The meaning of weaning in wild Phayre's leaf monkeys: Last nipple contact,survival, and independence

In primates and other mammals, weaning is an equivocal concept, as is reflected in the numerous ways it is measured: a) first intake of solid food, b) conflict over access to the nipple, c) ability to survive without mother, d) maternal resumption of cycling, or e) the cessation of nipple contact. The lack of a consistent definition means that weaning age, although it falls between gestation (fetal growth) and age at first reproduction (most energy diverted from growth), is currently not a reliable life history variable capturing offspring independence. Using data for wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) at Phu Khieo Wildlife Sanctuary, Thailand (51 offspring, four groups), we asked whether the end of nipple contact indicates offspring independence as measured by survival to 3 years. To establish a baseline for the onset of independence, we assessed the youngest age at which individuals were orphaned (15–17 months) but then survived to 3 years. Next we determined that offspring age at last nipple contact (19.0 months) was comparable to two other independently calculated measures: offspring age at mother's first postpartum ovulation (11.5 months), and age at mother's re‐conception (15.6 months). Using these separate “starting points,” we arrived at similar ages for nipple contact cessation (18.4 and 19.2 months, respectively). Overall, in wild (but not in provisioned) Asian colobines, age at last nipple contact was allometrically related to adult female body mass, supporting its designation as a life history variable. Future comparisons need to show if this holds for other taxa. Am J Phys Anthropol 154:291–301, 2014. © 2014 Wiley Periodicals, Inc.     

Preformed GroES Oligomers Are Not Required as Functional Cochaperonins

We have previously shown that the C-terminal sequence of GroES is required for oligomerization [Seale and Horowitz (1995), J. Biol. Chem. 270, 30268–30270]. In this report, we have generated a C-terminal deletion mutant of GroES with a significantly destabilized oligomer and have investigated its function in the chaperonin-assisted protein folding cycle. Removal of the two C-terminal residues of GroES results in a cochaperonin [GroESD(96–97)] that is monomeric at concentrations where GroES function is assessed. Using equilibrium ultracentrifugation, we measured the dissociation constant for the oligomer–monomer equilibrium to be 7.3×10^–34M⁶. The GroESD(96–97) is fully active as a cochaperonin. This mutant is able to inhibit the ATPase activity of GroEL to levels comparable to wild-type GroES. It is also able to assist the refolding of urea-denatured rhodanese by GroEL. While GroESD(96–97) can function at levels comparable to wild-type GroES, higher concentrations of mutant are required to produce the same effect. These results support the idea that the preformed GroES heptamer is not required for function, but they suggest that the oligomeric cochaperonin is most efficient.     

Structural Characterization of the Extracellular Domain of CASPR2 and Insights into Its Association with the Novel Ligand Contactin1

Contactin-associated protein-like 2 (CNTNAP2) encodes for CASPR2, a multidomain single transmembrane protein belonging to the neurexin superfamily that has been implicated in a broad range of human phenotypes including autism and language impairment. Using a combination of biophysical techniques, including small angle x-ray scattering, single particle electron microscopy, analytical ultracentrifugation, and bio-layer interferometry, we present novel structural and functional data that relate the architecture of the extracellular domain of CASPR2 to a previously unknown ligand, Contactin1 (CNTN1). Structurally, CASPR2 is highly glycosylated and has an overall compact architecture. Functionally, we show that CASPR2 associates with micromolar affinity with CNTN1 but, under the same conditions, it does not interact with any of the other members of the contactin family. Moreover, by using dissociated hippocampal neurons we show that microbeads loaded with CASPR2, but not with a deletion mutant, co-localize with transfected CNTN1, suggesting that CNTN1 is an endogenous ligand for CASPR2. These data provide novel insights into the structure and function of CASPR2, suggesting a complex role of CASPR2 in the nervous system.     

Improved Large-Scale Preparation of Phage T4 Endonuclease VII Overexpressed in E. coli

Using PCR, we cloned T4 gene 49, which encodes the endonucleaseVII, and the inactive mutant gene 49 amE727 into vector pET-11a.In combination with Escherichia coli host strain BL21(DE3),this system provided excellent repression of the expressionof the highly toxic protein before induction with IPTG. Afterinduction, the proteins were made in high quantities while remainingsoluble. Dilution of the crude lysate at 1 : 10,000 continuedto show a highly specific activity in the case of the wild-typeenzyme. The protein was purified to homogeneity with a recoveryof 33% using two chromatography steps. The yield was 20 timeshigher and the specific activity 500 times higher than thatobtained by using the previously published protocol.