HALDANE'S RULE IS EXTENDED TO PLANTS WITH SEX CHROMOSOMES

Haldane's rule is an empirical phenomenon that has been observed in animals with sex chromosomes. The rule states that the heterogametic sex (XY or ZW) will be “absent, rare, or sterile” following hybridization between two species. Despite the near ubiquity of Haldane's rule in animal hybridizations, it has not been documented in organisms other than animals. Here, we show evidence for both rarity and sterility in hybrid male but not female offspring in crosses between three dioecious plant species from the genus Silene with heteromorphic (XY) sex chromosomes. Our results are consistent with Haldane's rule, extending its applicability to plants with sex chromosomes.     

Efficacy of self monitoring of blood glucose in patients with newly diagnosed type 2 diabetes (ESMON study): randomised controlled trial

Objectives To assess the effect of self monitoring of blood glucose concentrations on glycaemic control and psychological indices in patients with newly diagnosed type 2 diabetes mellitus.Design Prospective randomised controlled trial of self monitoring versus no monitoring (control).Setting Hospital diabetes clinics.Participants 184 (111 men) people aged <70 with newly diagnosed type 2 diabetes referred to the participating diabetes clinics. Major exclusion criteria were secondary diabetes, insulin treatment, previous self monitoring of blood glucose.Interventions Participants were randomised to self monitoring or no monitoring (control) groups for one year with follow-up at three monthly intervals. Both groups underwent an identical structured core education programme. The self monitoring group received additional education on monitoring.Main outcome measures Between group differences in HbA_1c, psychological indices, use of oral hypoglycaemic drugs, body mass index (BMI), and reported hypoglycaemia rates.Results 96 patients (55 men) were randomised to monitoring and 88 (56 men) to control. There were no baseline differences in mean (SD) age (57.7 (11.0) in monitoring group v 60.9 (11.5) in control group) or HbA_1c (8.8 (2.1)% v 8.6 (2.3)%, respectively). Those in the monitoring group had a higher baseline BMI (34 (7) v 32 (6.2)). There were no significant differences between groups at any time point (12 months values given) in HbA_1c (6.9 (0.8)% v 6.9 (1.2)%, P=0.69; 95% confidence interval for difference −0.25% to 0.38%), BMI (33.1 (6.4) v 31.8 (6.0); adjusted for baseline BMI, P=0.32), use of oral hypoglycaemic drugs, or reported incidence of hypoglycaemia. Monitoring was associated with a 6% higher score on the depression subscale of the well-being questionnaire (P=0.01).Conclusions In patients with newly diagnosed type 2 diabetes self monitoring of blood glucose concentration has no effect on glycaemic control but is associated with higher scores on a depression subscale.Trial registration ISRCTN 49814766.     

Is body size a good indicator of fecundity in the genus Thaumetopoea? A story told by two intrageneric Mediterranean forest defoliators

1. Body size correlates with several factors such as reproductive fitness, environmental changes, the quality and quantity of food during critical development stages, and the feeding season. For the Palearctic moths of the genus Thaumetopoea (Lepidoptera; Notodontidae), the larval development is crucial and differs between species according to their feeding season; larvae of the pine processionary moth Thaumetopoea pityocampa (Denis & Schiffermüller 1775) feed during winter while larvae of its congeneric cedar processionary moth Thaumetopoea bonjeani (Powell 1922) develop during summer in North Africa.
2. This discrepancy in lifecycles leads to different reproductive traits such as egg batch length, number of eggs per batch, eggs protection mechanisms and female body size.
3. According to Darwin's fecundity advantage hypothesis (1871), female body size should have a positive influence on reproductive fitness, since larger females supposedly have higher fecundity. The universal allometric scaling phenomenon rule proposed by Rensch (1950) predicts that the degree of sexual size dimorphism tends to decrease with the increase of female body size.
4. Here, two morphometrical parameters that is, body size and scale size, estimated from body measurements of individuals of both species, feeding on the same host Atlantic cedar Cedrus atlantica (Manetti & Carrière 1855) (Pinales; Pinaceae) in Algeria were proposed. The aim was to find out traits that might rule the competition for food and space, in particularly fecundity and body size.
5. Results of the present study highlight a female-biased sexual size dimorphism in both species. The positive correlation between female body size and fecundity shown in this study weakly supports Darwin's hypothesis. Finally, the intrageneric test performed leads to conclude that Rensch's rule does not hold in the considered species.

     

Deletion of Mbtps1 (Pcsk8, S1p,Ski-1) Gene in Osteocytes Stimulates Soleus Muscle Regeneration and Increased Size and Contractile Force with Age

Conditional deletion of Mbtps1 (cKO) protease in bone osteocytes leads to an age-related increase in mass (12%) and in contractile force (30%) in adult slow twitch soleus muscles (SOL) with no effect on fast twitch extensor digitorum longus muscles. Surprisingly, bone from 10–12-month-old cKO animals was indistinguishable from controls in size, density, and morphology except for a 25% increase in stiffness. cKO SOL exhibited increased expression of Pax7, Myog, Myod1, Notch, and Myh3 and 6-fold more centralized nuclei, characteristics of postnatal regenerating muscle, but only in type I myosin heavy chain-expressing cells. Increased expression of gene pathways mediating EGF receptor signaling, circadian exercise, striated muscle contraction, and lipid and carbohydrate oxidative metabolism were also observed in cKO SOL. This muscle phenotype was not observed in 3-month-old mice. Although Mbtps1 mRNA and protein expression was reduced in cKO bone osteocytes, no differences in Mbtps1 or cre recombinase expression were observed in cKO SOL, explaining this age-related phenotype. Understanding bone-muscle cross-talk may provide a fresh and novel approach to prevention and treatment of age-related muscle loss.     

Handstand Scent Marking in the Dwarf Mongoose (Helogale parvula)

Many mammal species adopt marking postures that elevate their scent deposits. The most extreme of these is handstand marking, in which an individual reverses against an upright object, flings its hind legs into the air above its back and balances bipedally on its fore feet. The resulting anogenital deposit is thus raised one full body length above ground level. It has been suggested that this energetically costly form of marking serves to provide conspecifics with information about the marker's body size and hence competitive ability. However, this explanation assumes that the height of an individuals’ deposit does reflect accurately its body size, an assumption that has never been tested in any hand‐standing species. This study investigated the relationship between body size and handstand mark height in a wild population of dwarf mongooses (Helogale parvula) in South Africa. We found that although body size and marking height were correlated positively for female dwarf mongooses, they were not related for males. Male dwarf mongooses (who are subject to intrasexual competition from outside their group) invested more heavily in anogenital range marking, marking at three times the female frequency and placing their deposits significantly higher than females (although they were not dimorphic). Males that were particularly vulnerable to rivals (i.e. those that were small for their age) tended to mark higher than more robust age‐mates, in keeping with the predictions of Adams & Mesterton‐Gibbons’ (1995, J. Theor. Biol.175, 405–421). model of deceptive threat communication. These findings suggest strongly that the height of anogenital scent deposits is of social significance to dwarf mongooses.     

Merged mechanisms for hydride transfer from 1,4-dihydronicotinamides

Recent work on the reduction of heteroaromatic cations by 1,4-dihydronicotinamides and related reducing agents is reviewed. Extensive correlations are presented between the second-order rate constants (k₂) for these reactions and the second-order rate constants (k_OH) and equilibrium constants (pK_R⁺) for hydroxide ion attack on these cations. Close correlations of log k₂ with the electron affinities and one-electron reduction potentials of these cations are also presented. These relationships are considered in the context of a direct hydride transfer from donor to acceptor and also in terms of SET mechanisms which are also commonly discussed for such reactions. It is shown that the interpretation of these formal hydride transfer reactions in terms of an imbalanced development of electronic charge and C---H bond fission within the transition state species leads to a rational merging of the single-step hydride transfer mechanism and the SET mechanisms. The structures of the transition state species are expected to be highly variable and quite dependent upon the nature of the hydride donor and acceptor species, with considerable contribution from charge-transfer interactions. Such imbalanced transition state species are analyzed in terms of two different types of reaction coordinate diagrams and also in terms of the valence bond configuration mixing theory.     

Genetic variation in supernatant malate dehydrogenase of birds and reptiles

Electrophoretic variants of supernatant malate dehydrogenase were found within populations of a brid (Pitohui kirhocephalus) and of a reptile (Chrysemys picta). Upon starch gel electrophoresis, tissue extracts from variant individuals exhibit three equally spaced bands of supernatant malate dehydrogenase activity, whose staining intensities are approximately in a ratio of 1:2:1. Normal individuals, on the other hand, exhibit a single major band which is identical in mobility with the fastest of the variant bands. Immunological tests show that the Pitohui and Chrysemys enzymes are homologous with the well-characterized supernatant malate dehydrogenase of the domestic chicken. These results along with those obtained on other species imply that birds, reptiles, mammals, and certain invertebrates may possess a single locus coding for supernatant malate dehydrogenase. By contrast, some species of fishes and invertebrates possess multiple loci for this enzyme. A notable feature of the present investigation was the use of phenoxyethanol for extracting malate dehydrogenases from bird tissues. Extracts were prepared simply by soaking tissue in an aqueous solution of this reagent, no homogenization or centrifugation being required.This investigation was supported by funds from a research grant awarded by the National Science Foundation (GB-13119) and a U.S. Public Health Service Training Grant (GM 31-12).     

Influx and efflux kinetics of cationic dye binding to respiring mitochondria.

We have investigated the kinetics of interaction of cationic fluorescent lipophiles (dyes) rhodamine 123, rhodamine 6G, tetramethyl rhodamine ethyl ester, safranine O, 1,1'-diethyloxacarbocyanine, 1,1'-diethyloxadicarbocyanine, and 1,1'-diethylthiadicarbocyanine iodide with isolated respiring rat-liver mitochondria (RLM). Dye flux across the RLM inner membrane was measured by following the kinetics of fluorescence signal change after mixing of dye and RLM. The time course of fluorescence was analysed in terms of a kinetic model of the binding and transport processes involved. The rate constants of dye influx and efflux were extracted from the observed effect on the apparent time constant of fluorescence change to equilibrium intensity upon mixing dye with increasing concentrations of RLM. From the influx rate constants obtained, the apparent permeability constants for dye influx (at zero potential) across the membrane were calculated and ranged from 3 to 140 x 10(-4) cm/s. The influx rate constant was found to be linearly related to relative dye lipophilicity, as predicted by the model. As another test of the model, from the ratio of the influx and efflux rate constants, the apparent trans-membrane potential, psi, was calculated and found generally to agree with reported values, but to depend on the lipophilicity of the dye used. Not predicted by the simple model was a dissymmtry observed in the influx and efflux time constants for fluorescence change to equilibrium intensity. Inferences are made relating to the utility of these dyes as probes of psi.