Complete Genome of Rose Myrtle, Rhodomyrtus tomentosa, and Its Population Genetics in Thai Peninsula.

Several parts of rose myrtle, Rhodomyrtus tomentosa, exhibited profound antibacterial and anti-inflammatory activities, suggesting its potential in healthcare and cosmetics applications. During the past few years, the demand for biologically active compounds in the industrial sectors increased. Therefore, gathering comprehensive information on all aspects of this plant species is essential. Here, the genome sequencing using short and long reads was used to understand the genome biology of R. tomentosa. Inter-simple sequence repeats (ISSR) and simple sequence repeats (SSR) markers, and geometric morphometrics of the leaves of R. tomentosa collected across Thai Peninsula, were determined for population differentiation analysis. The genome size of R. tomentosa was 442 Mb, and the divergence time between R. tomentosa and Rhodamnia argentea, the white myrtle of eastern Australia, was around 15 million years. No population structure was observed between R. tomentosa on the eastern and western sides of the Thai Peninsula using the ISSR and SSR markers. However, significant differences in leaf size and shape of R. tomentosa were observed in all locations.

Wolbachia endosymbiotic bacteria alter the gut microbiome in the fly Drosophila nigrosparsa.

Wolbachia are known to cause reproductive manipulations and in some arthropod species, Wolbachia were reported to cause changes in gut microbiome. However, the effects of Wolbachia bacteria on the microbiomes of their hosts, including Drosophila flies, have not been fully accessed. Here, we checked the bacterial microbiome in guts of Wolbachia-uninfected and of Wolbachia-infected Drosophila nigrosparsa, both separated into a bleach-only (embryos bleached) and a gnotobiotic (embryos bleached and inoculated with bacteria) treatment. We observed a clear separation between the Wolbachia-infected and the Wolbachia-uninfected samples, and the infected samples had higher variation in alpha diversity than the uninfected ones. There were reductions in the abundances of Proteobacteria (Pseudomonadota), especially Acetobacter, in the infected samples of both treatments. These findings highlight that Wolbachia change the gut microbiome in D. nigrosparsa as well as that the interactions between Wolbachia and bacteria like Acetobacter need to be investigated.

Low Endosymbiont Incidence in Drosophila Species Across Peninsula Thailand.

Arthropods are known to harbor several endosymbionts, such as Cardinium, Rickettsia, Spiroplasma, and Wolbachia. Wolbachia, for example, are the most widespread known endosymbionts in the world, which are found in about half of all arthropod species. To increase their transmission, these endosymbionts must manipulate their hosts in several ways such as cytoplasmic incompatibility and male killing. In tropical regions, endosymbiont diversity has not been studied exhaustively. Here, we checked four endosymbionts, including Cardinium, Rickettsia, Spiroplasma, and Wolbachia, in eleven Drosophila species found in Thai Peninsula. The Wolbachia strain wRi-like was found in all populations of Drosophila ananassae and Drosophila simulans. Furthermore, we found two new strains, wMalA and wMalB, in two populations of Drosophila malerkotliana. Besides Wolbachia, we did not find any of the above endosymbionts in all fly species. This work reveals the hidden diversity of endosymbionts in Drosophila and is the first exhaustive study on Drosophila in the region.

Analyses of locomotion, wing morphology, and microbiome in Drosophila nigrosparsa after recovery from antibiotics.

Antibiotics, such as tetracycline, have been frequently used to cure arthropods of Wolbachia endosymbionts. After the symbionts have been removed, the hosts must recover for some generations from the side effects of the antibiotics. However, most studies do not assess the direct and indirect longer-term effects of antibiotics used to remove Wolbachia, which may question the exact contribution of this endosymbiont to the effects observed. Here, we used the fly Drosophila nigrosparsa treated or not with tetracycline for three generations followed by two generations of recovery to investigate the effects of this antibiotic on the fly locomotion, wing morphology, and the gut microbiome. We found that antibiotic treatment did not affect fly locomotion two generations after being treated with the antibiotic. In addition, gut-microbiome restoration was tested as a more efficient solution to reduce the potential side effects of tetracycline on the microbiome. There was no significant difference in alpha diversity between gut restoration and other treatments, but the abundance of some bacterial taxa differed significantly between the gut-restoration treatment and the control. We conclude that in D. nigrosparsa the recovery period of two generations after being treated with the antibiotic is sufficient for locomotion, and suggest a general assessment of direct and indirect effects of antibiotics after a particular recovery time.

Differential gene expression in Drosophila melanogaster and D. nigrosparsa infected with the same Wolbachia strain.

Wolbachia are maternally inherited endosymbionts that infect nearly half of all arthropod species. Wolbachia manipulate their hosts to maximize their transmission, but they can also provide benefits such as nutrients and resistance against viruses to their hosts. The Wolbachia strain wMel was recently found to increase locomotor activities and possibly trigger cytoplasmic incompatibility in the transinfected fly Drosophila nigrosparsa. Here, we investigated, in females of both D. melanogaster and D. nigrosparsa, the gene expression between animals uninfected and infected with wMel, using RNA sequencing to see if the two Drosophila species respond to the infection in the same or different ways. A total of 2164 orthologous genes were used. The two fly species responded to the infection in different ways. Significant changes shared by the fly species belong to the expression of genes involved in processes such as oxidation-reduction process, iron-ion binding, and voltage-gated potassium-channel activity. We discuss our findings also in the light of how Wolbachia survive within both the native and the novel host.

Wolbachia affect behavior and possibly reproductive compatibility but not thermoresistance, fecundity, and morphology in a novel transinfected host, Drosophila nigrosparsa.

Wolbachia, intracellular endosymbionts, are estimated to infect about half of all arthropod species. These bacteria manipulate their hosts in various ways for their maximum benefits. The rising global temperature may accelerate species migration, and thus, horizontal transfer of Wolbachia may occur across species previously not in contact. We transinfected and then cured the alpine fly Drosophila nigrosparsa with Wolbachia strain wMel to study its effects on this species. We found low Wolbachia titer, possibly cytoplasmic incompatibility, and an increase in locomotion of both infected larvae and adults compared with cured ones. However, no change in fecundity, no impact on heat and cold tolerance, and no change in wing morphology were observed. Although Wolbachia increased locomotor activities in this species, we conclude that D. nigrosparsa may not benefit from the infection. Still, D. nigrosparsa can serve as a host for Wolbachia because vertical transmission is possible but may not be as high as in the native host of wMel, Drosophila melanogaster.

Wolbachia megadiversity: 99% of these microorganismic manipulators unknown.

Wolbachia (Alphaproteobacteria) are the most widespread endosymbionts of arthropods, manipulating their hosts by various means to maximize the number of host individuals infected. Based on quantitative analyzes of the published literature from Web of Science® and of DNA sequences of arthropod-hosted Wolbachia from GenBank, we made plausible that less than 1% of the expected 100 000 strains of Wolbachia in arthropods is known. Our findings suggest that more and globally better coordinated efforts in screening arthropods are needed to explore the true Wolbachia diversity and to help us understand the ecology and evolution of these host-endosymbiont interactions.

Genetic species identification and population structure of Halophila (Hydrocharitaceae) from the Western Pacific to the Eastern Indian Ocean.

BACKGROUND: The Indo-Pacific region has the largest number of seagrass species worldwide and this region is considered as the origin of the Hydrocharitaceae. Halophila ovalis and its closely-related species belonging to the Hydrocharitaceae are well-known as a complex taxonomic challenge mainly due to their high morphological plasticity. The relationship of genetic differentiation and geographic barriers of H. ovalis radiation was not much studied in this region. Are there misidentifications between H. ovalis and its closely related species? Does any taxonomic uncertainty among different populations of H. ovalis persist? Is there any genetic differentiation among populations in the Western Pacific and the Eastern Indian Ocean, which are separated by the Thai-Malay peninsula? Genetic markers can be used to characterize and identify individuals or species and will be used to answer these questions. RESULTS: Phylogenetic analyses of the nuclear ribosomal internal transcribed spacer region based on materials collected from 17 populations in the Western Pacific and the Eastern Indian Ocean showed that some specimens identified as H. ovalis belonged to the H. major clade, also supported by morphological data. Evolutionary divergence between the two clades is between 0.033 and 0.038, much higher than the evolutionary divergence among H. ovalis populations. Eight haplotypes were found; none of the haplotypes from the Western Pacific is found in India and vice versa. Analysis of genetic diversity based on microsatellite analysis revealed that the genetic diversity in the Western Pacific is higher than in the Eastern Indian Ocean. The unrooted neighbor-joining tree among 14 populations from the Western Pacific and the Eastern Indian Ocean showed six groups. The Mantel test results revealed a significant correlation between genetic and geographic distances among populations. Results from band-based and allele frequency-based approaches from Amplified Fragment Length Polymorphism showed that all samples collected from both sides of the Thai-Malay peninsula were clustered into two clades: Gulf of Thailand and Andaman Sea. CONCLUSIONS: Our study documented the new records of H. major for Malaysia and Myanmar. The study also revealed that the Thai-Malay peninsula is a geographic barrier between H. ovalis populations in the Western Pacific and the Eastern Indian Ocean.