Female reproduction bears no survival cost in captivity for gray mouse lemurs

The survival cost of reproduction has been revealed in many free‐ranging vertebrates. However, recent studies on captive populations failed to detect this cost. Theoretically, this lack of survival/reproduction trade‐off is expected when resources are not limiting, but these studies may have failed to detect the cost, as they may not have fully accounted for potential confounding effects, in particular interindividual heterogeneity. Here, we investigated the effects of current and past reproductive effort on later survival in captive females of a small primate, the gray mouse lemur. Survival analyses showed no cost of reproduction in females; and the pattern was even in the opposite direction: the higher the reproductive effort, the higher the chances of survival until the next reproductive event. These conclusions hold even while accounting for interindividual heterogeneity. In agreement with aforementioned studies on captive vertebrates, these results remind us that reproduction is expected to be traded against body maintenance and the survival prospect only when resources are so limiting that they induce an allocation trade‐off. Thus, the cost of reproduction has a major extrinsic component driven by environmental conditions.     

An AP site can protect against the mutagenic potential of 8-oxoG when present within a tandem clustered site in E. coli

Ionizing radiation induces clustered DNA damaged sites, defined as two or more lesions formed within one or two helical turns of the DNA through passage of a single radiation track. It is now established that clustered DNA damage sites are found in cells and present a challenge to the repair machinery of the cell but to date, most studies have investigated the effects of bi-stranded lesions. A subset of clustered DNA damaged sites exist in which two or more lesions are present in tandem on the same DNA strand. In this study synthetic oligonucleotides containing an AP site 1, 3 or 5 bases 5' or 3' to 8-oxo-7,8-dihydroguanine (8-oxoG) on the same DNA strand were synthesized as a model of a tandem clustered damaged sites. It was found that 8-oxoG retards the incision of the AP site by exonuclease III (Xth) and formamidopyrimidine DNA glycosylase (Fpg). In addition the rejoining of the AP site by xrs5 nuclear extracts is impaired by the presence of 8-oxoG. The mutation frequency arising from 8-oxoG within a tandem clustered site was determined in both wild type and mutant E. coli backgrounds. In wild-type, nth, fpg and mutY null E. coli, the mutation frequency is slightly elevated when an AP site is in tandem to 8-oxoG, compared with when 8-oxoG is present as a single lesion. Interestingly, in the double mutant mutY/fpg null E. coli, the mutation frequency of 8-oxoG is reduced when an AP site is present in tandem compared with when 8-oxoG is present as a single lesion. This study demonstrates that tandem lesions can present a challenge to the repair machinery of the cell.     

Polymorphisms in the CNTF and CNTF receptor genes are associated with muscle strength in men and women.

Genotypic associations between polymorphisms in the ciliary neurotrophic factor (CNTF) and CNTF receptor (CNTFR) genes and muscular strength phenotypes in 154 middle-aged men (45-49 yr) and 138 women (38-44 yr) and 99 older men (60-78 yr) and 102 older women (60-80 yr) were tested to validate earlier association studies. Allelic interaction effects were hypothesized between alleles of CNTF and CNTFR. We performed analysis of covariance with age, height, and fat-free mass (FFM) as covariates. FFM was anthropometrically estimated by the equation of Durnin-Womersley. Isometric, concentric, and eccentric torques for the knee flexors (KF) and extensors (KE) were measured using Biodex dynamometry. In the older male group, T-allele carriers of the C-1703T polymorphism in CNTFR performed significantly better on all noncorrected KF torques, whereas only noncorrected KE isometric torque at 120 degrees and concentric torque at 240 degrees/s were higher than the C/C homozygotes (P < 0.05). When age, height, and FFM were used as covariates, T-allele carriers performed only better on KE and KF isometric torque at 120 degrees (P < 0.05). Concentric KF torque at 180 degrees/s was lower in middle-aged female A-allele carriers compared with the T/T subjects for the T1069A polymorphism in CNTFR. After correction for age, height, and FFM, middle-aged female A-allele carriers exhibited lower values on all concentric KF strength measures and isometric torque at 120 degrees . There was a lack of association with the CNTF G-6A polymorphism in men, with inconclusive results for a limited number of phenotypes in women. No significant CNTF/CNTFR allele interaction effects were found. Results indicate that CNTFR C-1703T and T1069A polymorphisms are significantly associated with muscle strength in humans.     

Signification des caractères partagés entre Bennettitales et Cycadales. Implications de la découverte d''une Cycadale nouvelle du Cénomanien de l''Anjou (France)

The lagoonal Cenomanian formation (Lower Cretaceous) of clays of the region of Baugeois (north of Angers) has supplied an exceptionally well-preserved fossil flora: leaves, woody structures or/and reproductive organs of pteridophyta, gymnosperms and angiosperms. A well-preserved fossil plant found in a quarry “Le Brouillard” (8 km from Angers), has allowed a detailed morphological and structural study of this species. A comparative study with extant plants has confirmed an undoubted link between the contemporary genus Dioon (an endemic cycad from Mexico) and the fossil species. However, features observed on the lower epidermis of the leaflets, present a similarity with some Jurassic Bennettitales. This discovery, added to other common features shared by these two orders, raises questions about their relationships, thought to be different from a phylogenetic viewpoint.

Résumé

La formation lagunaire cénomanienne (Crétacé inférieur) des Argiles du Baugeois, au nord d'Angers, a fourni une flore fossile riche et exceptionnellement bien conservée: feuilles, structures ligneuses ou/et organes reproducteurs de ptéridophytes, de gymnospermes et d'angiospermes. L'excellent état de conservation d'un fragment de plante fossile, récolté dans la carrière Le Brouillard à 8 km d'Angers, a permis une étude détaillée de la morphologie et de la structure foliaire de cette plante. L'étude comparative avec des plantes actuelles a démontré l'existence d'un lien de parenté entre le genre Dioon (cycadale endémique du Mexique) et le fossile, mais des caractères originaux observés sur l'épiderme inférieur des folioles, présentent des similitudes avec certains genres de Bennettitales du Jurassique. Une telle découverte, ajoutée aux autres caractères communs préalablement décrits par d'autres auteurs, soulèvent à nouveau quelques questions sur les relations de parentés entre ces deux groupes supposés phylogénétiquement éloignés actuellement.     

The endothelin system in human and monkey ovaries: in situ gene expression of the different components

The endothelin system is composed of three endothelin isoforms (ET-1, ET-2, and ET-3), the endothelin receptors ETA and ETB, and the endothelin-converting enzyme (ECE). Besides having a major vasoactive role, endothelins have roles in different cell types at a local level. We investigated the presence of the different components of the endothelin system in primate ovaries. Human ovaries and gonadotropin-stimulated monkey ovaries were studied using immunohistochemistry for endothelin, and in situ hybridization with probes for ET-1, ET-2, ET-3, ETA and ETB receptors, and ECE. ET-1 and ETA receptors were detected in endothelial cells and vascular smooth muscle cells, respectively, in stromal vessels adjacent to follicles and corpora lutea. ETB receptors and ET-1 were found in the endothelial cells of capillaries of corpora lutea. ECE was present in internal theca cells of secondary, de Graaf, atretic follicles, and in luteinized granulosa cells of the corpora lutea. The endothelin system components are present in or around the follicles of human and monkey ovaries. Although the components are not expressed in the same cell types, they are synthesized, mainly in follicles, by cells that are in close proximity. Thus, the endothelin system could act in a paracrine manner. ECE expression in steroid-producing cells changes its compartmentalization during follicle maturation.     

A new Saccharomyces cerevisiae strain with a mutant Smt3-deconjugating Ulp1 protein is affected in DNA replication and requires Srs2 and homologous recombination for its viability

The Saccharomyces cerevisiae Srs2 protein is involved in DNA repair and recombination. In order to gain better insight into the roles of Srs2, we performed a screen to identify mutations that are synthetically lethal with an srs2 deletion. One of them is a mutated allele of the ULP1 gene that encodes a protease specifically cleaving Smt3-protein conjugates. This allele, ulp1-I615N, is responsible for an accumulation of Smt3-conjugated proteins. The mutant is unable to grow at 37 degrees C. At permissive temperatures, it still shows severe growth defects together with a strong hyperrecombination phenotype and is impaired in meiosis. Genetic interactions between ulp1 and mutations that affect different repair pathways indicated that the RAD51-dependent homologous recombination mechanism, but not excision resynthesis, translesion synthesis, or nonhomologous end-joining processes, is required for the viability of the mutant. Thus, both Srs2, believed to negatively control homologous recombination, and the process of recombination per se are essential for the viability of the ulp1 mutant. Upon replication, mutant cells accumulate single-stranded DNA interruptions. These structures are believed to generate different recombination intermediates. Some of them are fixed by recombination, and others require Srs2 to be reversed and fixed by an alternate pathway.