Direct and indirect effects of sexual signal loss on female reproduction in the Pacific field cricket (Teleogryllus oceanicus)

Sexual signal evolution may present fitness consequences for the non‐signaling sex due to shared genes and altered social conditions, but this is rarely studied in natural populations. On the Hawaiian Island of Kauai, most male Teleogryllus oceanicus (Pacific field crickets) lack the ability to sing because of a novel wing mutation (flatwing) that arose and spread in <20 generations. Obligately silent flatwing males have been highly successful because they avoid detection by a deadly, acoustically‐orienting parasitoid fly. Little is known about how the flatwing mutation and resulting song‐less acoustic environment affects female fitness. We found that Kauai females carrying the flatwing allele invested less in reproductive tissues and experienced more instances of mating failure than normal‐wing‐carrying females, though total offspring production did not differ between female genotypes. Females from Oahu (HI, where the parasitoid and flatwing also occur) and Mangaia (an island in the Cook Islands which harbors neither the parasitoid nor flatwing) invested less in reproductive tissues when reared in a song‐less acoustic environment. Kauai females did not exhibit this plasticity, perhaps because they have experienced nearly song‐less conditions for the past ~15 years following the establishment of flatwing. We show that female T. oceanicus experience a mix of costly and beneficial effects of sexual signal loss, which should help maintain the wing polymorphism in the wild. Our results demonstrate that the non‐signaling sex can experience a nuanced set of phenotypic consequences resulting from signal evolution, which can further shape dynamics of sexual signal evolution.     

Sequencing of 15 622 gene‐bearing BACs clarifies the gene‐dense regions of the barley genome

Barley (Hordeum vulgare L.) possesses a large and highly repetitive genome of 5.1 Gb that has hindered the development of a complete sequence. In 2012, the International Barley Sequencing Consortium released a resource integrating whole‐genome shotgun sequences with a physical and genetic framework. However, because only 6278 bacterial artificial chromosome (BACs) in the physical map were sequenced, fine structure was limited. To gain access to the gene‐containing portion of the barley genome at high resolution, we identified and sequenced 15 622 BACs representing the minimal tiling path of 72 052 physical‐mapped gene‐bearing BACs. This generated ~1.7 Gb of genomic sequence containing an estimated 2/3 of all Morex barley genes. Exploration of these sequenced BACs revealed that although distal ends of chromosomes contain most of the gene‐enriched BACs and are characterized by high recombination rates, there are also gene‐dense regions with suppressed recombination. We made use of published map‐anchored sequence data from Aegilops tauschii to develop a synteny viewer between barley and the ancestor of the wheat D‐genome. Except for some notable inversions, there is a high level of collinearity between the two species. The software HarvEST:Barley provides facile access to BAC sequences and their annotations, along with the barley–Ae. tauschii synteny viewer. These BAC sequences constitute a resource to improve the efficiency of marker development, map‐based cloning, and comparative genomics in barley and related crops. Additional knowledge about regions of the barley genome that are gene‐dense but low recombination is particularly relevant.     

Relationship between cellular electrolytes and the contraction force of isolated guinea-pig atria with special regard to the extracellular space volume

A micromethod is described which allows the quantitative evaluation of the extracellular space volume of isolated guinea-pig atria (> 15 mg tissue wet weight) by means of an enzymatic estimation of inulin. In addition, the acidic tissue extracts are analysed for the potassium, sodium, magnesium, calcium and ⁴⁵calcium content. Taking into account the individual extracellular space volumes, it is possible to calculate the cellular electrolyte content and relative specific ⁴⁵calcium activity of each atrium. Our experiments reveal under steady state conditions a significant correlation between the force of contraction and the cellular electrolyte content. Atria with a higher contraction force were found to contain a significantly elevated cellular potassium content and a lower content of cellular sodium and calcium than atria with a smaller contraction force. The decrease of cellular calcium content is exclusively caused by the lowering of the fraction of unexchanged tissue calcium. The significance of the results is discussed with respect to the events leading to contraction and relaxation of the heart muscle.     

Siliciumstoffwechsel bei Mikroorganismen

Summary Soil bacteria which have been used in earlier experiments to demonstrate an active uptake of silicon, loose phosphate during silicon uptake when cultured in P-free medium. This could be shown by comparable determinations of the phosphate and silicon concentration of the cells. Under the conditions given in our experiments the exchange of Si for P lies in the range of 1:2. By addition of rising P-concentrations to media with constant concentration of Si, it was shown that about 100 P/ml will completely inhibit the uptake of silicon within 24 hours. Increasing concentrations of phosphate going along with decreasing concentrations of silicate showed to cause a linear decrease of Si-uptake intensity within the first 24 hours in the range of 20–100 P/ml. Above these concentrations (and the proportion of Si/P=1:4) silicon uptake is completely inhibited independent of phosphate concentrations. About 10% of the silicon incorporated can be extracted from the cells with ethanol in the form of instable, easily hydrolysable complexes. The entire silicon of the cells is completely exchanged against phosphate when silicon containing cells are cultured in Si-free phosphate medium, whereas cells adapted to silicon will not extrude the silicon taken up before, when incubated in a medium containing both elements. References to the possible synthesis of organic silicon compounds resulting from these experiments are discussed.     

Dietary inorganic nitrate mobilizes circulating angiogenic cells

Nitric oxide (NO) was implicated in the regulation of mobilization and function of circulating angiogenic cells (CACs). The supposedly inert anion nitrate, abundant in vegetables, can be stepwise reduced in vivo to form nitrite, and consecutively NO, representing an alternative to endogenous NO formation by NO synthases. This study investigated whether inorganic dietary nitrate influences mobilization of CACs. In a randomized double-blind fashion, healthy volunteers ingested 150 ml water with 0.15 mmol/kg (12.7 mg/kg) of sodium nitrate, an amount corresponding to 100-300 g of a nitrate-rich vegetable, or water alone as control. Mobilization of CACs was determined by the number of CD34(+)/KDR(+) and CD133(+)/KDR(+) cells using flow cytometry and the mobilization markers stem cell factor (SCF) and stromal cell-derived factor-1a (SDF-1α) were determined in plasma via ELISA. Nitrite and nitrate were measured using high-performance liquid chromatography and reductive gas-phase chemiluminescence, respectively. NOS-dependent vasodilation was measured as flow-mediated vasodilation. Further mechanistic studies were performed in mice after intravenous application of nitrite together with an NO scavenger to identify the role of nitrite and NO in CAC mobilization. Nitrate ingestion led to a rise in plasma nitrite together with an acute increase in CD34(+)/KDR(+) and CD133(+)/KDR(+)-CACs along with increased NOS-dependent vasodilation. This was paralleled by an increase in SCF and SDF-1α and the maximal increase in plasma nitrite correlated with CD133(+)/KDR(+)-CACs (r=0.73, P=0.016). In mice, nitrate given per gavage and direct intravenous injection of nitrite led to CAC mobilization, which was abolished by the NO scavenger cPTIO, suggesting that nitrite mediated its effect via formation of NO. Dietary inorganic nitrate acutely mobilizes CACs via serial reduction to nitrite and NO. The nitrate-nitrite-NO pathway could offer a novel nutritional approach for regulation of vascular regenerative processes.     

Biomechanics of bone-fracture fixation by stiffness-graded plates in comparison with stainless-steel plates

Background  

In the internal fixation of fractured bone by means of bone-plates fastened to the bone on its tensile surface, an on-going concern has been the excessive stress-shielding of the bone by the excessively-stiff stainless-steel plate. The compressive stress-shielding at the fracture-interface immediately after fracture-fixation delays callus formation and bone healing. Likewise, the tensile stress-shielding of the layer of the bone underneath the plate can cause osteoporosis and decrease in tensile strength of this layer.