Workers' sons rescue genetic diversity at the sex locus in an invasive honey bee population

The hallmark of eusociality is the division of labour between reproductive (queen) and nonreproductive (worker) females. Yet in many eusocial insects, workers retain the ability to produce haploid male offspring from unfertilized eggs. The reproductive potential of workers has well‐documented consequences for the structure and function of insect colonies, but its implications at the population level are less often considered. We show that worker reproduction in honey bees can have an important role in maintaining genetic diversity at the sex locus in invasive populations. The honey bee sex locus is homozygous‐lethal, and, all else being equal, a higher allele number in the population lead to higher mean brood survival. In an invasive population of the honey bee Apis cerana in Australia, workers contribute significantly to male production: 38% of male‐producing colonies are queenless, and these contribute one‐third of all males at mating congregations. Using a model, we show that such male production by queenless workers will increase the number of sex alleles retained in nascent invasive populations following founder events, relative to a scenario in which only queens reproduce. We conclude that by rescuing sex locus diversity that would otherwise be lost, workers' sons help honey bee populations to minimize the negative effects of inbreeding after founder events and so contribute to their success as invaders.     

Two-component response regulators of Vibrio fischeri: identification, mutagenesis, and characterization

Two-component signal transduction systems are utilized by prokaryotic and eukaryotic cells to sense and respond to environmental stimuli, both to maintain homeostasis and to rapidly adapt to changing conditions. Studies have begun to emerge that utilize a large-scale mutagenesis approach to analyzing these systems in prokaryotic organisms. Due to the recent availability of its genome sequence, such a global approach is now possible for the marine bioluminescent bacterium Vibrio fischeri, which exists either in a free-living state or as a mutualistic symbiont within a host organism such as the Hawaiian squid species Euprymna scolopes. In this work, we identified 40 putative two-component response regulators encoded within the V. fischeri genome. Based on the type of effector domain present, we classified six as NarL type, 13 as OmpR type, and six as NtrC type; the remaining 15 lacked a predicted DNA-binding domain. We subsequently mutated 35 of these genes via a vector integration approach and analyzed the resulting mutants for roles in bioluminescence, motility, and competitive colonization of squid. Through these assays, we identified three novel regulators of V. fischeri luminescence and seven regulators that altered motility. Furthermore, we found 11 regulators with a previously undescribed effect on competitive colonization of the host squid. Interestingly, five of the newly characterized regulators each affected two or more of the phenotypes examined, strongly suggesting interconnectivity among systems. This work represents the first large-scale mutagenesis of a class of genes in V. fischeri using a genomic approach and emphasizes the importance of two-component signal transduction in bacterium-host interactions.     

RNA- and miRNA-interference to enhance abiotic stress tolerance in plants

Journal of Plant Biochemistry and Biotechnology - In response to rapidly changing environment, plants have employed a plethora of mechanisms that provide phenotypic plasticity and allow fine-tuning...     

Loss of Melanopsin Photoreception and Antagonism of the Histamine H3 Receptor by Ciproxifan Inhibit Light-Induced Sleep in Mice

Light has direct effects on sleep and wakefulness causing arousal in diurnal animals and sleep in nocturnal animals. In the present study, we assessed the modulation of light-induced sleep by melanopsin and the histaminergic system by exposing mice to millisecond light flashes and continuous light respectively. First, we show that the induction of sleep by millisecond light flashes is dose dependent as a function of light flash number. We found that exposure to 60 flashes of light occurring once every 60 seconds for 1-h (120-ms of total light over an hour) induced a similar amount of sleep as a continuous bright light pulse. Secondly, the induction of sleep by millisecond light flashes was attenuated in the absence of melanopsin when animals were presented with flashes occurring every 60 seconds over a 3-h period beginning at ZT13. Lastly, the acute administration of a histamine H3 autoreceptor antagonist, ciproxifan, blocked the induction of sleep by a 1-h continuous light pulse during the dark period. Ciproxifan caused a decrease in NREMS delta power and an increase in theta activity during both sleep and wake periods respectively. The data suggest that some form of temporal integration occurs in response to millisecond light flashes, and that this process requires melanopsin photoreception. Furthermore, the pharmacological data suggest that the increase of histaminergic neurotransmission is sufficient to attenuate the light-induced sleep response during the dark period.     

Timescale analyses of fluctuations in coexisting populations of a native and invasive tree squirrel

1. Competition from invasive species is an increasing threat to biodiversity. In Southern California, the western gray squirrel (Sciurus griseus, WGS) is facing competition from the fox squirrel (Sciurus niger, FS), an invasive congener.
2. We used spectral methods to analyze 140 consecutive monthly censuses of WGS and FS within a 11.3 ha section of the California Botanic Garden. Variation in the numbers for both species and their synchrony was distributed across long timescales (>15 months).
3. After filtering out annual changes, concurrent mean monthly temperatures from nearby Ontario Airport yielded a spectrum with a large semi‐annual peak and significant spectral power at long timescales (>28 months). The cospectrum between WGS numbers and temperature revealed a significant negative correlation at long timescales (>35 months). Cospectra also revealed significant negative correlations with temperature at a six‐month timescale for both WGS and FS.
4. Simulations from a model of two competing species indicate that the risk of extinction for the weaker competitor increases quickly as environmental noise shifts from short to long timescales.
5. We analyzed the timescales of fluctuations in detrended mean annual temperatures for the time period 1915–2014 from 1218 locations across the continental USA. In the last two decades, significant shifts from short to long timescales have occurred, from <3 years to 4–6 years.
6. Our results indicate that (i) population fluctuations in co‐occurring native and invasive tree squirrels are synchronous, occur over long timescales, and may be driven by fluctuations in environmental conditions; (ii) long timescale population fluctuations increase the risk of extinction in competing species, especially for the inferior competitor; and (iii) the timescales of interannual environmental fluctuations may be increasing from recent historical values. These results have broad implications for the impact of climate change on the maintenance of biodiversity.

     

Resonance Raman spectroscopy shows different temperature-dependent coordination equilibria for native horseradish and cytochrome c peroxidase

Resonance Raman spectra are reported for native horseradish peroxidase (HRP) and cytochrome c peroxidase (CCP) at 290, 77 and 9 K, using 406.7 nm excitation, in resonance with the Soret electronic transition. The spectra reveal temperature-dependent equilibria involving changes in coordination or spin state. At 290 K and pH 6.5, CCP contains a mixture of 5- and 6-coordinate high-spin Fe^III heme while at 9 K the equilibrium is shifted entirely to the 6-coordinate species. The spectra indicate weak binding of H₂O to the heme Pe, consistent with the long distance, 2.4 Å, seen in the crystal structure. At 290 K HRP also contains a mixture of high-spin Fe^III hemes with the 5-coordinate form predominant. At low temperature, a small 6-coordinate high-spin component remains but the 5-coordinate high-spin spectrum is replaced by another which is characteristic either of 6-coordinate low-spin or 5-coordinate intermediate spin heme. The latter species is definitely indicated by previous EPR studies at low temperature. This behavior implies that, in contrast to CCP, the distal coordination site of HRP is only partially occupied by H₂O at any temperature and that lowering the temperature significantly weakens the Fe-proximal imidazole bond. Consistent with this inference, the 77 K spectrum of reduced HRP shows an appreciable fraction of molecules having an Fe-imidazole stretching frequency of 222 cm⁻¹, a value indicating weakened H-bonding of the proximal imidazole.Resonance Roman spectroscopyHorseradish peroxidaseCytochrome c peroxidaseCoordination equilibrium     

Thrombocyte counting with the Laborscale (PSL-1/PSA-1) particle-counting instrument by Medicor (Budapest/Hungary) and thrombocyte volume analysis in the diagnosis of selected thrombocytopathies

A thrombocyte counting technique is presented in comparison with the chambre counting according to the German Book of Medicaments (DAB 7 D.L.) GDR on the particle counting device "Laborscale" (PSL-1/PSA-1) of Medicor by using a thrombofuge (70 g). The composition of reagents accounts for problems of measurement which are caused by the device and influences the separation of particles. The possibility of recording the curve of thrombocyte volume distribution and calculating the average thrombocyte volume (VM) is demonstrated by means of a normal collective of test persons as well as by intravascular disorders of haemostasis and during cytostatic therapy.     

HER-2/neu oncogene expression, DNA ploidy and proliferation index in breast cancer.

HER-2/neu gene expression, DNA ploidy and proliferation index were studied in 250 cases of breast cancer. Expression of HER-2/neu was determined by using an antibody to the HER-2/neu receptor. Ki-67 antibody was used to determine the proliferation index of the breast cancers, and the Feulgen method was used to assess DNA amounts in the tumor cells. Histochemical staining was quantitated by image analysis. Of the cancers studied, 72 were positive for overexpression of HER-2/neu protein; of these, 62 (86%) possessed near-tetraploid DNA content, and 47 (65%) had more than one G0G1 stem line (polyploid) of DNA distribution. Cells from the cases negative for HER/2-neu overexpression contained DNA amounts that ranged from diploid to varying degrees of aneuploid. A significant difference in the amounts of cellular proliferation in HER-2/neu overexpressing cancers was found between those that expressed the HER-2/neu receptor on their membranes and those that exhibited mainly cytoplasmic receptors.     

Analysis of Streptomyces avermitilis genes required for avermectin biosynthesis utilizing a novel integration vector.

An integration vector for gene analysis in Streptomyces has been constructed. This vector replicates in Escherichia coli, and integrates into Streptomyces by homologous recombination between a cloned fragment and the genome. To overcome methylation-specific restriction barriers, an E. coli mutant triply defective in DNA methylation was constructed as a source for the integration plasmids. The frequency of integration of pVE616 derivatives into the Streptomyces avermitilis genome was proportional to the size of the cloned DNA. Derivatives of pVE616, containing fragments from pVE650, a plasmid with a 24-kb insert of S. avermitilis DNA, were used in complementation analyses of seven S. avermitilis mutants defective in glycosylation of avermectin (Av). Three complementation groups, located in a 7-kb region, were identified. Derivatives of pVE616, containing fragments from the 18-kb of DNA adjacent to the glycosylation region, were integrated into an Av producer. Av produced from the integrants was substantially reduced, indicating that the 18 kb also encodes gene products which are involved in Av biosynthesis.