Revisiting Patterns of Tree Species Composition and their Driving Forces in the Atlantic Forests of Southeastern Brazil

The elucidation of phytogeographic patterns and their drivers in biodiversity hotspots is essential to the study of ecology and the conservation of these areas. In 2000, an important study by Oliveira‐Filho and Fontes led to changes in the paradigms that define our understanding of the Atlantic Forest (Brazil). Here, our aim was to revisit this study using a more comprehensive set of environmental predictors, an updated and much larger tree species dataset and checklist, and more refined data analyses. We performed exploratory and confirmatory analyses, including the modeling of the spatial components with Moran's Eigenvector Maps, using data from 483 sites in southeastern Brazil, which encompass a total of 3546 species and 33 geo‐climatic variables. We observed strong floristic similarities between rain‐ and seasonal forests and a species distribution continuum across the main gradients. The environmental and spatial variables were significantly correlated with floristic patterns, and we demonstrated that the tree flora of the seasonal forests should no longer be considered a simple subset of the rain forest flora. The findings of the original paper were not only confirmed but we also unveiled additional, important phytogeographic patterns. We also reinforced the main conclusion of the paper that the Atlantic Forest concept must encompass all of the forest types east of the dry corridor in South America, a designation of utmost importance for the conservation of this biodiversity hotspot.     

Maize Sh2 gene is constrained by natural selection but escaped domestication

In Zea mays L., we studied the molecular evolution of Shrunken2 (Sh2), a gene that encodes the large subunits of a major enzyme in endosperm starch biosynthesis, ADP-glucose pyrophosphorylase. We compared 4669 bp of the Sh2 coding region on 50 accessions of maize and teosinte. Very few nucleotide polymorphisms were found when compared with other genes in Z. mays, revealing an effect of purifying selection in the whole species that predates domestication. Additionally, the comparison of Sh2 sequences in all Z. mays subspecies and outgroups Z. diploperennis and Tripsacum dactyloides suggests the occurrence of an ancient selective sweep in the Sh2 3' region. The amount and nature of nucleotide diversity are similar in both maize and teosinte, confirming previous results that suggested that Sh2 has not been involved in maize domestication. The very low level of nucleotide diversity as well as the highly conserved protein sequence suggest that natural selection retained effective Sh2 allele(s) long before agriculture started, making human selection inefficient on this gene.     

Glucose response to an oral glucose tolerance test predicts weight change in non-diabetic subjects

Objective: Glucose exerts a dual action in the regulation of energy balance, consisting of inhibition of energy intake and stimulation of energy expenditure. Whether blood glucose affects long‐term regulation of body weight in humans remains to be established. We sought to test the hypothesis that the post‐challenge glucose response is a predictor of weight change. Research Methods and Procedures: We performed a prospective analysis of the impact of glucose response to an oral glucose tolerance test (OGTT) and a mixed‐meal test (MT) on subsequent changes in body weight (BW) on 253 Pima Indians (166 men and 87 women) with normal glucose regulation at baseline and follow‐up (follow‐up: 7 ± 4 years). Main outcome measures included BW change (total, percent, and annual), plasma glucose and insulin concentrations during OGTT and MT [total and incremental areas under the curve (AUCs)], resting metabolic rate (RMR; indirect calorimetry), and insulin action (euglycemic‐hyperinsulinemic clamp). Results: Total and incremental glucose AUCs during the OGTT (but not the MT) were negatively associated with BW change (total, percent, and annual), both before and after adjusting for sex, age, initial BW, follow‐up time, insulin action, RMR, fasting plasma glucose and insulin concentrations, and insulin response. Total and incremental glucose AUCs during the OGTT were independent determinants of final BW with age, initial BW, follow‐up time, fasting plasma insulin concentrations, and RMR. Discussion: Higher post‐challenge glucose response protects against BW gain in subjects with normal glucose regulation. We propose that this action may be because of the effect of glucose on food intake and/or thermogenesis.     

Principal Predictors and Efficiency in Small Second-Order Designs

Linear parametric functions affected by deleting or augmenting sets of design points are identified explicitly using principal components of the predictive dispersion at those points, offering fresh insight and significant computational savings. Leverages from regression diagnostics are seen to determine efficiencies due to augmenting or deleting single points. Eight small second-order designs are studied in detail with supporting numerical displays. Comparisons are drawn to other approaches from the literature.     

Dosage regulation of Zea mays homeobox (ZmHox) genes and their relationship with the dosage-sensitive regulatory factors of Shrunken 1 (Sh1) in maize

In gene dosage studies on the expression of the maize Shrunken I gene several dosage-sensitive regulatory factors were identified that modulate Sh 1 mRNA levels in various aneuploids. ZmHox 1a and 1b have been shown to interact with the Sh1 promoter sequences in vitro. The present study was conducted to test whether these molecularly defined regulatory genes are subject to dosage modulation and to determine whether ZmHox 1a and 1b are involved with the dosage sensitive modification of Sh1 expression. The result was that ZmHox 1a and 1b were affected by several transacting dosage modifiers and that both genes exhibited a structural gene dosage effect but did not modulate Sh1 mRNA levels. For some chromosomal regions, a correlation was found between the dosage regulation of Sh1 and that of ZmHox 1a, while other effects were not correlated. The results suggest that the dosage effects on Sh1 are not mediated by ZmHox 1a or 1b, but interestingly Sh1 and ZmHox 1a share some dosage-regulatory effects. Dev Genet 20:67–73, 1997. © 1997 Wiley-Liss, Inc.     

Relationships between Insulin Sensitivity and Measures of Body Fat in Asymptomatic Men and Women

Objective: To assess whether measures of body fat by DXA scanning can improve prediction of insulin sensitivity (S_I) beyond what is possible with traditional measures, such as BMI, waist circumference, and waist‐to‐hip ratio (WHR). Research Methods and Procedures: Frequently sampled intravenous glucose tolerance tests were performed in 256 asymptomatic non‐Hispanic white subjects from Rochester, MN (age 19‐60 years; 123 men and 133 women) to determine the S_I index by Bergman's minimal model technique. Height, weight, and waist and hip circumferences were measured for calculation of BMI and WHR; DXA was used to determine fat in the head, upper body, abdomen, and lower body. Linear regression was used to assess their relationships with S_I after sex stratification and adjustment for age. Results: After controlling for age, increases in traditional and DXA measures of fat were consistently associated with smaller declines in S_I among women than among men. In men, after controlling for age, all of the predictive information of S_I was provided by waist circumference (additional R² = 0.39, p < 0.001); none of the DXA measures improved the ability to predict S_I. In women, after adjustment for age, BMI, and WHR, the only DXA measure that improved the prediction of S_I was percentage head fat (additional R² = 0.03, p < 0.001). Discussion: Equivalent increases in most measures of body fat had lesser impact on S_I in women than in men. In both sexes, the predictive information provided by DXA measures is approximately equal to, but not additive to, that provided by simpler, traditional measures.     

A statistical investigation of amphiphilic properties of C-terminally anchored peptidases

A number of DD-peptidases have been reported to interact with the membrane via C-terminal amphiphilic α-helices, but experimental support for this rests with a few well-characterized cases. These show the C-terminal interactions of DD-carboxypeptidases to involve high levels of membrane penetration, DD-endopeptidases to involve membrane surface binding and class C penicillin-binding proteins to involve membrane binding with intermediate properties. Here, we have characterized C-terminal α-helices from each of these peptidase groups according to their amphiphilicity, as measured by mean <μH>, and the corresponding mean hydrophobicity, <H>. Regression and statistical analyses showed these properties to exhibit parallel negative linear relationships, which resulted from the spatial ordering of α-helix amino acid residues. Taken with the results of compositional and graphical analyses, our results suggest that the use of C-terminal α-helices may be a universal feature of the membrane anchoring for each of these groups of DD-peptidases. Moreover, to accommodate differences between these mechanisms, each group of C-terminal α-helices optimizes its structural amphiphilicity and hydrophobicity to fulfil its individual membrane-anchoring function. Our results also show that each anchor type analysed requires a similar overall balance between amphiphilicity for membrane interaction, which we propose is necessary to stabilize their initial membrane associations. In addition, we present a methodology for the prediction of C-terminal α-helical anchors from the classes of DD-peptidases analysed, based on a parallel linear model.     

Group size, sex and age composition of chital (Axis axis) and sambar (Rusa unicolor) in a deciduous habitat of Western Ghats

Knowledge of the social structure of a population is important for a range of fundamental and applied purposes. Group characteristics and population structure of chital (Axis axis) and sambar (Rusa unicolor) were studied in a deciduous habitat of Mudumalai Tiger Reserve, Western Ghats, India, during 2008-2009. Vehicle transects were monitored monthly to gather information on group-size and age-sex composition of chital and sambar. The average mean group size and crowding for chital and sambar was 13.1 ± 0.5 (n = 1020), 3.6 ± 0.2 (n = 377) and 33.3, 11.0 respectively. The average adult male:adult female:fawn ratio was 63.4:100:22.3 (n = 9391) and 43.9:100:23.7 (n = 1023) in chital and sambar respectively. The mean group size of chital and sambar varied significantly between seasons (Kruskal-Wallis test, p = <0.001). Peak fawning season was observed from February to May for chital and May to August for sambar. Group's sex-age composition influenced group formation in both species between seasons at different level. Adult male and fawn were the important predicting variables of change in group size. Skewed female sex ratio was probably due to selective male predation by large predators. Although fawning occurred throughout the year, both species showed seasonality in fawning. The above mentioned patterns differed between species depending upon their ecological adaptation in foraging strategies and habitat preference.     

Do Psychosocial Variables Predict Weight Loss or Mental Health after Obesity Surgery? A Systematic Review

Objective: The objective of this study was to present a systematic review of psychological and psychosocial predictors of weight loss and mental health after bariatric surgery. This systematic review included all controlled and noncontrolled trials of the last 2 decades with either a retrospective or prospective design and a follow‐up period of at least 1 year. Research Methods and Procedures: The relevant literature was identified by a search of computerized databases. All articles published in English and German between 1980 and 2002 were reviewed. Results: Using the above inclusion/exclusion criteria, 29 articles were identified focusing on psychosocial predictors of weight loss and mental health after obesity surgery. Discussion: Personality traits have no predictive value for the postoperative course of weight or mental state. Apart from serious psychiatric disorders including personality disorders, psychiatric comorbidity seems to be of more predictive value for mental and physical well‐being as two essential aspects of quality of life than for weight loss postsurgery. However, depressive and anxiety symptoms as correlates of psychological stress with regard to obesity seem to be positive predictors of weight loss postsurgery. The severity of the symptoms or the disorder is more relevant for the outcome of obesity surgery than the specificity of the symptoms. It is also not solely the consumption of distinct “forbidden” foods, such as sweets or soft drinks, but rather a general hypercaloric eating behavior, either as an expression of the patient's inadequate compliance or a dysregulation in energy balance, which is associated with a poor weight loss postsurgery.     

Predictors for Seasonal and Nonseasonal Fractionally Integrated ARIMA Models

This paper derives easy-to-calculate preditors for seasonal and nonseasonal fractionally integrated autoregressive-moving average (ARIMA (p, d, q) × (P, D, Q)_s) models with both differencing parameters d and D assuming values on the real line. It is shown that these predictors are optimum. Special attention is given to the one-step-ahead predictors as they are constantly in demand in almost every practical situation.