Role of Zinc in Zinc-α2-Glycoprotein Metabolism in Obesity: a Review of Literature

Biological Trace Element Research - Excessive adipose tissue promotes the manifestation of endocrine disorders such as reduction of the secretion of zinc-α2-glycoprotein (ZAG), an adipokine...     

Resistance of Aedes aegypti (L.) (Diptera: Culicidae) populations to organophosphates temephos in the Paraíba State, Brazil

Rumors of Aedes aegypti (L.) resistance to temephos in diferent Brazilian states justified this research, whose objective was to verify and characterize the resistance to temephos in A. aegypti populations from Paraíba State. The temephos resistance was evaluated and characterized through a diagnostic dose of 0.012 mg/l and concentration-mortality curves. The mortality data of multiple concentrations were submitted to Probit analysis, and the resistance ratios (RR) were figured out from the CL50s of the survived population and CL50 a laboratory susceptible population. All the A. aegypti populations showed resistance to temephos. The Sítio Piabas population with RR = 4.0, showed lower resistance, the Campina Grande with RR = 6.0, Lagoa do Mato with RR = 9.3 and Capim de Cheiro with RR = 9.0, showed a moderate resistance, and Boqueir?o with RR = 11.0, Brejo dos Santos with RR = 16.6 and Itaporanga with RR= 15.6, showed intermediate levels of resistance to temephos. These results confirm the need of a continuous monitoring and managing program of A. aegypti resistance in Paraíba State.     

A novel aminophospholipid transporter exclusively expressed in spermatozoa is required for membrane lipid asymmetry and normal fertilization

Through the use of a functionally unbiased signal peptide trap screen, we have discovered an ATP-dependent aminophospholipid transporter that is exclusively expressed in the acrosomal region of spermatozoa; it is about 62% similar to the flippase, FIC1. We disrupted the transporter gene and found that the size of litters from male null mice was slightly smaller than found with wild-type males. Sperm morphology and motility were the same between null and wild-type littermates, but agents (merocyanine and annexin) that measure phospholipid packing or phosphatidylserine (PS) in the outer membrane leaflet showed that PS already existed in the outer leaflet of null spermatozoa before sperm capacitation. Fertilization rates were normal when null spermatozoa were added to zona pellucida-free eggs, but in the presence of the extracellular matrix, fewer transporter(-/-) spermatozoa bound tightly or penetrated the zona pellucida (ZP), and fewer underwent acrosome reactions. In vitro fertilization was compromised, especially at early time points or at low sperm concentrations after mixing null spermatozoa and eggs. Thus, a new aminophospholipid transporter expressed exclusively in spermatozoa is critical for normal phospholipid distribution in the bilayer, and for normal binding, penetration, and signaling by the zona pellucida.     

2D-DIGE analysis of mango (Mangifera indica L.) fruit reveals major proteomic changes associated with ripening

A comparative proteomic investigation between the pre-climacteric and climacteric mango fruits (cv. Keitt) was performed to identify protein species with variable abundance during ripening. Proteins were phenol-extracted from fruits, cyanine-dye-labeled, and separated on 2D gels at pH 4-7. Total spot count of about 373 proteins spots was detected in each gel and forty-seven were consistently different between pre-climacteric and climacteric fruits and were subjected to LC-MS/MS analysis. Functional classification revealed that protein species involved in carbon fixation and hormone biosynthesis decreased during ripening, whereas those related to catabolism and the stress-response, including oxidative stress and abiotic and pathogen defense factors, accumulated. In relation to fruit quality, protein species putatively involved in color development and pulp softening were also identified. This study on mango proteomics provides an overview of the biological processes that occur during ripening.     

Effects of temperature on the life cycle,expansion, and dispersion of Aedes aegypti (Diptera: Culicidae) in three cities in Paraiba,Brazil

The mosquito Aedes aegypti is the primary vector of dengue and is common throughout tropical and subtropical regions. Its distribution is modulated by environmental factors, such as temperature. This study aimed to evaluate the influence of temperature on the life cycle and expansion of Ae. aegypti populations in the cities of Campina Grande, João Pessoa, and Patos. Samples of Ae. aegypti were collected in the three cities and raised in the laboratory. We assessed the life cycles of the three Ae. aegypti populations under six constant temperatures (16, 22, 28, 33, 36, and 39°C), selected on the basis of historical temperature tendencies of each city. We also used existing climate data to calculate projected temperature increases for all three areas. Our results suggest that Campina Grande, João Pessoa, and Patos will experience, respectively, maximum temperature increases of 0.030°C/year, 0.069°C/year, and 0.061°C/year, and minimum temperature increases of 0.019°C/year, ?0.047°C/year, and ?0.086°C/year. These projected increases will result in temperatures favorable to the Ae. aegypti life cycle, causing rapid population growth. Therefore, Ae. aegypti populations are likely to expand in the mesoregions represented by these cities.     

Biology and thermal exigency of Aedes aegypti (L.) (Diptera: Culicidae) from four bioclimatic localities of Paraíba

The present work aimed at estimating the thermal requirements for the development and the number of generations per year of Aedes aegypti (L.) under natural conditions. The life cycle of A. aegypti populations was studied at constant temperatures of 18, 22, 26, 30 and 34 degrees C, and 12 h photophase. The development period, egg viability and larval and pupal survival were evaluated daily as well as adult longevity and fecundity. The low threshold temperature of development (Tb) and the thermal constant (K) were determined. The number of generations per year in laboratory and field were also estimated. The favorable temperature to A. aegypti development is between 21 degrees C and 29 degrees C, and to longevity and fecundity is between 22 degrees C and 30 degrees C. The egg to adult basal temperature, thermal constant and the number of generations in field were, in order, 9.5, 8.5, 3.4, 7.1, 13.5 degrees C; 244.5, 273.9, 298.5, 280.9 and 161.8 degree-days; and 21.9, 23.8, 24.2, 21.1 and 22.1 generations in populations from Boqueir?o, Brejo dos Santos, Campina Grande, Itaporanga and Remígio.     

Prion Protein Promotes Kidney Iron Uptake via Its Ferrireductase Activity

Brain iron-dyshomeostasis is an important cause of neurotoxicity in prion disorders, a group of neurodegenerative conditions associated with the conversion of prion protein (PrP^C) from its normal conformation to an aggregated, PrP-scrapie (PrP^Sc) isoform. Alteration of iron homeostasis is believed to result from impaired function of PrP^C in neuronal iron uptake via its ferrireductase activity. However, unequivocal evidence supporting the ferrireductase activity of PrP^C is lacking. Kidney provides a relevant model for this evaluation because PrP^C is expressed in the kidney, and ∼370 μg of iron are reabsorbed daily from the glomerular filtrate by kidney proximal tubule cells (PT), requiring ferrireductase activity. Here, we report that PrP^C promotes the uptake of transferrin (Tf) and non-Tf-bound iron (NTBI) by the kidney in vivo and mainly NTBI by PT cells in vitro. Thus, uptake of ⁵⁹Fe administered by gastric gavage, intravenously, or intraperitoneally was significantly lower in PrP-knock-out (PrP^−/−) mouse kidney relative to PrP^+/+ controls. Selective in vivo radiolabeling of plasma NTBI with ⁵⁹Fe revealed similar results. Expression of exogenous PrP^C in immortalized PT cells showed localization on the plasma membrane and intracellular vesicles and increased transepithelial transport of ⁵⁹Fe-NTBI and to a smaller extent ⁵⁹Fe-Tf from the apical to the basolateral domain. Notably, the ferrireductase-deficient mutant of PrP (PrP^Δ51–89) lacked this activity. Furthermore, excess NTBI and hemin caused aggregation of PrP^C to a detergent-insoluble form, limiting iron uptake. Together, these observations suggest that PrP^C promotes retrieval of iron from the glomerular filtrate via its ferrireductase activity and modulates kidney iron metabolism.     

Insulin resistance in adolescents with Down syndrome: a cross-sectional study

Background

The prevalence of diabetes mellitus is higher in individuals with Down syndrome (DS) than in the general population; it may be due to the high prevalence of obesity presented by many of them. The aim of this study was to evaluate the insulin resistance (IR) using the HOMA (Homeostasis Model Assessment) method, in DS adolescents, describing it according to the sex, body mass index (BMI) and pubertal development.

Methods

15 adolescents with DS (8 males and 7 females) were studied, aged 10 to 18 years, without history of disease or use of medication that could change the suggested laboratory evaluation. On physical examination, the pubertal signs, acanthosis nigricans (AN), weight and height were evaluated. Fasting plasma glucose and insulin were analysed by the colorimetric method and RIA-kit LINCO, respectively. IR was calculated using the HOMA method. The patients were grouped into obese, overweight and normal, according to their BMI percentiles. The EPIINFO 2004 software was used to calculate the BMI, its percentile and Z score.

Results

Five patients were adults (Tanner V or presence of menarche), 9 pubertal (Tanner II – IV) and 1 prepubertal (Tanner I). No one had AN. Two were obese, 4 overweight and 9 normal. Considering the total number of patients, HOMA was 1.7 ± 1.0, insulin 9.3 ± 4.8 μU/ml and glucose 74.4 ± 14.8 mg/dl. The HOMA values were 2.0 ± 1.0 in females and 1.5 ± 1.0 in males. Considering the nutritional classification, the values of HOMA and insulin were: HOMA: 3.3 ± 0.6, 2.0 ± 1.1 and 1.3 ± 0.6, and insulin: 18.15 ± 1.6 μU/ml, 10.3 ± 3.5 μU/ml and 6.8 ± 2.8 μU/ml, in the obese, overweight and normal groups respectively. Considering puberty, the values of HOMA and insulin were: HOMA: 2.5 ± 1.3, 1.4 ± 0.6 and 0.8 ± 0.0, and insulin: 13.0 ± 5.8 μU/ml, 7.8 ± 2.9 μU/ml and 4.0 ± 0.0 μU/ml, in the adult, pubertal and prepubertal groups respectively.

Conclusion

The obese and overweight, female and adult patients showed the highest values of HOMA and insulin.