFED offspring, which had similar corpulence to CONTROL piglets; however, females showed a clear predisposition to obesity. Furthermore, the three groups of pigs with maternal malnutrition showed evidences of metabolic syndrome and, in the case of individuals born from OVERFED sows, even of insulin resistance and the prodrome of type-2 diabetes. These findings support the main role of early nutritional programming in the current rise of obesity and associated diseases in ethnics with leptin resistance.     

A disappearing oasis in the semi-arid Chaco: Deficient palm regeneration and establishment

Palm forests of Copernicia alba are a rare habitat in the semi-arid Chaco of Northwestern Argentina, are centres of high species diversity, and provide key resources for many species. Our goal was to assess the conservation status of five C. alba patches in Northwestern Argentina: Reserve; Embarcación; Palma Sola; Vinalito; and, Talar. We compared patches to identify the sites with greatest conservation needs based on four criteria: population size structure; palm density (of individuals with height >1.30 m); probability of seedlings being browsed; and, presence of potential seed dispersers. We found that three (Embarcación, Reserve, and Talar) out of five sites had palm densities greater than 200 individuals/ha and only one site (Embarcación) showed a reverse J-shaped size structure for height. Reserve and Embarcación had the greatest probability of seedlings being browsed (0.99 ± 0.01 and 0.88 ± 0.12, respectively). A total of 14 potential disperser species of mammals and birds were recorded across the five sites. Only Reserve harboured all of the potential dispersers, but at least two potential disperser species were recorded at the other sites. None of the palm patches studied had an adequate conservation status. However, Embarcación met three out of four criteria, and therefore it can be considered to have the best conservation status in the semi-arid Chaco. Palma Sola and Vinalito have the greatest conservation needs. To conserve C. alba in Northwestern Argentina, strategies are needed that ensure seedling establishment for future populations to reach an adequate density and structure.     

Activity of the Arabidopsis RD29A and RD29B promoter elements in soybean under water stress

The constitutive and drought-induced activities of the Arabidopsis thaliana RD29A and RD29B promoters were monitored in soybean (Glycine max (L.) Merr.] via fusions with the visual marker gene β-glucuronidase (GUS). Physiological responses of soybean plants were monitored over 9 days of water deprivation under greenhouse conditions. Data were used to select appropriate time points to monitor the activities of the respective promoter elements. Qualitative and quantitative assays for GUS expression were conducted in root and leaf tissues, from plants under well-watered and dry-down conditions. Both RD29A and RD29B promoters were significantly activated in soybean plants subjected to dry-down conditions. However, a low level of constitutive promoter activity was also observed in both root and leaves of plants under well-watered conditions. GUS expression was notably higher in roots than in leaves. These observations suggest that the respective drought-responsive regulatory elements present in the RD29X promoters may be useful in controlling targeted transgenes to mitigate abiotic stress in soybean, provided the transgene under control of these promoters does not invoke agronomic penalties with leaky expression when no abiotic stress is imposed.     

hCOA3 Stabilizes Cytochrome c Oxidase 1 (COX1) and Promotes Cytochrome c Oxidase Assembly in Human Mitochondria

Cytochrome c oxidase (COX) or complex IV of the mitochondrial respiratory chain plays a fundamental role in energy production of aerobic cells. In humans, COX deficiency is the most frequent cause of mitochondrial encephalomyopathies. Human COX is composed of 13 subunits of dual genetic origin, whose assembly requires an increasing number of nuclear-encoded accessory proteins known as assembly factors. Here, we have identified and characterized human CCDC56, an 11.7-kDa mitochondrial transmembrane protein, as a new factor essential for COX biogenesis. CCDC56 shares sequence similarity with the yeast COX assembly factor Coa3 and was termed hCOA3. hCOA3-silenced cells display a severe COX functional alteration owing to a decreased stability of newly synthesized COX1 and an impairment in the holoenzyme assembly process. We show that hCOA3 physically interacts with both the mitochondrial translation machinery and COX structural subunits. We conclude that hCOA3 stabilizes COX1 co-translationally and promotes its assembly with COX partner subunits. Finally, our results identify hCOA3 as a new candidate when screening for genes responsible for mitochondrial diseases associated with COX deficiency.     

Kinetic and anion inhibition studies of a β-carbonic anhydrase (FbiCA 1) from the C4 plant Flaveria bidentis

Several β-carbonic anhydrases (CAs, EC 4.2.1.1) are present in all land plants examined thus far. Here we report the first detailed biochemical characterization of one such isoform, FbiCA 1, from the C₄ plant Flaveria bidentis, which was cloned, purified and characterized as recombinant protein. FbiCA 1 has an interesting CO₂ hydrase catalytic activity (k_cat of 1.2 × 10⁵ and k_cat/K_m of 7.5 × 10⁶ M^?1 × s^?1) and was moderately inhibited by most simple/complex inorganic anions. Potent FbiCA 1 inhibitors were also detected, such as trithiocarbonate, diethyldithiocarbamate, sulfamide, sulfamic acid, phenylboronic acid and phenylarsonic acid (K_Is in the range of 4–60 μM). Such inhibitors may be used as tools to better understand the role of various β-CA isoforms in photosynthesis.