Factors affecting wounding aggression in a colony of captive chimpanzees (Pan troglodytes)

Previous research has suggested that chimpanzees (Pan troglodytes) display higher levels of aggression in captivity than in the wild. One of the challenges of captive management, therefore, is to balance the chimpanzees' need for social interaction with managements' desire to minimize wounding and aggression. Various captive studies have examined the effects of individual and social variables on the frequency of wounding aggression, but none have examined these variables simultaneously. We collected retrospective wounding data for severe wounds from 83 captive chimpanzees (36 males, 47 females) from January 1993 to December 2003. The context of the wounding event, including individual age and sex, group age and sex composition, group duration, and portion of the week (weekday vs. weekend) were collected. Logistic regression analysis was performed to determine which variables had a significant effect on the probability of a severe wounding event. The sex and age composition of the group, group duration, and portion of the week had a statistically significant association with wounding. All‐male groups (Odds Ratio (OR)=6.738) had the highest risk of wounding aggression, with uni‐male groups (OR=3.311) having the next largest. Compared to individuals in all sub‐adult groups, individuals in either all‐adult (OR=4.516) or mixed‐age (OR=3.587) groups had a higher risk of wounding. There was an inverse association between group duration and wounding (OR=0.821). Finally, there was an increased risk of wounding during the work week (OR=1.653). These results suggest that captive management should pay close attention to group composition, as well as levels of human activity, when devising strategies to reduce captive chimpanzee aggression. Zoo Biol 29:351–364, 2010. © 2009 Wiley‐Liss, Inc.     

Excess Weight and the Risk of Incident Coronary Heart Disease Among Men and Women

Overweight and obesity have been prospectively associated with the risk of coronary heart disease (CHD). Less clear is the relation of excess weight to risk of CHD among men and women with comorbid conditions, and the proportion of CHD risk attributable to excess weight in the US population. To assess the risk of CHD associated with excess weight among men and women with and without associated comorbid conditions, and determine the population attributable risk of CHD associated with excess weight. The study population consisted of two prospective cohorts, the Health Professionals Follow‐up Study (HPFS) (N = 42,351 men; age range at baseline, 39–75 years) and the Nurses' Health Study (NHS) (N = 76,703 women; age range at baseline, 39–65 years). A total of 2,771 incident cases of CHD among the men and 2,359 among the women were documented over the 16 years of follow‐up. Overall, the relative risk (RR) of CHD associated with BMI ≥30 kg/m² compared with BMI 18.5–22.9 kg/m² was 2.13 (95% confidence interval (CI), 1.82–2.48) among the men and 2.48 (95% CI, 2.20–2.80) among the women. The risk of CHD increased with BMI, both with and without the presence of comorbid conditions. Our estimates suggest that more than a third of all incident CHD in US men and women may be attributed to excess weight. Excess weight is associated with increased risk of CHD among men and women, both alone and in combination with comorbid conditions, though the results require careful interpretation. A substantial proportion of incident CHD may be attributed to excess weight.     

Dynamic regulation of mammalian numb by G protein-coupled receptors and protein kinase C activation: Structural determinants of numb association with the cortical membrane

The cell fate determinant Numb is a membrane-associated adaptor protein involved in both development and intracellular vesicular trafficking. It has a phosphotyrosine-binding (PTB) domain and COOH-terminal endocytic-binding motifs for alpha-adaptin and Eps15 homology domain-containing proteins. Four isoforms of Numb are expressed in vertebrates, two of which selectively associate with the cortical membrane. In this study, we have characterized a cortical pool of Numb that colocalizes with AP2 and Eps15 at substratum plasma membrane punctae and cortical membrane-associated vesicles. Green fluorescent protein (GFP)-tagged mutants of Numb were used to identify the structural determinants required for localization. In addition to the previously described association of the PTB domain with the plasma membrane, we show that the AP2-binding motifs facilitate the association of Numb with cortical membrane punctae and vesicles. We also show that agonist stimulation of G protein-coupled receptors (GPCRs) that are linked to phospholipase Cbeta and protein kinase C (PKC) activation causes redistribution of Numb from the cortical membrane to the cytosol. This effect is correlated with Numb phosphorylation and an increase in its Triton X-100 solubility. Live-imaging analysis of mutants identified two regions within Numb that are independently responsive to GPCR-mediated lipid hydrolysis and PKC activation: the PTB domain and a region encompassing at least three putative PKC phosphorylation sites. Our data indicate that membrane localization of Numb is dynamically regulated by GPCR-activated phospholipid hydrolysis and PKC-dependent phosphorylation events.     

Preferential induction of IL-10 in APC correlates with a switch from Th1 to Th2 response following infection with a low pathogenic variant of Theiler's virus

Theiler's murine encephalomyelitis virus induces immune-mediated demyelination in susceptible mice after intracerebral inoculation. A naturally occurring, low pathogenic Theiler's murine encephalomyelitis virus variant showed a single amino acid change within a predominant Th epitope from lysine to arginine at position 244 of VP1. This substitution is the only one present in the entire viral capsid proteins. In this paper, we demonstrate that the majority of T cells specific for VP1(233-250) and VP2(74-86) from wild-type virus-infected mice are Th1 type and these VP1-specific cells poorly recognize the variant VP1 epitope (VP1(K244R)) containing the substituted arginine. In contrast, the Th2-type T cell population specific for these epitopes predominates in variant virus-infected mice. Immunization with UV-inactivated virus or VP1 epitope peptides could not duplicate the preferential Th1/Th2 responses following viral infection. Interestingly, the major APC populations, such as dendritic cells and macrophages, produce IL-12 on exposure to the pathogenic wild-type virus, whereas they preferentially produce IL-10 in response to the low pathogenic variant virus. Thus, such a spontaneous mutant virus may have a profoundly different capability to induce Th-type responses via selective production of cytokines involved in T cell differentiation and the consequent pathogenicity of virally induced immune-mediated inflammatory diseases.     

Identification,Purification, and Characterization of Transpeptidase and Glycosyltransferase Domains of Streptococcus pneumoniae Penicillin-Binding Protein 1a

Resistance to β-lactam antibiotics in Streptococcus pneumoniae is due to alteration of penicillin-binding proteins (PBPs). S. pneumoniae PBP 1a belongs to the class A high-molecular-mass PBPs, which harbor transpeptidase (TP) and glycosyltransferase (GT) activities. The GT active site represents a new potential target for the generation of novel nonpenicillin antibiotics. The 683-amino-acid extracellular region of PBP 1a (PBP 1a*) was expressed in Escherichia coli as a GST fusion protein. The GST-PBP 1a* soluble protein was purified, and its domain organization was revealed by limited proteolysis. A protease-resistant fragment spanning Ser 264 to Arg 653 exhibited a reactivity profile against both β-lactams and substrate analogues similar to that of the parent protein. This protein fragment represents the TP domain. The GT domain (Ser 37 to Lys 263) was expressed as a recombinant GST fusion protein. Protection by moenomycin of the GT domain against trypsin degradation was interpreted as an interaction between the GT domain and the moenomycin.The synthesis of the bacterial cell wall requires cytoplasmic and periplasmic enzymes. The final steps of peptidoglycan biosynthesis occur outside the cytoplasmic membrane, and they are catalyzed by membrane-bound penicillin-binding proteins (PBPs). PBPs play essential roles in cell division and morphology (6, 20, 31). Based upon their molecular sizes and amino acid sequence similarities, PBPs can be classified into two groups (6): low-molecular-weight (low-M_r) PBPs, which act as d,d-carboxypeptidases, and high-molecular-weight (high-M_r) PBPs, which carry transpeptidase (TP) and glycosyltransferase (GT) activities. The high-M_r group can be further divided into bifunctional enzymes with TP and GT activities (class A) and monofunctional TP enzymes (class B).β-Lactam antibiotics bind with high affinity specifically to d,d-carboxypeptidase and TP domains because of their structural similarity to the natural substrates, the stem peptides. This binding results in the formation of a covalent acyl-PBP enzyme complex, leading to the inactivation of PBPs.High-M_r PBPs are multidomain proteins (6). The three-dimensional structure of Streptococcus pneumoniae PBP 2x (class B high-M_r PBP) illustrates this domain organization (25). The only non-penicillin-binding domain of known function is the GT domain, corresponding to the N-terminal region of class A PBPs. This GT activity, clearly identified in Escherichia coli PBP 1b, is difficult to measure (23, 29, 31–35). It is insensitive to penicillin but sensitive to moenomycin, an antibiotic which is not used for human therapy (23, 29, 32, 33).S. pneumoniae is one of the major human pathogens of the upper respiratory tract, causing pneumonia, meningitis, and ear infections. Six PBPs have been identified in S. pneumoniae: high-M_r PBPs 1a, 1b, 2a, 2x, and 2b and low-M_r PBP 3 (8). PBPs 1a, 1b, and 2a belong to class A, while PBPs 2x and 2b are monofunctional class B proteins. Deletion of pbp2x and pbp2b in S. pneumoniae is lethal for the bacteria, while the deletion of pbp1a is tolerated (11), probably due to compensation by PBP 1b. This has been observed for E. coli class A PBP 1a, whose deletion can be compensated for by PBP 1b (36). In clinical isolates of resistant pneumococci, pbp1a, pbp2x, and pbp2b genes were shown to present a mosaic organization, encoding PBPs with reduced affinity for β-lactam antibiotics (2, 5, 15, 18). The specific resistance to ceftriaxone and cefotaxime of S. pneumoniae from the hospital environment is mediated by modification of PBP 2x and PBP 1a (22). Furthermore, gene transfer of pbp1a, pbp2x, and pbp2b from resistant strains conferred penicillin resistance on sensitive S. pneumoniae strains under laboratory conditions (2–4, 14, 15, 27, 30).The effort to overcome resistance to antibiotics in S. pneumoniae might therefore benefit from a detailed understanding of the molecular basis of TP and GT activities. The GT domain represents a new potential target for novel nonpenicillin antibiotics. Here, we delineate the GT and TP domains of S. pneumoniae PBP 1a* (a water-soluble form of PBP 1a) by limited proteolytic digestion and expression of recombinant domains. The TP activity of PBP 1a* and that of the isolated TP domain were compared. We also present evidence for an interaction between the isolated GT domain and moenomycin.     

KLEPTOPLASTIDY IN THE TOXIC DINOFLAGELLATE PFIESTERIA PISCICIDA (DINOPHYCEAE)

The ichthyotoxic dinoflagellate Pfiesteria piscicida Steidinger et Burkholder has a complex life cycle with several heterotrophic flagellated and amoeboid stages. A prevalent flagellated form, the nontoxic zoospore stage, has a proficient grazing ability, especially on cryptophyte prey. Although P. piscicida zoospores lack the genetic capability to synthesize chloroplasts, they can obtain functional chloroplasts from algal prey (i.e. kleptoplastidy), as demonstrated here with a cryptophyte prey. Zoospores grown with Rhodomonas sp. Karsten CCMP757 (Cryptophyceae) grazed the cryptophyte population to minimal densities. After placing the cultures in near darkness where cryptophyte recovery was restricted and further prey ingestion did not occur, the time-course patterns in growth, prey chloroplast content·zoospore⁻¹, and prey nucleus content·zoospore⁻¹ were followed. Ingested chloroplasts were selectively retained in the dinoflagellate, as indicated by the decline and, ultimately, near absence of cryptophyte nuclei in plastid-containing zoospores. Chloroplasts retained inside P. piscicida cells for at least a week were photosynthetically active, as indicated by starch accumulation and microscope-autoradiographic measurements of bicarbonate uptake. Recognition that P. piscicida can function as a phototroph broadens our perspective of the physiological ecology of the dinoflagellate because it suggests that, at least during part of its life cycle, P. piscicida 's growth and survival might be affected by photoregulation and nutritional control of photosynthesis.     

THE SEASONAL DISTRIBUTION,ABUNDANCE AND DIVERSITY OF DESMIDS (CHLOROPHYTA) IN A SOFTWATER,NORTH TEMPERATE STREAM1

Suspended and benthic algal communities from a mildly acidic, third-order Rhode Island stream were examined to determine the seasonal distribution, abundance and diversity of the lotic desmids. Within a one-year sampling period, 148 species and 202 subspecific taxa of desmids were identified, representing 23 genera. Species of Cosmarium and Closterium accounted for approximately 70% of the desmids present, and were the most diverse and abundant taxa during all seasons except spring, when Hyalotheca dissiliens was the dominant desmid species. Average abundance and species richness generally were greatest during summer for both suspended and benthic desmids. Most desmids occurred in benthic habitats, and were randomly distributed among substrata. Average seasonal abundance was 7.4 × 10⁴ cells·g^?1 dry wt substratum, among 13 types of substrata. Highest desmid abundance was measured among substrata with intricate morphologies, such as Fontinalis spp., which was associated with 1.2 × 10⁶ desmid cells·g^?1 dry wt substratum, or 1.7 × 10³ cells·cm^?2 substratum. Cell division was observed for 70 desmid taxa, and average seasonal reproduction (based on cell numbers) among all substrata ranged from 4% in winter to 20% during summer. In addition, sexually produced zygospores were found occasionally for H. dissiliens. Desmids were distributed among most substrata examined in this stream, with abundance comparable to reported estimates from softwater lakes and acid bogs. In contrast to established dogma, lotic desmids are not incidental drift organisms, but rather comprise a viable and persistent component of the stream periphyton.