Evidence for ‘dawn’ and ‘dusk’ hourglasses in Pimpla photoperiodic clock

Abstract

Resonance experiments (Nanda‐Hamner protocol) conducted at two temperatures for diapause termination in Pimpla instigator (Hymenoptera: Ichneumonidae) do not support the view that the photoperiodic clock has an oscillatory component, but suggest the presence of a non‐rhythmic timer or hourglass mechanism. These results are best explained by a two hourglasses model, one of which starts at light‐on and measures the photophase and the other is initiated by light‐off and measures the scotophase. The most likely hypothesis is that the ratio of photophase to scotophase lengths is the determining element. Good agreement is obtained between results predicted by two hourglasses model and results observed in Pimpla. The diurnal hourglass continues to run for long time (several months) in constant condition (LL) and does not require to be ‘turned over’ by D/L transition, in contrary to the classical model of hourglass which executes a single act of time measurement in extented phase and then stops. The most simple explanation is that some essential factor of diapause termination is synthesized during photophase and degraded during scotophase. Therefore an independent photoperiodic counter (for sommation of daily informations) is not necessary. The two hourglasses system serves as photoperiodic clock and accumulation of product as counter.     

Assembling a clock for all seasons: are there M and E oscillators in the genes?

The hypothesis is advanced that the circadian pacemaker in the mammalian suprachiasmatic nucleus (SCN) is composed at the molecular level of a nonredundant double complex of circadian genes (per1, cry1, and per2, cry2). Each one of these sets would be sufficient for the maintenance of endogenous rhythmicity and thus constitute an oscillator. Each would have slightly different temporal dynamics and light responses. The per1/cry1 oscillator is accelerated by light and decelerated by darkness and thereby tracks dawn when day length changes. The per2 /cry2 oscillator is decelerated by light and accelerated by darkness and thereby tracks dusk. These M (morning) and E (evening) oscillators would give rise to the SCN's neuronal activity in an M and an E component. Suppression of behavioral activity by SCN activity in nocturnal mammals would give rise to adaptive tuning of the endogenous behavioral program to day length. The proposition-which is a specification of Pittendrigh and Daan's E-M oscillator model-yields specific nonintuitive predictions amenable to experimental testing in animals with mutations of circadian genes.     

Evidence for the presence of volume-sensitive KCl transport in ‘young’ human red cells

‘Young’ human red cells are shown to possess a specific K⁺ pathway which is dependent on Cl⁻ and sensitive to cell volume. This system was latent in ‘mature’ cells but was revealed by high hydrostatic pressure. This suggests the pathway is functionally active in ‘young’ cells but becomes masked with cell maturation.     

Rethinking the ‘everyday’ in ‘ethnicity and everyday life’

While ‘ethnicity and everyday life’ is a familiar collocation, sociologists concerned with racism and ethnicity have not engaged very much with the extensive body of social theory that takes the ‘everyday’ as its central problematic. In this essay, I consider some of the ways in which the sociology of the everyday might be of use to those concerned with investigating ethnicity and racism. For its part, however, the sociology of the everyday has tended to be remarkably blind to the role played by racism and racialization in the modern world. It is thus no less crucial to consider how the experiences of racialized groups might help us rethink influential accounts of the everyday. To this end, I provide a discussion of pioneering texts by C. L. R. James and W. E. B. du Bois, both of whom were driven by their reflections on racism and resistance to recognize the everyday not as an unremarked context, but as, precisely, a problematic one.     

Comparison of ‘ignition’ and ‘extraction’ methods for the determination of organic phosphate in rocks and soils

Summary Ignition markedly increased the solubility in dilute acid of iron- and aluminium-bound inorganic phosphate in samples of weathered New Zealand greywacke rock. This observation supports the view that ignition methods may sometimes overestimate the total organic phosphate of soils.     

‘Twisted plywood’ structure and mineralization in the scales of a primitive living fish Amia calva

The basal plate of the scales of Amia calva is composed of regular double twisted plywood, as in Latimeria and Dipnoan scales. However, the progressive rotation of the fibrils direction is left-handed in Amia and right-handed in the ‘Sarcopterygians’. So, the similarity between these peculiar plywoods is probably the result of convergence. The basal plate of Amia scales is incompletely mineralized. There are numerous calcified ovoid corpuscles which look very like the Mandl's corpuscles of Teleost scales. The mineralization probably progresses essentially by the fusion of these corpuscles, as in Teleost scales, and would be inotropic rather than spheritic.     

Experimental analysis of the ‘Paarkultureffekt’ in the protandric polychaete, Ophryotrocha puerilis Clap. Mecz.

Female Ophyrotrocha puerilis Clap. Mecz. were coupled. Certain parts of the prostomium and of the pygidium in one or both partners of a couple were amputated in order to prove that they are responsible for the mutual influence which partners normally exert on their sexual differentiation. The results demonstrate that the palps and the ventrolateral prostomial cirri are the transmitters and the ciliated lateral pits on the prostomium the receivers of the mutual influence. The antennae and the pygidial cirri are not necessary as far as the ‘Paarkultureffekt’ is concerned. The nature of the stimulus is still unknown. At the present stage of these investigations, the favoured conception is of a pheromone transmitted during the contact of the partners.     

Oddity and the ‘confusion effect’ in predation

We report on two sets of experiments designed to clarify the roles of sensory ‘confusion’ and prey ‘oddity’ as they interact to influence the hunting success of a pursuit predator, the largemouth bass (Micropterus salmoides), on silvery minnows (Hybognathus nuchalis). Bass quickly captured solitary minnows, but performed many unsuccessful attacks and took much longer to make a capture as prey school size was increased. At school sizes of eight and above, bass were effectively stymied, demonstrating the ‘confusion effect’. The inclusion of one or two ‘odd’ (blue-dyed) minnows in a school of eight greatly increased the ability of bass to capture both normal and odd prey, but this effect of oddity disappeared at a school size of 15. The implications of these results for understanding the adaptive basis of mixed species flocks, herds and schools is discussed.     

Determination of the CCR5∆32 frequency in Emiratis and Tunisians and the screening of the CCR5 gene for novel alleles in Emiratis

Background

The chemokine receptor components play crucial roles in the immune system and some of them serve as co-receptors for the HIV virus. Several studies have documented that variants in chemokine receptors are correlated with susceptibility and resistance to infection with HIV virus. For example, mutations in the chemokine receptor 5 gene (CCR5) resulting in loss-of-function (such as the homozygous CCR5?32) confer high degree of resistance to HIV infection. Heterozygotes for these variants exhibit slow progression to AIDS. The prevalence of CCR5 polymorphisms varies among ethnic and geographical groups. For example, the CCR5?32 variant is present in 10–15% of north Europeans but is rarely encountered among Africans. This study aims to identify the prevalence of some CCR5 variants in two geographically distant Arab populations (namely Emiratis and Tunisians).

Methodology

The prevalence of CCR5 gene variants including CCR5?32, FS299, C101X, A29S and C178R has been determined using PCR and direct DNA sequencing. A total of 403 unrelated healthy individuals (253 Emiratis and 150 Tunisians) were genotyped for the CCR5?32 variant using PCR amplification and gel electrophoresis. In addition, 200 Emiratis have been screened for other SNPs using Sanger DNA sequencing.

Results

Among Emiratis, the allele frequency of the CCR5?32 variant has been found to be 0.002. In addition, two variants L55Q and A159 were found at a frequency of 0.002. Moreover, the prevalence of the CCR5?32 variant in Tunisians was estimated to be 0.013 which is relatively higher than its frequency in Emiratis but lower than Europeans.

Conclusion

We conclude that the allele frequency of the most critical CCR5 polymorphism (?32) is extremely low among Emiratis compared to other Arabs and North Europeans. In addition, very low allele frequencies of other CCR5 polymorphisms have been detected among Emiratis.     

Female macaques compete for ‘power’ and ‘commitment’ in their male partners

The formation of male-female social bonds and the resulting competition among females for male partners is a core element of human societies. While female competition for a male partner outside the mating context is well studied in humans, evidence from non-human primates is scarce, and its evolutionary roots remain to be explored. We studied two multi male – multi female groups of wild Assamese macaques (Macaca assamensis), a species where females gain benefits from selectively affiliating with particular males. Using a behavioral data set collected over several years, we tested whether females competed over access to male social partners, whether success in competition was driven by female dominance rank, and which male traits were most attractive for females. We found assortative bonding by dominance rank between females and males, which together with females initiating and maintaining contact suggests direct female competition over males. Two male traits independently predicted male attractiveness to females: (1) current dominance rank, a measure of 'power' or a male's ability to provide access to resources, and (2) prior male affiliation with immatures, a measure of a male's potential paternal proclivity or 'commitment' to infant care. Both traits have been consistently identified as drivers of female partner choice in humans. Our study adds to the evidence that female competition for valuable male partners is not unique to humans, suggesting deep evolutionary origins of women's mate choice tendencies for ‘power’ and ‘commitment’.     

Mutations and addiction to EGFR: the Achilles ‘heal’ of lung cancers?

The epidermal growth factor receptor (EGFR) gene product is a receptor tyrosine kinase (TK) that affects many important downstream pathways. The recent finding that mutations in EGFR predict the response of lung cancers to therapies that target the TK domain of the gene product has generated considerable interest. The mutations are associated with adenocarcinoma histology, oriental origin, female gender and never-smoker status. Most mutations target structures in the TK domain that appear to be essential for the phosphorylation function of the gene. Cancer cells with mutant EGFR genes might become physiologically dependent on the continued activity of the gene for the maintenance of their malignant phenotype; however, this might also be a target for therapy.     

Evidence for Mate Guarding Behavior in the Taylor’s Checkerspot Butterfly

Discerning the intricacies of mating systems in butterflies can be difficult, particularly when multiple mating strategies are employed and are cryptic and not exclusive. We observed the behavior and habitat use of 113 male Taylor’s checkerspot butterflies (Euphydryas editha taylori). We confirmed that two distinct mating strategies were exhibited; patrolling and perching. These strategies varied temporally in relation to the protandrous mating system employed. Among perching males, we recorded high site fidelity and aggressive defense of small (<5 m²) territories. This territoriality was not clearly a function of classic or non-classic resource defense (i.e., host plants or landscape), but rather appeared to constitute guarding of female pupae (virgin females). This discrete behavior is previously undocumented for this species and has rarely been observed in butterflies.     

Evidence for a ‘silent allele’ GLO 0 at the glyoxalase I locus

Summary In a three-generation family, the segregation of an apparent silent allele at the GLO I locus in association with the rare HLA haplotype AW30-CW4-BW35 was observed in four members. In two cases the assumption of homozygosity at the GLO locus would lead to mother-child exclusions. Phenotypically, the GLO activity in the GLO ⁰ carriers is clearly diminished.With rechnical assistance of Mrs. C. Walter and Mrs. M. MuellerSupported by the Deutsche Forschungsgemeinschaft (Ri 164/12)     

Differential responses of the photoperiodic clock in two passerine birds possessing a strongly self‐sustained circadian system

To investigate whether the photoperiodic clocks of species possessing strongly self‐sustaining circadian clocks share identical features, we compared the full response cycle (initiation and termination of the response) in body mass and testes of the non‐migratory house sparrow (Passer domesticus) with that of the migratory redheaded bunting (Emberiza bruniceps) under Nanda‐Hamner experiments. Birds were exposed to a 36 h day (L∶D=6∶30 h), controls exposed to a 24 h day (L∶D=6∶18 h), for a period of 31 weeks. By week 18 of L∶D=6∶18 h, there was a small increase in body mass among sparrows, but not among buntings, and the testes of bunting did not grow, while those of sparrow grew slightly. The response to L∶D=6∶30 h is of particular interest. There was a rapid gain and subsequent loss in the body mass of bunting, but not of sparrows. Further, both species underwent a testicular cycle as if they were exposed to long days, but the response of sparrows was slower and hence delayed the attainment of peak testicular size. Such a differential response to exotic light cycles between these two photosensitive species, despite their similar circadian oscillatory properties (strong self‐sustainment), could suggest a species‐specific adaptation of the endogenous clock involved in photoperiodic regulation of avian seasonality.