Project description:Methanogens inhabit euxinic (sulfide-rich) or ferruginous (iron-rich) environments that promote the precipitation of transition metals as metal sulfides, such as pyrite, reducing metal or sulfur availability. Such environments have been common throughout Earth’s history raising the question as to how anaerobes obtain(ed) these elements for the synthesis of enzyme cofactors. Here, we show a methanogen can synthesize molybdenum nitrogenase metallocofactors from pyrite as the source of iron and sulfur, enabling nitrogen fixation. Pyrite-grown, nitrogen-fixing cells grow faster and require 25-fold less molybdenum than cells grown under euxinic conditions. Growth yields are 3 to 8 times higher in cultures grown under ferruginous relative to euxinic conditions. Physiological, transcriptomic, and geochemical data indicate these observations are due to sulfide-promoted metal limitation, in particular molybdenum. These findings suggest that molybdenum nitrogenase may have originated in a ferruginous environment that titrated sulfide to form pyrite, facilitating the availability of sufficient iron, sulfur, and molybdenum for cofactor biosynthesis.
Project description:Here we present the first characterisation of small RNAs in honey bee reproductive tissues. We conclude that small RNAs are likely to play an integral role in honey bee gametogenesis and reproduction and provide a plausible mechanism for parent-of origin-effects on gene expression and reproductive physiology. present in honey bee reproductive tissues: ovaries, spermatheca, semen, fertilised and unfertilised eggs, and testes.
Project description:Background The number of managed honey bee colonies has considerably decreased in many developed countries in recent years and the ectoparasitic mites are considered as major threats to honey bee colonies and health. However, their general biology remains poorly understood. Results We sequenced the genome and transcriptomes of Tropilaelaps mercedesae, the prevalent ectoparasitic mite infesting honey bees in Asia. The de novo assembled genome sequence (353 Mb) represents 53% of the estimated genome size because of the compression of repetitive sequences; nevertheless, we predicted 15,190 protein-coding genes which were well supported by the mite transcriptomes and proteomic dataes. Although amino acid substitutions have been accelerated within the conserved core genes in of two mites, T. mercedesae and Metaseiulus occidentalis, T. mercedesae has undergone the least gene family expansion and contraction between the seven arthropods we tested. The number of sensory system genes has been dramatically reduced; meanwhile, T. mercedesae may have evolved a specialized cuticle and water homeostasis mechanisms, as well as epigenetic control of gene expression for ploidy compensation between males and females., and water homeostasis. T. mercedesae contains all gene sets required to detoxify xenobiotics, enabling it to be miticide resistant. T. mercedesae is closely associated with a symbiotic bacteriuma (Rickettsiella grylli-like) and DWVdeformed wing virus (DWV), the most prevalent honey bee virus. The presence of DWV in both adult male and female mites was also confirmed by the proteomic analysis. Conclusions T. mercedesae has a very specialized life history and habitat as the ectoparasitic mite strictly dependsing on the honey bee inside the a stable colony. Thus, comparison of the genome and transcriptome sequences with those of a tick and free-living mites and tick has revealed the specific features of the genome shaped by interaction with the honey bee and colony environment. T. mercedesae, as well as Varroa destructor, genome and transcriptome sequences not only provide insights into the mite biology, but may also help to develop measures to control the most serious pests of the honey bee.
Project description:Social caste determination in the honey bee is assumed to be determined by the dietary status of the young larvae and translated into physiological and epigenetic changes through nutrient-sensing pathways. We have employed microRNA gene-microarray, and observed that both worker jelly and royal jelly showed dynamic changes in miRNA content during the 4th to 6th day of larval development . Adding specific miRNAs to royal jelly elicited significant changes in queen larval mRNA expression and in morphological characters of the emerging adult queen bee. We propose that miRNAs in the nurse bee secretions constitute an additional element in the regulatory control of caste determination in the honey bee.
Project description:Social caste determination in the honey bee is assumed to be determined by the dietary status of the young larvae and translated into physiological and epigenetic changes through nutrient-sensing pathways. We have employed Illumina/Solexa sequencing to examine the small RNA content in the bee larval food source, and show that worker jelly is enriched in miRNA complexity and abundance relative to royal jelly. The miRNA levels in worker jelly were 7-215 fold higher than in royal jelly, and both jellies showed dynamic changes in miRNA content during the 4th to 6th day of larval development. Adding specific miRNAs to royal jelly elicited significant changes in queen larval mRNA expression and in morphological characters of the emerging adult queen bee. We propose that miRNAs in the nurse bee secretions constitute an additional element in the regulatory control of caste determination in the honey bee.