Male-limited evolution suggests no extant intralocus sexual conflict over the sexually dimorphic cuticular hydrocarbons of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Sexually dimorphic traits are likely to have evolved through sexually antagonistic selection. However, recent empirical data suggest that intralocus sexual conflict often persists, even when traits have diverged between males and females. This implies that evolved dimorphism is often incomplete in resolving intralocus conflict, providing a mechanism for the maintenance of genetic variance in fitness-related traits. We used experimental evolution in Drosophila melanogaster to directly test for ongoing conflict over a suite of sexually dimorphic cuticular hydrocarbons (CHCs) that are likely targets of sex-specific selection. Using a set of experimental populations in which the transmission of genetic material had been restricted to males for 82 generations, we show that CHCs did not evolve, providing experimental evidence for the absence of current intralocus sexual conflict over these traits. The absence of ongoing conflict could indicate that CHCs have never been the target of sexually antagonistic selection, although this would require the existing dimorphism to have evolved via completely sexlinked mutations or as a result of former, but now absent, pleiotropic effects of the underlying loci on another trait under sexually antagonistic selection. An alternative interpretation, and which we believe to be more likely, is that the extensive CHC sexual dimorphism is the result of past intralocus sexual conflict that has been fully resolved, implying that these traits have evolved genetic independence between the sexes and that genetic variation in them is therefore maintained by alternative mechanisms. This latter interpretation is consistent with the known roles of CHCs in sexual communication in this species and with previous studies suggesting the genetic independence of CHCs between males and females. Nevertheless, direct estimates of sexually antagonistic selection will be important to fully resolve these alternatives.     

The Onychophora of Trinidad, Tobago and the Lesser Antilles

This paper brings together the scattered literature on the Onychophora from Trinidad, Tobago and the Lesser Antilles. The 11 known species from this area are described, incorporating new material collected by the author. Scanning electron micrographs of the dorsal integument are presented for all but one species. Parthenogenesis is reported in a population of Epiperipatus imthurni from Trinidad.     

Proceedings of the signature series symposium “cellular therapies for orthopaedics and musculoskeletal disease proven and unproven therapies—promise,facts and fantasy,” international society for cellular therapies,montreal, canada,may 2, 2018

The Signature Series Symposium “Cellular Therapies for Orthopaedics and Musculoskeletal Disease Proven and Unproven Therapies—Promise, Facts and Fantasy” was held as a pre-meeting of the 26^th International Society for Cellular Therapy (ISCT) annual congress in Montreal, Canada, May 2, 2018. This was the first ISCT program that was entirely dedicated to the advancement of cell-based therapies for musculoskeletal diseases. Cellular therapies in musculoskeletal medicine are a source of great promise and opportunity. They are also the source of public controversy, confusion and misinformation. Patients, clinicians, scientists, industry and government share a commitment to clear communication and responsible development of the field. Therefore, this symposium convened thought leaders from around the world in a forum designed to catalyze communication and collaboration to bring the greatest possible innovation and value to patients with musculoskeletal conditions.     

Transcript profiling and gene expression analysis under drought stress in <Emphasis Type="Italic">Ziziphus nummularia</Emphasis> (Burm.f.) Wright &amp; Arn.

Drought is one of the prime abiotic stresses responsible for limiting agricultural productivity. A number of drought responsive genes have been isolated and functionally characterized but these studies have been restricted to a few model plant systems. Very few drought responsive genes have been reported till date from non model drought tolerant plants. The present study aimed at identifying differentially expressed genes from a drought tolerant, non-model plant, Ziziphus nummularia (Burm.f.) Wight & Arn. One month old seedlings of Z. nummularia were subjected to drought stress by 30% Polyethylene glycol (PEG 6000) treatment for 6, 12, 24, 48 and 72 h. A significant reduction in RWC and increase in proline was observed at 24 h and 48 h of treatment. Suppression subtractive hybridization (SSH) library was constructed with drought stressed seedlings after 24 h and 48 h of PEG 6000 treatment. A total of 142 and 530 unigenes from 24 h and 48 h library were identified respectively. Gene ontology studies revealed that about 9.78% and 15.07% unigenes from 24 h and 48 h SSH libraries were expressed in “response to stress”. Fifteen putative drought responsive genes identified in SSH library were validated for drought responsive differential expression by RT-qPCR. Significant changes in fold expressions were observed with time in the treated samples compared to the control. A heat map revealing the expression profile of genes was constructed by hierarchical clustering. Various genes identified in SSH libraries can serve as a resource for marker discovery and selection of candidate genes to improve drought tolerance in other susceptible crops.     

Specific foetal growth rates of cetaceans

The numerous data in the International Whaling Statistics relating foetal length to date of catch have been studied. They can be used as alternatives to cube roots of foetal weights to give rates of foetal growth and for the computation of data of conception and foetal ages. There are major differences between the Mysticeti and Odontoceti. The main gestation period for the former is 10.8.±1-2 months and for the latter 14 ± 2 months. In both groups the greatest birth-weight is attained by an increased foetal growth rate, to such an extent in the rorquals that the gestation period in the largest is actually shorter than in the smaller species. There are dietetic and metabolic differences between the two sub-cohorts. The outstanding one is that pregnant mysticetes appear to stop feeding and lose body fat to the foetus during late pregnancy, at the time when the foetal increase in size is maximal. The causes of the differences in growth and metabolism of the two groups are unknown, apart from those imposed by differences in their ecology.