Growth and Development in Wild Owl Monkeys (<Emphasis Type="Italic">Aotus azarai</Emphasis>) of Argentina

Life history predicts that in sexually dimorphic species in which males are the larger sex, males should reach sexual maturity later than females (or vice versa if females are the larger sex). The corresponding prediction that in sexually monomorphic species maturational rates will differ little between the sexes has rarely been tested. We report here sex differences in growth and development to adulthood for 70 female and 69 male wild owl monkeys (Aotus azarai). In addition, using evidence from natal dispersal and first reproduction (mean: 74 mo) for 7 individuals of known age, we assigned ages to categories: infant, 0–6 mo; juvenile, 6.1–24 mo; subadult, 24.1–48 mo; adult >48 mo. We compared von Bertalanffy growth curves and growth rates derived from linear piecewise regressions for juvenile and subadult females and males. Growth rates did not differ between the sexes, although juvenile females were slightly longer than males. Females reached maximum maxillary canine height at ca. 2 yr, about a year earlier than males, and females’ maxillary canines were shorter than males’. Thus apart from canine eruption and possibly crown–rump length, the development of Azara’s owl monkeys conforms to the prediction by life history that in monomorphic species the sexes should develop at similar paces.     

Proximate mechanisms of reproductive monopolization in male moustached tamarins (Saguinus mystax)

In moustached tamarin (Saguinus mystax) groups, the single breeding female mates polyandrously with most or all nonrelated adult males. Nonetheless, paternity is monopolized in many groups by a single male. No evidence for male endocrine suppression has been found in this species. The proximate mechanisms of monopolization thus remain poorly understood. The aim of this study was to investigate the possible impact of agonistic interactions and mate-guarding on the monopolization of paternity in male moustached tamarins. Furthermore, we evaluated the likely costs of these behaviors, and whether olfactory cues might be used for its timing. We used behavioral data on proximity, agonistic interactions, time budgets, and scent-marking behavior to answer these questions. While direct agonistic competition does not play a prominent role, fertile females were consorted in some periods by one male, the sire of the previous and next litter. Consorting was instigated nearly exclusively by the male. It probably occurred during the female's periods of highest fertility, and thus likely functions as mate-guarding. The timing of the consortship was probably guided by olfactory cues in the female's scent marks. While we did not obtain direct evidence for energy costs in terms of increased energy expenditure or decreased food intake, we found that consorting males are more conspicuous and therefore may be more vulnerable to predators.     

The immunoglobulin-superfamily molecule basigin is a binding protein for oligomannosidic carbohydrates: an anti-idiotypic approach

Recognition molecules that carry carbohydrate structures regulate cell interactions during development and play important roles in synaptic plasticity and regeneration in the adult. Glycans appear to be involved in these interactions. We have searched for binding proteins for oligomannosidic structures using the L3 antibody directed against high mannose-type glycans in an anti-idiotypic approach. A selected monoclonal anti-idiotype antibody was used for affinity chromatography and identified basigin as a binding protein from mouse brain detergent lysates. Basigin was found to bind to high mannose-carrying cell recognition molecules, such as myelin-associated glycoprotein, L1, the beta2-subunit of Na+/K+-ATPase and an oligomannosidic neoglycolipid. Furthermore, basigin was involved in outgrowth of astrocytic processes in vitro. A striking homology between the first immunoglobulin (Ig)-like domain of basigin and the fourth Ig-like domain of NCAM, previously shown to bind to oligomannosidic glycans, and the lectin domain of the mannose receptor confirms that basigin is an oligomannose binding lectin. To our knowledge this is the first report that anti-idiotypic antibodies can be used to identify binding partners for carbohydrates.     

Essential role of the apolipoprotein E receptor-2 in sperm development

The apolipoprotein (apo) E receptor-2 (apoER2) is a member of the low density lipoprotein receptor gene family and an important regulator of neuronal migration. It acts as a receptor for the signaling factor Reelin and provides positional cues to neurons that migrate to their proper position in the developing brain. Besides brain formation defects, apoER2-deficient mice also exhibit male infertility. The role of the receptor in male reproduction, however, remained unclear. Here we demonstrate that apoER2 is highly expressed in the initial segment of the epididymis, where it affects the functional expression of clusterin and phospholipid hydroperoxide glutathione peroxidase (PHGPx), two proteins required for sperm maturation. Reduced PHGPx expression in apoER2 knockout mice results in the inability of the sperm to regulate the cell volume and in abnormal sperm morphology and immotility. Because insufficient expression of PHGPx is a major cause of infertility in men, these findings not only highlight an important new function for apoER2 that is unrelated to neuronal migration, but they also suggest a possible role for apoER2 in human infertility.     

A novel conus peptide ligand for K+ channels

Voltage-gated ion channels determine the membrane excitability of cells. Although many Conus peptides that interact with voltage-gated Na(+) and Ca(2+) channels have been characterized, relatively few have been identified that interact with K(+) channels. We describe a novel Conus peptide that interacts with the Shaker K(+) channel, kappaM-conotoxin RIIIK from Conus radiatus. The peptide was chemically synthesized. Although kappaM-conotoxin RIIIK is structurally similar to the mu-conotoxins that are sodium channel blockers, it does not affect any of the sodium channels tested, but blocks Shaker K(+) channels. Studies using Shaker K(+) channel mutants with single residue substitutions reveal that the peptide interacts with the pore region of the channel. Introduction of a negative charge at residue 427 (K427D) greatly increases the affinity of the toxin, whereas the substitutions at two other residues, Phe(425) and Thr(449), drastically reduced toxin affinity. Based on the Shaker results, a teleost homolog of the Shaker K(+) channel, TSha1 was identified as a kappaM-conotoxin RIIIK target. Binding of kappaM-conotoxin RIIIK is state-dependent, with an IC(50) of 20 nm for the closed state and 60 nm at 0 mV for the open state of TSha1 channels.     

Nitric oxide synthase II in rat skeletal muscles

Constitutive expression of nitric oxide synthase (NOS) II was found in rat hindlimb muscles by immunohistochemistry and western blotting during development from embryonic day 21 to the adult stage of 75 days. The immunohistochemical NOS II expression pattern was related to the physiological metabolic fibre types SO (slow-oxidative), FOG I, II (fast-oxidative glycolytic; I more glycolytic, II more oxidative) and FG (fast-glycolytic) and to the myosin-based fibre types I and IIA, IIB (IIX not separated) identified in serial sections by enzyme histochemistry and immunohistochemistry. In adult muscles only the small population of FOG II fibres, which is a part of both IIA and IIB fibre population, showed NOS II immunoreactivity. This is the reason that only weak NOS II expression in adult hindlimb muscles has been detected by western blotting. Hindlimb muscles of embryonic, neonatal and young rats of 8 days expressed more NOS II as compared with adult rat hindlimb muscles. This can be explained by the findings that before the age of 21 days fast fibres were metabolically undifferentiated, all of them were NOS II positive and contribute to the NOS II expression of the muscle. In muscles of diabetic rats the NOS II expression was elevated indicating an inhibition of glucose uptake into the muscle fibres of diabetic muscles. Our findings suggest that the NOS II may be designated both as constitutive and inducible.