Ground‐nesting by the chimpanzees of the Nimba Mountains,Guinea: environmentally or socially determined?

The chimpanzees (Pan troglodytes verus) of the Nimba Mountains, Guinea, West Africa, commonly make both elaborate ("night") and simple ("day") nests on the ground. In this study we investigated which factors might influence ground-nesting in this population, and tested two ecological hypotheses: 1) climatic conditions, such as high wind speeds at high altitudes, may deter chimpanzees from nesting in trees; and 2) a lack of appropriate arboreal nesting opportunities may drive the chimpanzees to nest on the ground. In addition to testing these two hypotheses, we explored whether ground-nesting is a sex-linked behavior. Data were collected monthly between August 2003 and May 2004 along transects and ad libitum. To identify the sex of ground-nesting individuals, we used DNA extracted from hair samples. The results showed that the occurrence and distribution of ground nests were not affected by climatic conditions or a lack of appropriate nest trees. Support was found for the notion that ground-nesting is a sex-linked behavior, as males were responsible for building all of the elaborate ground nests and most of the simple ground nests sampled. Elaborate ground nests occurred mostly in nest groups associated with tree nests, whereas simple ground nests usually occurred without tree nests in their vicinity. These results suggest that ground-nesting may be socially, rather than ecologically, determined.     

Design, synthesis, and evaluation of gamma-phosphono diester analogues of glutamate as highly potent inhibitors and active site probes of gamma-glutamyl transpeptidase

Gamma-glutamyl transpeptidase (GGT, EC 2.3.2.2) catalyzes the transfer of the gamma-glutamyl group of glutathione and related gamma-glutamyl amides to water (hydrolysis) or to amino acids and peptides (transpeptidation) and plays a central role in glutathione metabolism. GGT is involved in a number of biological events, such as drug resistance and metastasis of cancer cells by detoxification of xenobiotics and reactive oxygen species through glutathione metabolism, and is also implicated in physiological disorders, such as Parkinson's disease, neurodegerative disease, diabetes, and cardiovascular diseases. In this study, we designed, synthesized, and evaluated a series of gamma-phosphono diester analogues of glutamate as transition-state mimic inhibitors of GGT. The electrophilic phosphonate diesters served as highly potent mechanism-based inhibitors that caused the time-dependent and irreversible inhibition of both the E. coli and human enzymes, probably by phosphonylating the catalytic Thr residue of the enzyme. In particular, one of the inhibitors exhibited more than 6000 times higher activity toward human GGT than acivicin, a classical but nonselective inhibitor of GGT. The dependence of the inactivation rate on the leaving group ability of the phosphonates (Br?nsted plot) revealed that the phosphonylation of the catalytic Thr residue proceeded via a dissociative transition-state with substantial bond cleavage between the phosphorus and the leaving group for both E. coli and human GGTs. The binding site of GGT for the Cys-Gly moiety of glutathione or for the acceptor molecules was probed by the phosphonate diesters to reveal a significant difference in the mechanism of substrate recognition between E. coli and human GGT. Thus, in the human enzyme, a specific residue in the Cys-Gly binding site played a critical role in recognizing the Cys-Gly moiety or the acceptor molecules by interacting with the C-terminal carboxy group, whereas the Cys side chain and the Cys-Gly amide bond were not recognized significantly. In contrast, the E. coli enzyme was a nonselective enzyme that accommodated substrates without specifically recognizing the C-terminal carboxy group of the Cys-Gly moiety of gamma-glutamyl compounds or the acceptor molecules. The phosphonate diester-based GGT inhibitors shown here should serve as a blue print for the future design of highly selective GGT inhibitors for use as drug leads and biological probes that gain insight into the hitherto undefined physiological roles of GGT and the relationships between GGT and a variety of diseases.     

The genes influencing adiponectin levels also influence risk factors for metabolic syndrome and type 2 diabetes

Results from previous studies suggest that adiponectin levels are associated with risk factors for cardiovascular disease and type 2 diabetes mellitus; however, the genetic and/or environmental components of this relationship have not been characterized. The aims of this study were (1) to assess the presence of pleiotropy between adiponectin levels and risk factors for cardiovascular disease and (2) to study the association of circulating levels of adiponectin with risk factors for cardiovascular disease in the absence and presence of obesity in Mexican American adults from the San Antonio Family Heart Study. Body composition and circulating levels of adiponectin, leptin, and lipid subfractions and measurements of glucose metabolism were measured in 898 subjects. The mean and standard error of the circulating levels of adiponectin was 8.7 +/- 3.2 microg/ml. Bivariate quantitative analyses between adiponectin levels and phenotypes related to cardiovascular disease and type 2 diabetes mellitus were conducted using the variance decomposition approach implemented in SOLAR. A second analysis in unrelated subjects compared these risk factors between sex- and age-matched lean and obese subjects with high and low adiponectin levels. We found significant evidence of pleiotropy (i.e., shared genetic effects) between plasma levels of adiponectin and well-established risk factors for cardiovascular disease and type 2 diabetes mellitus. Individuals with low adiponectin levels per body weight had more adverse risk profiles. These findings offer new insights into the genetic connection between increasing adiposity and risk for cardiovascular disease and type 2 diabetes mellitus, and they suggest that adiponectin may be an important risk factor for the development of these conditions.     

An expeditious synthesis of tamoxifen, a representative SERM (selective estrogen receptor modulator), via the three-component coupling reaction among aromatic aldehyde, cinnamyltrimethylsilane, and beta-chlorophenetole

Two new synthetic pathways to the anti-cancer agent tamoxifen and its derivatives were developed. The first route involved the aldol reaction of benzyl phenyl ketone with acetaldehyde followed by Friedel–Crafts substitution with anisole in the presence of Cl₂Si(OTf)₂ to produce 1,1,2-triaryl-3-acetoxybutane, a precursor of the tamoxifen derivatives. The second one utilized the novel three-component coupling reaction among aromatic aldehydes, cinnamyltrimethylsilane, and aromatic nucleophiles using HfCl₄ as a Lewis acid catalyst to produce 3,4,4-triarylbutene, that is also a valuable intermediate of the tamoxifen derivatives. The former strategy requires a total of 10 steps from the aldol formation to the final conversion to tamoxifen, whereas the latter needs only three or four steps to produce tamoxifen and droloxifene including the installation of the side-chain moiety and the base-induced double-bond migration to form the tetra-substituted olefin structure. This synthetic strategy seems to serve as a new and practical pathway to prepare not only the tamoxifen derivatives but also the other SERMs (selective estrogen receptor modulators) including estrogen-dependent breast cancer and osteoporosis agents.     

Phosphorylation-induced conformational switching of CPI-17 produces a potent myosin phosphatase inhibitor

Phosphorylation of endogenous inhibitor proteins for type-1 Ser/Thr phosphatase (PP1) provides a mechanism for reciprocal coordination of kinase and phosphatase activities. A myosin phosphatase inhibitor protein CPI-17 is phosphorylated at Thr38 through G-protein-mediated signals, resulting in a >1000-fold increase in inhibitory potency. We show here the solution NMR structure of phospho-T38-CPI-17 with rmsd of 0.36 +/- 0.06 A for the backbone secondary structure, which reveals how phosphorylation triggers a conformational change and exposes an inhibitory surface. This active conformation is stabilized by the formation of a hydrophobic core of intercalated side chains, which is not formed in a phospho-mimetic D38 form of CPI-17. Thus, the profound increase in potency of CPI-17 arises from phosphorylation, conformational change, and hydrophobic stabilization of a rigid structure that poses the phosphorylated residue on the protein surface and restricts its hydrolysis by myosin phosphatase. Our results provide structural insights into transduction of kinase signals by PP1 inhibitor proteins.     

Novel fluorescent sensing system for alpha-fructosyl amino acids based on engineered fructosyl amino acid binding protein

A novel fluorescent sensing system for alpha-glycated amino acids was created based on fructosyl amino acid binding protein (FABP) from Agrobacterium tumefaciens. The protein was found to bind specifically to the alpha-glycated amino acids fructosyl glutamine (Fru-Gln) and fructosyl valine (Fru-Val) while not binding to epsilon-fructosyl lysine. An Ile166Cys mutant of FABP was created by genetic engineering and modified with the environmentally sensitive fluorophore acrylodan. The acrylodan-conjugated mutant FABP showed eight-fold greater sensitivity to Fru-Val than the unconjugated protein and could detect concentrations as low as 17 nM, making it over 100-fold more sensitive than enzyme-based detection systems. Its high sensitivity and specificity for alpha-substituted fructosyl amino acids makes the new sensing system ideally suited for the measurement of hemoglobin A1c (HbA1c), a major marker of diabetes.     

Effects of adiponectin on the renal sympathetic nerve activity and blood pressure in rats

Adiponectin is an adipocytokine that modulates energy homeostasis and glucose metabolism. Here, we examined the effects of acute intravenous (iv) and lateral cerebral ventricular (LCV) injections of adiponectin on the renal sympathetic nerve activity (RSNA) and blood pressure (b/p) in urethane-anesthetized rats. Both iv and LCV injections of adiponectin induced dose-dependent suppressions of RSNA and b/p. Moreover, we found that bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) abolished the effects of iv injection of adiponectin on RSNA and b/p. These findings suggest that adiponectin decreases the RSNA and b/p in a dose-dependent manner and that the SCN is implicated in mechanism of adiponectin actions on RSNA and b/p. These findings also suggest that the hypotensive-action activity of adiponectin is realized, at least partially, via changes in activities of autonomic nerves activity.     

Effects of magnesium sulfate on the luminescence of Vibrio fischeri under nutrient-starved conditions

In this study, we investigated the relationship between MgSO(4) and luminescence in Vibrio fischeri under nutrient-starved conditions. When V. fischeri was cultured in an artificial seawater medium, the luminescence intensity was low relative to that observed under normal growth conditions. It decreased during the initial 14 h, and then increased slightly at 24 h. This regulation of luminescence was not dependent on the quorum-sensing mechanism, because the cell densities had not reached a critical threshold concentration. Under MgSO(4)-starved conditions, luminescence was not fully induced at 14 h, and decreased at 24 h. In contrast, induction of luminescence occurred under MgSO(4)-supplemented conditions, but MgSO(4) alone was insufficient to induce luminescence, and required NaHCO(3) or KCl. These results suggest that the luminescence of V. fischeri is controlled by an exogenous sulfur source under nutrient-starved conditions. In addition, they indicate that the induction of sulfur-dependent luminescence is regulated by the NaHCO(3) or KCl concentration.     

Numb controls E-cadherin endocytosis through p120 catenin with aPKC

Cadherin trafficking controls tissue morphogenesis and cell polarity. The endocytic adaptor Numb participates in apicobasal polarity by acting on intercellular adhesions in epithelial cells. However, it remains largely unknown how Numb controls cadherin-based adhesion. Here, we found that Numb directly interacted with p120 catenin (p120), which is known to interact with E-cadherin and prevent its internalization. Numb accumulated at intercellular adhesion sites and the apical membrane in epithelial cells. Depletion of Numb impaired E-cadherin internalization, whereas depletion of p120 accelerated internalization. Expression of the Numb-binding fragment of p120 inhibited E-cadherin internalization in a dominant-negative fashion, indicating that Numb interacts with the E-cadherin/p120 complex and promotes E-cadherin endocytosis. Impairment of Numb induced mislocalization of E-cadherin from the lateral membrane to the apical membrane. Atypical protein kinase C (aPKC), a member of the PAR complex, phosphorylated Numb and inhibited its association with p120 and α-adaptin. Depletion or inhibition of aPKC accelerated E-cadherin internalization. Wild-type Numb restored E-cadherin internalization in the Numb-depleted cells, whereas a phosphomimetic mutant or a mutant with defective α-adaptin-binding ability did not restore the internalization. Thus, we propose that aPKC phosphorylates Numb to prevent its binding to p120 and α-adaptin, thereby attenuating E-cadherin endocytosis to maintain apicobasal polarity.     

The oncometabolite 2-hydroxyglutarate inhibits histone lysine demethylases

Mutations in isocitrate dehydrogenases (IDHs) have a gain-of-function effect leading to R(−)-2-hydroxyglutarate (R-2HG) accumulation. By using biochemical, structural and cellular assays, we show that either or both R- and S-2HG inhibit 2-oxoglutarate (2OG)-dependent oxygenases with varying potencies. Half-maximal inhibitory concentration (IC₅₀) values for the R-form of 2HG varied from approximately 25 μM for the histone N^ɛ-lysine demethylase JMJD2A to more than 5 mM for the hypoxia-inducible factor (HIF) prolyl hydroxylase. The results indicate that candidate oncogenic pathways in IDH-associated malignancy should include those that are regulated by other 2OG oxygenases than HIF hydroxylases, in particular those involving the regulation of histone methylation.