In the honey bee, Apis mellifera, colonies are composed of one queen, thousands of female workers, and a few thousand seasonal males (drones) that are reared only during the reproductive season when colony resources are plentiful. Despite their transient presence in the hive, drones have the important function of mating with virgin queens, transferring their colony’s genes to their mates for the production of fertilized, worker-destined eggs. Therefore, factors affecting drone health and reproductive competency may directly affect queen fitness and longevity, having great implications at the colony level. Several environmental and in-hive conditions can affect the quality and viability of drones in general and their sperm in particular. Here we review the extant studies that describe how environmental factors including nutrition, temperature, season, and age may influence drone reproductive health. We also review studies that describe other factors, such as pesticide exposure during and after development, that may also influence drone reproductive quality. Given that sperm development in drones is completed during pupation prior to adult emergence, particular attention needs to be paid to these factors during drone development, not just during adulthood. The present review showcases a growing body of evidence indicating that drones are very sensitive to environmental fluctuations and that these factors cause drones to underperform, potentially compromising the reproductive health of their queen mates, as well as the overall fitness of their colony.

Aerobic methane-oxidizing bacteria (methanotrophs) have the unique ability to grow on methane as their sole source of carbon and energy. They are ubiquitous in the environment and play a major role in the removal of the greenhouse gas methane from the biosphere before it is released into the atmosphere. The ability to drive oxygen-dependent methane oxidation was once assumed to be an exceptional property of a very restricted set of microbes belonging to two classes of Proteobacteria: Alphaproteobacteria and Gammaproteobacteria. While Proteobacteria still form the foundation of the methanotrophic landscape in many ecosystems, the ability to oxidize methane has also been demonstrated in the microbial phyla Verrucomicrobia and Candidatus Methylomirabilis oxyfera (phylum NC10). Over the years various methanotrophs have also been isolated, including facultative methanotrophs, extremophile species, and anaerobes, thus expanding both the taxonomic diversity and physiological range of methanotrophy. In addition, a number of cross-species interactions that enable efficient methane utilization have been identified, changing the way we view mechanisms of methane utilization. Finally, a thorough revision of core metabolic pathways has been made, and whole-genome metabolic models have been constructed, which facilitate the metabolic engineering of methanotrophic bacteria and expand the potential for their biotechnological applications.

The high altitude bee, Apis laboriosa Smith significantly differs from the close phylogenetic relative A. dorsata Fabricius in colour and shape of the abdomen, the endophalli of male genitalia, nucleotide sequence of the mitochondrial protein coding genes, chemical constituents of the cephalic and abdominal endocrine glands, nesting pattern, foraging and mating behaviour to distinguish them as separate species. They are found to construct single combed exposed nests under rock ledges in altitude ranging from 1200 to 3500 m above mean sea level from northern India to northern Vietnam. Current research trend shows the need of special attention for maximum possible and better quality agricultural and horticultural yield using A. laboriosa as it is known to pollinate a number of crops and fruits. General aspects of A. laboriosa to create sensitivity towards conservation of this species native to high altitude Himalayan foothills before being stressed by honey hunting, changing agricultural practices and crowding of natural enemies have also been focussed here.

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.

Queen reproductive potential (=quality) impacts the health and productivity of honey bee colonies. To determine the factors that affect reproductive quality during development, we tested queens produced under larval treatments by supplementing the diet with juvenile hormone (JH), additional sugars, or both, compared to untreated control. Furthermore, we varied the age of the larvae that were grafted (1 and 3 days old). We analyzed newly emerged virgin queens for their morphological characters as proxies for their reproductive potential. We found that the application of a sugar-enriched diet in combination with JH application onto 1st instar queen larvae produced higher-quality queens, while for 3rd instar larvae only the JH treatment resulted in increasing queen quality. For mated queens, those treated with JH plus supplemented sugars showed a significantly higher sperm count and sperm viability. Our findings demonstrate that honey bee queen reproductive potential can be increased through diet supplementation.

Exceptional natural phenomena, such as those that occur during a total solar eclipse, provide unique opportunities to study animal behavior outside the naturally evolved context, which can be informative in more general terms. Circumstantial descriptions of abnormal animal behavior during solar eclipses abound, although scientific studies conducted during an eclipse are relatively rare due to inherent logistical difficulties. Here, honey bee foraging and homing behavior were studied during the total solar eclipse of August 21, 2017. In the first experiment, we studied foraging behavior of honey bees during the progression of the solar eclipse and found that the foraging activity drastically decreased but did not completely cease during the totality of the eclipse, in contrast to previous reports of complete cessation. The data indicate that the level of ambient light can largely overrule the internal circadian rhythm of foraging honey bees. Furthermore, colonies with a higher need for foraging decreased their foraging activity less than satiated colonies, consistent with the hypothesis that individual foraging decisions may be influenced by colony state, which affects cost-benefit analyses. In a second experiment, the temporal dynamics of homing of released workers and drones was compared in periods before, during, and after the solar eclipse. During the totality of the eclipse, very few bees arrived back at their hive, while homing before the total eclipse was accelerated, particularly in drones. The results suggest that, while the homing abilities of honey bees are not compromised until the sun is completely eclipsed, they may still interpret the diminishing light as an indicator of deteriorating flight conditions. Our unique study provides some insight into the control of honey bee foraging behavior when external cues and internal circadian rhythms are at odds, lent support to the notion that food deprivation can lead to riskier foraging, and indicated that homing in honey bees is possible even with very small amounts of sunlight.

Archaea have been recognized as a major domain of life since the 1970s and occupy a key position in the tree of life. Recent advances in culture-independent approaches have greatly accelerated the research son Archaea. However, many hypotheses concerning the diversity, physiology, and evolution of archaea are waiting to be confirmed by culture-base experiments. Consequently, archaeal isolates are in great demand. On the other hand, traditional approaches of archaeal cultivation are rarely successful and require urgent improvement. Here, we review the current practices and applicable microbial cultivation techniques, to inform on potential strategies that could improve archaeal cultivation in the future. We first summarize the current knowledge on archaeal diversity, with an emphasis on cultivated and uncultivated lineages pertinent to future research. Possible causes for the low success rate of the current cultivation practices are then discussed to propose future improvements. Finally, innovative insights for archaeal cultivation are described, including (1) medium refinement for selective cultivation based on the genetic and transcriptional information; (2) consideration of the up-to-date archaeal culturing skills; and (3) application of multiple cultivation techniques, such as co-culture, direct interspecies electron transfer (DIET), single-cell isolation, high-throughput culturing (HTC), and simulation of the natural habitat. Improved cultivation efforts should allow successful isolation of as yet uncultured archaea, contributing to the much-needed physiological investigation of archaea.

Background

Obligate sulfur oxidizing chemolithoauthotrophic strains of Hydrogenovibrio crunogenus have been isolated from multiple hydrothermal vent associated habitats. However, a hydrogenase gene cluster (encoding the hydrogen converting enzyme and its maturation/assembly machinery) detected on the first sequenced H. crunogenus strain (XCL-2) suggested that hydrogen conversion may also play a role in this organism. Yet, numerous experiments have underlined XCL-2’s inability to consume hydrogen under the tested conditions. A recent study showed that the closely related strain SP-41 contains a homolog of the XCL-2 hydrogenase (a group 1b [NiFe]-hydrogenase), but that it can indeed use hydrogen. Hence, the question remained unresolved, why SP-41 is capable of using hydrogen, while XCL-2 is not.

Results

Here, we present the genome sequence of the SP-41 strain and compare it to that of the XCL-2 strain. We show that the chromosome of SP-41 codes for a further hydrogenase gene cluster, including two additional hydrogenases: the first appears to be a group 1d periplasmic membrane-anchored hydrogenase, and the second a group 2b sensory hydrogenase. The region where these genes are located was likely acquired horizontally and exhibits similarity to other Hydrogenovibrio species (H. thermophilus MA2-6 and H. marinus MH-110 ^T) and other hydrogen oxidizing Proteobacteria (Cupriavidus necator H16 and Ghiorsea bivora TAG-1 ^T). The genomes of XCL-2 and SP-41 show a strong conservation in gene order. However, several short genomic regions are not contained in the genome of the other strain. These exclusive regions are often associated with signs of DNA mobility, such as genes coding for transposases. They code for transport systems and/or extend the metabolic potential of the strains.

Conclusions

Our results suggest that horizontal gene transfer plays an important role in shaping the genomes of these strains, as a likely mechanism for habitat adaptation, including, but not limited to the transfer of the hydrogen conversion ability.

This chapter focuses on how metagenomic data are applied to examine the genomic heterogeneity of natural microbial populations. It highlights the opportunities and challenges inherent to the approach and describes recently developed methods to maximally leverage the potential of these datasets while tackling some of the challenges. We describe how performing population genomic analyses using metagenomic data allows (1) resolution of ecologically and genetically cohesive populations in the environment, (2) tracking of evolutionary processes within them, and (3) application of metatranscriptomic and metaproteomic analyses to determine the in situ physiology of distinct populations. While challenges remain that are inherent to the approach, the current wave of new bioinformatic tools is starting to realize the theoretical potential of metagenomics to peer into the spatiotemporal dynamics of the genetic structure of natural populations.