Summary

Queens, homozygous for three marker genes, were inseminated with eight different types of semen, each carrying one combination of the markers. Intracolonial worker relationship (ř_c) was estimated by genotype frequencies in the offspring of the experimental queens. ř_c was larger than under random distribution of semen types in the spermatheca. Estimates of most quantitative genetical parameters will be more accurate using the presented estimator for intracolonial relationship. The insemination order affected genotype frequencies in the offspring, suggesting a weak ‘last male advantage’. There was, however, no evidence of intra spermathecal sperm competition.

Actinobacteria within the acI lineage are often numerically dominating in freshwater ecosystems, where they can account for >50% of total bacteria in the surface water. However, they remain uncultured to date. We thus set out to use single-cell genomics to gain insights into their genetic make-up, with the aim of learning about their physiology and ecological niche. A representative from the highly abundant acI-B1 group was selected for shotgun genomic sequencing. We obtained a draft genomic sequence in 75 larger contigs (sum=1.16 Mb), with an unusually low genomic G+C mol% (∼42%). Actinobacteria core gene analysis suggests an almost complete genome recovery. We found that the acI-B1 cell had a small genome, with a rather low percentage of genes having no predicted functions (∼15%) as compared with other cultured and genome-sequenced microbial species. Our metabolic reconstruction hints at a facultative aerobe microorganism with many transporters and enzymes for pentoses utilization (for example, xylose). We also found an actinorhodopsin gene that may contribute to energy conservation under unfavorable conditions. This project reveals the metabolic potential of a member of the global abundant freshwater Actinobacteria.

In sexual reproduction, ejaculate components that males transfer into the females vary because of various factors. For male honey bees, the entirety of their sperm is stored in the seminal vesicles until the first copulation with a female and subsequent ejaculation, after which the male will die. Therefore, we can evaluate age-related ejaculate alterations by investigating internal sexual organ changes with age. This study found that seminal vesicle wet weight decreased following sperm transfer from testes to seminal vesicles, while mucus gland weight was unchanged, thus resulting in increased sperm density in the seminal vesicles. This suggests that the decrease of seminal fluid in the seminal vesicles may be the underlying cause for age-related ejaculate component alterations.

The early history of life harbours many unresolved evolutionary questions, none more important than the genomic origin and cellular evolution of eukaryotes. An issue central to eukaryote origin concerns the position of eukaryotes in the tree of life and the relationship of the host lineage that acquired the mitochondrion some two billion years ago to lineages of modern-day archaea. Recent analyses indicate that the host lineage branches within the Archaea, prompting the search for novel archaeal lineages that can improve our understanding of the cellular evolution of eukaryotes. Here we give a brief review of the studies on Archaea, the tree of life and the cellular evolution of eukaryotes, which is followed by an overview of recent progress fueled by new genomic technologies and recent status of archaeal research in China. Future directions for the study of early evolution are considered.

Microorganisms and the viruses that infect them are the most numerous biological entities on Earth and enclose its greatest biodiversity and genetic reservoir. With strength in their numbers, these microscopic organisms are major players in the cycles of energy and matter that sustain all life. Scientists have only scratched the surface of this vast microbial world through culture-dependent methods. Recent developments in generating metagenomes, large random samples of nucleic acid sequences isolated directly from the environment, are providing comprehensive portraits of the composition, structure, and functioning of microbial communities. Moreover, advances in metagenomic analysis have created the possibility of obtaining complete or nearly complete genome sequences from uncultured microorganisms, providing important means to study their biology, ecology, and evolution. Here we review some of the recent developments in the field of metagenomics, focusing on the discovery of genetic novelty and on methods for obtaining uncultured genome sequences, including through the recycling of previously published datasets. Moreover we discuss how metagenomics has become a core scientific tool to characterize eco-evolutionary patterns of microbial ecosystems, thus allowing us to simultaneously discover new microbes and study their natural communities. We conclude by discussing general guidelines and challenges for modeling the interactions between uncultured microorganisms and viruses based on the information contained in their genome sequences. These models will significantly advance our understanding of the functioning of microbial ecosystems and the roles of microbes in the environment.

A colony-level phenotype was used to map the major sex determination locus (designatedX) in the honey bee (Apis mellifera). Individual queen bees (reproductive females) were mated to single drones (fertile males) by instrumental insemination. Haploid drone progeny of an F1 queen were each backcrossed to daughter queens from one of the parental lines. Ninety-eight of the resulting colonies containing backcross progeny were evaluated for the trait ‘low brood-viability’ resulting from the production of diploid drones that were homozygous atX. DNA samples from the haploid drone fathers of these colonies were used individually in polymerase chain reactions (PCR) with 10-base primers. These reactions generated random amplified polymorphic DNA (RAPD) markers that were analyzed for cosegregation with the colony-level phenotype. One RAPD marker allele was shared by 22 of 25 drones that fathered low brood-viability colonies. The RAPD marker fragment was cloned and partially sequenced. Two primers were designed that define a sequence-tagged site (STS) for this locus. The primers amplified DNA marker fragments that cosegregated with the original RAPD marker. In order to more precisely estimate the linkage betweenX and the STS locus, another group of bees consisting of progeny from one of the low-brood viability colonies was used in segregation analysis. Four diploid drones and 181 of their diploid sisters (workers, nonfertile females) were tested for segregation of the RAPD and STS markers. The cosegregating RAPD and STS markers were codominant due to the occurrence of fragment-length alleles. The four diploid drones were homozygous for these markers but only three of the 181 workers were homozygotes (recombinants). Therefore the distance betweenX and the STS locus was estimated at 1.6 cM. An additional linked marker was found that was 6.6 cM from the STS locus.

We tested whether flow cytometry can be used for assessment of viability of honey bee (Apis mellifera) sperm. The method was used to detect possible competition between the sperm of different drones. The flow cytometry analysis of semen stained with SYBR-14/propidium iodide revealed significant differences between fresh and freeze-thawed samples. The identification of populations corresponding to viable and nonviable sperm allowed us to assess the sperm viability. The comparison of single-drone semen with mixed semen of two unrelated drones showed that sperm viability was not affected by mixing, but there were differences between mixed and unmixed semen in side scatter, which correlates with shape and optical homogeneity of particles. The proportion of particles in different populations also was affected by mixing of the semen. The results suggest that there are interactions between ejaculates of different drones, possibly related to sperm competition.

Summary

A deterministic model is presented which shows that multiple mating reduces the conflict between workers and queen in the optimal investment ratio in each sex. The natural risk of the nuptual flights of honeybee queens fits well into the theoretically determined risk when queens tend to optimize the numbers of drones with which they mate.