Reproduction and recruitment in perennial colonies of the introduced wasp Vespula germanica

We investigated the genetic structure of perennial colonies of the yellowjacket wasp (Vespula germanica) in its introduced range in Australia and New Zealand. The nuclear genotypes of 712 gynes from 21 colonies, 147 workers from 5 colonies, and 81 males from 4 colonies were assayed at three polymorphic microsatellite loci. The mitochondrial haplotypes of all wasps also were determined for a 450-bp region of the mtDNA using double-stranded conformational polymorphism (DSCP) analysis. We found that multiple reproductives were needed to explain the genotypes of gynes, workers, and males in 7 of 21, 2 of 5, and 2 of 4 colonies, respectively, and that nestmate relatedness of these three castes equaled 0.42, 0.16, and 0.22, respectively. The mitochondrial data revealed that all individuals shared the same mtDNA haplotype in 20 of the 21 colonies. However, in one colony, gynes and workers displayed multiple mtDNA haplotypes, indicating that nonnestmate recruitment had occurred. Overall the genetic structure within the majority of perennial colonies conformed to expectations based on the biology of V. germanica and kin selection theory for polygyne colonies; multiple reproductives successfully produced offspring and were recruited into their natal nests, thereby maintaining relatively high relatedness between interacting individuals.     

Mating behaviour of Rhytidoponera sp. 12 ants inferred from microsatellite analysis

In the queenless ponerine ant Rhytidoponera sp. 12, all workers have a spermatheca and functional ovaries and are potentially able to mate and reproduce. Within a colony gamergates may either be full sisters to each other (Type 1 colony), or they may not be full sisters but still be significantly related to each other (Type 2 colony) due to daughter gamergates reproducing in their natal colonies after mating. Despite many studies the mating behaviour of R. sp. 12 has been poorly understood. In this study, we used microsatellite markers to investigate intracolony relatednesses of male mates to the gamergates (bmq) and between male mates (bmm), and mating frequencies and mating patterns, using gamergate DNA and sperm DNA isolated from the spermathecae of gamergates from five colonies. Average bmm and bmq estimates for all five colonies studied were not significantly different from zero, suggesting that on average, within colonies, mating males were unrelated both to each other and to the gamergates. A low frequency (3%) of multiple mating by gamergates was detected. Multiple mating by individual males with sister gamergates within Type 1 colonies was also detected at 3% and could give rise to half-sister nestmate workers. Polygamy in R. sp. 12 might indicate local female-biased operational sex ratios despite the expectation of overall male biases. Our results concur with previous reports that gamergates mate within the colony or nearby, but indicate more diversity in mating patterns than previously indicated for this polygynous ponerine ant species.     

Comparative electrophoretic examination of the two European species of angler-fish (Lophiidae): Lophius piscatorius (L.) and Lophius budegassa (Spinola) and assessment of their genetic relationship

1. A multilocus electrophoretic examination of the genetic relationships between the two European species of angler-fish was carried out using starch gel electrophoresis. 2. At 4 gene loci fixation for different alleles separated Lophius piscatorius and L. budegassa while at an additional 5 loci, frequencies of shared alleles were significantly heterogeneous. 3. A mean genetic distance of I = 0.771 was calculated, corresponding to a mean genetic distance of D = 0.260 between these species. 4. This research identifies 7 polymorphic loci in L. piscatorius and 5 in L. budegassa which will potentially serve as genetic markers for examination of population structure.     

SUPPRESSION OF PHOTOTROPIC CIRCUS MOVEMENTS OF LIMAX BY STRYCHNINE

By injection with strychnine the phototropic circus movements of the slug Limax maximus may be suppressed, its phototropism abolished. The creeping activity of the foot is not in any essential way interferred with. Strychnine produces in Limax central nervous effects of the sort associated with its characteristic action. Hence, although an effect of the drug upon photoreceptors cannot be definitely excluded, the experimental result is held to demonstrate that in orientation during circus movements there occurs central "competition" between impulses resulting (1) in the release of pedal waves and (2) in the maintenance of a turning posture.     

ON BIOLOGICAL OXIDATIONS AS FUNCTION OF TEMPERATURE

1. The critical thermal increments are calculated for respiratory processes (O₂ consumption, CO₂ production) in various plants and animals. They are characteristically found to be of two, possibly three, types: µ = 11,500, and 16,100 or 16,700. The first is commonly encountered above 15°, the second below that temperature, but these relations may be reversed. (The value of µ may be significantly changed in inanition.) 2. For reduction of methylene blue by bacteria, through removal of H from succinic acid, µ = 16,700. This process (Quastel and Whetham, 1924) at constant temperature is a function of the hydroxyl ion concentration. The suggestive identity is pointed out of the critical increment for this reduction phenomenon with that deduced for biological respirations in which a dehydrogenation mechanism is supposed to be of widespread occurrence, and in connection with which Fe very likely has a catalytic rôle. The action of OH'' is believed to be revealed in the value µ = 11,500, frequently obtained in connection with respiration. 3. A somewhat lower µ (16,140) is associated with the oxidation of Fe'''', and may be compared with (1) that of respiration in sea urchin eggs, for which (Warburg) iron is catalyst, and (2) that for some simple reactions in which Fe is known to serve as catalyst; it is not found for oxidative reactions in which Fe is not involved. 4. The bearing of these findings is discussed in relation to the theory of functional analysis of concurrent catalyzed reactions in protoplasm. It is shown that for a number of activities in which the effects of respiration may safely be assumed, the values of the critical increments are consistent with those determined for processes of respiration. 5. The further development of these views may lead to an extremely important method of identifying controlling reactions in undisturbed living matter.     

THE WAVELENGTH SENSITIVITY FUNCTION FOR THE ZEBRA FINCH

With lights of different spectral compositions filtered from a white, the flicker response contours for the zebra finch are found to exhibit the same general kind of relationship between flicker excitation and wavelength as is found in the case of man ("cone" contours), with the same filters. The flicker contours for the zebra finch are simplex; the retina contains no rods. On a relative energy scale, with a flash cycle of fixed light-time percentage (10 per cent) the curve for yellow almost coincides with that for the white, the curve for red lies at much higher intensities, and the curves for blue-green and violet fall below that for the white by amounts increasing in that order. The maxima to which the curves rise and the slope constants are very nearly the same for all the spectral regions. For the bird the blue was a little less efficient, the green a little more efficient, and the red very much less efficient than in the case of man. It was deduced that in the retina of this diurnal bird the number of red oil globules should be comparatively small and that most of the globules should be greenish yellow. This was confirmed by direct examination.     

Single-molecule sequencing reveals the molecular basis of multidrug-resistance in ST772 methicillin-resistant Staphylococcus aureus

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-associated infection, but there is growing awareness of the emergence of multidrug-resistant lineages in community settings around the world. One such lineage is ST772-MRSA-V, which has disseminated globally and is increasingly prevalent in India. Here, we present the complete genome sequence of DAR4145, a strain of the ST772-MRSA-V lineage from India, and investigate its genomic characteristics in regards to antibiotic resistance and virulence factors.

Results

Sequencing using single-molecule real-time technology resulted in the assembly of a single continuous chromosomal sequence, which was error-corrected, annotated and compared to nine draft genome assemblies of ST772-MRSA-V from Australia, Malaysia and India. We discovered numerous and redundant resistance genes associated with mobile genetic elements (MGEs) and known core genome mutations that explain the highly antibiotic resistant phenotype of DAR4145. Staphylococcal toxins and superantigens, including the leukotoxin Panton-Valentinin Leukocidin, were predominantly associated with genomic islands and the phage φ-IND772PVL. Some of these mobile resistance and virulence factors were variably present in other strains of the ST772-MRSA-V lineage.

Conclusions

The genomic characteristics presented here emphasize the contribution of MGEs to the emergence of multidrug-resistant and highly virulent strains of community-associated MRSA. Antibiotic resistance was further augmented by chromosomal mutations and redundancy of resistance genes. The complete genome of DAR4145 provides a valuable resource for future investigations into the global dissemination and phylogeography of ST772-MRSA-V.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1599-9) contains supplementary material, which is available to authorized users.