Intersexual Conflict and Group Size in <Emphasis Type="Italic">Alouatta palliata</Emphasis>: A 23-year Evaluation

Models of optimal primate group size suggest that group formation and growth arise to benefit individual fitness, but that size is limited by costs. The ecological constraints hypothesis posits that group formation and growth is driven by protection from predation or the advantages of group foraging, while an upper limit on group size is constrained by travel costs and intragroup competition for food or other critical resources. Socioecological models also predict that individual reproductive success, hypothesized to decrease with increasing group size, also places an upper limit on the number of individuals in a group. Our analysis of 23 yr of group composition data on mantled howlers (Alouatta palliata) from a single Panamanian study site on Barro Colorado Island not only corroborates the socioecological model but also shows that female reproductive success increased, whereas that of males decreased, with the less female-biased sex ratios in larger groups. We suggest that the conflict of interest between the sexes over adult sex ratio, particularly the male proportion in a group, in combination with ecological factors, is an important determinant of group size and composition.     

Evaluating the Influence of the Presence of a Dog on Bias toward Individuals with Overweight and Obesity

Individuals with overweight and obesity are subject to enormous bias and discrimination across domains. This bias constitutes a considerable public health problem beyond the effects of excess weight on health. Unfortunately, the few interventions that have been implemented to reduce this bias have not been successful. Evidence that the presence of an animal makes individuals and settings appear more attractive, desirable, approachable, and relaxed, as well as happier and safer, suggests that dog ownership may be a simple way to reduce weight bias. Accordingly, we tested whether the presence of a dog can reduce weight bias in a sample of 314 online participants. Each participant was presented with a stimulus image representing one of three conditions (person with dog, person with plant, or person alone), and was then asked to rate the human model using three measures. Two sets of stimuli (featuring different models) were used to ensure that findings were not restricted to a particular model. Contrary to our predictions, we found no evidence that the presence of a dog affects endorsement of weight-related stereotypes, general evaluations, or desire for social distance. These findings contrast with a large body of literature showing that dogs enhance perceptions of a range of individuals and settings. The effect of dogs on perceptions may be restricted in the case of weight bias because of the pervasive, explicit, and severe nature of this bias. Dogs may have stronger effects on attitudes that are less openly endorsed. Promising avenues where dogs are very likely to influence attitudes include perceptions of individuals of different racial and ethnic backgrounds, gender identities, and even political parties.     

Two Cases of Recovery of Dimorphic Pathogenic Fungi via Conventional BacT/ALERT<Superscript>®</Superscript> Microbial Detection System Media

We hereby report two instances of dimorphic fungus cultivation in BacT/ALERT^®-based bacteriologic media, with the first such characterization of Blastomyces dermatitidis. From a patient with disseminated coccidioidomycosis, routine blood cultures incubated on the MB/BacT^® 3D^? Microbial Detection System generated a positive signal following 75 h of incubation. B. dermatitidis was isolated from a patient hospitalized with a four-week course of respiratory illness. Organism detection from respiratory specimens via the MB/BacT^® 3D^? Mycobacteria Detection System occurred 5 days sooner than the routine fungus culture. Etiologic agents of endemic mycoses may be isolated in bacteriologic media employed by continuous monitoring instrumentation.     

Small trees,big problems: Comparative leaf function under extreme edaphic stress

Premise of the Study

The pygmy forest, a plant community of severely stunted conifers and ericaceous angiosperms, occurs on patches of highly acidic, nutrient‐poor soils along the coast of Northern California, USA. This system is an excellent opportunity to study the effect of severe nutrient deficiency on leaf physiology in a naturally‐occurring ecosystem. In this study, we seek to understand the physiological mechanisms stunting the plants' growth and their implications for whole plant function.

Methods

We measured 14 traits pertaining to leaf photosynthetic function or physical structure on seven species. Samples were taken from the pygmy forest community and from conspecifics growing on higher‐nutrient soils, where trees may grow over 30 m tall.

Key Results

Pygmy plants of most species maintained similar area‐based photosynthetic and stomatal conductance rates to conspecific controls, but had lower specific leaf area (leaf area divided by dry weight), lower percent nitrogen, and less leaf area relative to xylem growth. Sequoia sempervirens, a species rare in the pygmy forest, had a categorically different response from the more common plants and had remarkably low photosynthetic rates.

Conclusions

Pygmy plants were not stunted by low photosynthetic rates on a leaf‐area basis; instead, several species had restricted whole‐plant photosynthesis due to low leaf area production. Pygmy plants of all species showed signs of greater carbon investment in their leaves and higher production of nonphotosynthetic leaf tissue, further contributing to slow growth rates.     

Genetic structure of an isolated population of mantled howler monkeys (Alouatta palliata) on Barro Colorado Island, Panama

Habitat fragmentation may influence genetic variability through reductions in population size and the physical isolation of conspecifics. We explored the effects of these factors on genetic diversity in a population of mantled howler monkeys (Alouatta palliata) on Barro Colorado Island (BCI), Panama. The study population was established in 1914 when an unknown number of resident individuals were isolated from the surrounding mainland by damming of the Río Chagres to create the Panama Canal. Analyses of 10 microsatellite loci indicated that, despite this isolation, the howler monkeys on BCI exhibit levels of genetic diversity (H _S = 0.584 ± 0.063) among the highest reported for any species of Alouatta. These data also revealed that although relatedness among adults in a social group was significantly greater than zero, the BCI population is not highly genetically structured. Tests for genetic bottlenecks based on departures from equilibrium expectations failed to reveal evidence of a recent reduction in population size. In contrast, coalescent modeling indicated that this population has likely experienced a marked decline within the last few 100 years. These findings generate new insights into the genetic structure of A. palliata and suggest that while the formation of BCI may not have substantially reduced genetic variation in these animals, genetic diversity has been influenced by historical changes in population size.     

Assembly and characterization of heterochromatin and euchromatin on human artificial chromosomes

Background

Human centromere regions are characterized by the presence of alpha-satellite DNA, replication late in S phase and a heterochromatic appearance. Recent models propose that the centromere is organized into conserved chromatin domains in which chromatin containing CenH3 (centromere-specific H3 variant) at the functional centromere (kinetochore) forms within regions of heterochromatin. To address these models, we assayed formation of heterochromatin and euchromatin on de novo human artificial chromosomes containing alpha-satellite DNA. We also examined the relationship between chromatin composition and replication timing of artificial chromosomes.

Results

Heterochromatin factors (histone H3 lysine 9 methylation and HP1α) were enriched on artificial chromosomes estimated to be larger than 3 Mb in size but depleted on those smaller than 3 Mb. All artificial chromosomes assembled markers of euchromatin (histone H3 lysine 4 methylation), which may partly reflect marker-gene expression. Replication timing studies revealed that the replication timing of artificial chromosomes was heterogeneous. Heterochromatin-depleted artificial chromosomes replicated in early S phase whereas heterochromatin-enriched artificial chromosomes replicated in mid to late S phase.

Conclusions

Centromere regions on human artificial chromosomes and host chromosomes have similar amounts of CenH3 but exhibit highly varying degrees of heterochromatin, suggesting that only a small amount of heterochromatin may be required for centromere function. The formation of euchromatin on all artificial chromosomes demonstrates that they can provide a chromosome context suitable for gene expression. The earlier replication of the heterochromatin-depleted artificial chromosomes suggests that replication late in S phase is not a requirement for centromere function.

     

Discovery and SAR of isonicotinamide BACE-1 inhibitors that bind beta-secretase in a N-terminal 10s-loop down conformation

A series of low-molecular weight 2,6-diamino-isonicotinamide BACE-1 inhibitors containing an amine transition-state isostere were synthesized and shown to be highly potent in both enzymatic and cell-based assays. These inhibitors contain a trans-S,S-methyl cyclopropane P(3) which bind BACE-1 in a 10s-loop down conformation giving rise to highly potent compounds with favorable molecular weight and moderate to high susceptibility to P-glycoprotein (P-gp) efflux.     

Cloning,Overexpression, Purification,and Characterization of the Maleylacetate Reductase from <Emphasis Type="Italic">Sphingobium chlorophenolicum</Emphasis> Strain ATCC 53874

The final enzyme in the pentachlorophenol (PCP) biodegradation pathway in Sphingobium chlorophenolicum is maleylacetate reductase (PcpE), which catalyzes the reductive dehalogenation of 2-chloromaleylacetate to maleylacetate and the subsequent reduction of malyelacetate to 3-oxoadipate. In this study, the pcpE gene was cloned from S. chlorophenolicum strain ATCC 53874 and overexpressed in Escherichia coli BL21-AI cells. The recombinant PcpE, purified to higher than 95% purity using affinity chromatography, exhibited optimal activity at pH 7.0. The kinetic parameters k _cat and K _m were 1.2 ± 0.3 s⁻¹ and 0.09 ± 0.04 mM, respectively, against maleylacetate under the optimal pH. In addition, the purified PcpE was able to restore PCP-degrading capability to S. chlorophenolicum strain ATCC 39723, implicating that there was no functional PcpE in the ATCC 39723 strain.     

Rational design and synthesis of selective BACE-1 inhibitors

An effective approach for enhancing the selectivity of beta-site amyloid precursor protein cleaving enzyme (BACE 1) inhibitors is developed based on the unique features of the S1' pocket of the enzyme. A series of low molecular weight (<600) compounds were synthesized with different moieties at the P1' position. The selectivity of BACE 1 inhibitors versus cathepsin D and renin was enhanced 120-fold by replacing the hydrophobic propyl group with a hydrophilic propionic acid group.