New discovery of a large-sized Tetraconodon (Artiodactyla, Suidae) from the lower part of the Irrawaddy Formation, Myanmar

New fossil dentitions of a large-sized Tetraconodon (Mammalia, Artiodactyla, Suidae) were discovered from the lower part of the Irrawaddy Formation, Migyaungye Township, Magway Division, central Myanmar. These specimens are the largest among the Tetraconodon specimens ever found in Myanmar. The molar dimensions of these specimens are similar with those of Tetraconodon magnus but are smaller in the dimensions of last two premolars than T. magnus. Therefore, we assigned these specimens as Tetraconodon sp. cf. T. magnus. The occurrence of a large Tetraconodon confirms an Upper Miocene age for the lower part of the Irrawaddy Formation

Discovery of Propotamochoerus (Artiodactyla, Suidae) from the Neogene of Myanmar

Dento-gnathic specimens of Propotamochoerus (Mammalia, Artiodactyla, Suidae) were discovered from the upper Miocene and lower Pliocene of the Irrawaddy Group, central Myanmar. These specimens were identified as Propotamochoerus hysudricus and Propotamochoerus sp. cf. P. hysudricus. The discovery of P. cf. hysudricus from the lower Pliocene indicates a younger stratigraphic position of this genus. Small size of the premolars in the lower Pliocene specimens possibly suggests an intermediate stage of dental evolution for this form

Mitochondrial pseudogenes in the nuclear genome of Aedes aegypti mosquitoes: implications for past and future population genetic studies

<p>Abstract</p> <p>Background</p> <p>Mitochondrial DNA (mtDNA) is widely used in population genetic and phylogenetic studies in animals. However, such studies can generate misleading results if the species concerned contain nuclear copies of mtDNA (Numts) as these may amplify in addition to, or even instead of, the authentic target mtDNA. The aim of this study was to determine if Numts are present in <it>Aedes aegypti </it>mosquitoes, to characterise any Numts detected, and to assess the utility of using mtDNA for population genetics studies in this species.</p> <p>Results</p> <p>BLAST searches revealed large numbers of Numts in the <it>Ae. aegypti </it>nuclear genome on 146 supercontigs. Although the majority are short (80% < 300 bp), some Numts are almost full length mtDNA copies. These long Numts are not due to misassembly of the nuclear genome sequence as the Numt-nuclear genome junctions could be recovered by amplification and sequencing. Numt evolution appears to be a complex process in <it>Ae. aegypti </it>with ongoing genomic integration, fragmentation and mutation and the secondary movement of Numts within the nuclear genome.</p> <p>The PCR amplification of the putative mtDNA nicotinamide adenine dinucleotide dehydrogenase subunit 4 (<it>ND4</it>) gene from 166 Southeast Asian <it>Ae. aegypti </it>mosquitoes generated a network with two highly divergent lineages (clade 1 and clade 2). Approximately 15% of the <it>ND4 </it>sequences were a composite of those from each clade indicating Numt amplification in addition to, or instead of, mtDNA. Clade 1 was shown to be composed at least partially of Numts by the removal of clade 1-specific bases from composite sequences following enrichment of the mtDNA. It is possible that all the clade 1 sequences in the network were Numts since the clade 2 sequences correspond to the known mitochondrial genome sequence and since all the individuals that produced clade 1 sequences were also found to contain clade 2 mtDNA-like sequences using clade 2-specific primers. However, either or both sets of clade sequences could have Numts since the BLAST searches revealed two long Numts that match clade 2 and one long Numt that matches clade 1. The substantial numbers of mutations in cloned <it>ND4 </it>PCR products also suggest there are both recently-derived clade 1 and clade 2 Numt sequences.</p> <p>Conclusion</p> <p>We conclude that Numts are prevalent in <it>Ae. aegypti </it>and that it is difficult to distinguish mtDNA sequences due to the presence of recently formed Numts. Given this, future population genetic or phylogenetic studies in <it>Ae. aegypti </it>should use nuclear, rather than mtDNA, markers.</p

Co-occurrence of Point Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Aedes aegypti Populations in Myanmar

Background:Single amino acid substitutions in the voltage-gated sodium channel associated with pyrethroid resistance constitute one of the main causative factors of knockdown resistance in insects. The kdr gene has been observed in several mosquito species; however, point mutations in the para gene of Aedes aegypti populations in Myanmar have not been fully characterized. The aim of the present study was to determine the types and frequencies of mutations in the para gene of Aedes aegypti collected from used tires in Yangon City, Myanmar.Methodology/Principal Findings:We determined high pyrethroid resistance in Aedes aegypti larvae at all collection sites in Yangon City, by using a simplified knockdown bioassay. We showed that V1016G and S989P mutations were widely distributed, with high frequencies (84.4% and 78.8%, respectively). By contrast, we were unable to detect I1011M (or I1011V) or L1014F mutations. F1534C mutations were also widely distributed, but with a lower frequency than the V1016G mutation (21.2%). High percentage of co-occurrence of the homozygous V1016G/S989P mutations was detected (65.7%). Additionally, co-occurrence of homozygous V1016G/F1534C mutations (2.9%) and homozygous V1016G/F1534C/S989P mutations (0.98%) were detected in the present study.Conclusions/Significance:Pyrethroid insecticides were first used for malaria control in 1992, and have since been constantly used in Myanmar. This intensive use may explain the strong selection pressure toward Aedes aegypti, because this mosquito is generally a domestic and endophagic species with a preference for indoor breeding. Extensive use of DDT for malaria control before the use of this chemical was banned may also explain the development of pyrethroid resistance in Aedes aegypti

Discovery of chalicothere and Dorcabune from the upper part (lower Pleistocene) of the Irrawaddy Formation, Myanmar

We describe fossil dental specimens of a chalicothere (Perissodactyla, Mammalia) and Dorcabune (Tragulidae, Artiodactyla, Mammalia) discovered from the upper part (lower Pleistocene) of the Irrawaddy Formation at Gwebin area, central Myanmar. The specimens described here consist of three molar fossils: a left upper molar and a left M, or M 2 of a chalicothere (cf. Nestoritherium sp.); and a right M3 of Dorcabune sp. Although fragmentally, this is the first discovery of the Chalicotheriidae and Dorcabune from the upper part of the Irrawaddy Formation

A preliminary report on the freshwater molluscan fossils from Myanmar

Three named species and nine indeterminate species of freshwater molluscan fossils are found from the Eocene, Mio-Pleistocene, and Holocene of central Myanmar. The Eocene fossils are found from the Pondaung Formation and consist of an indeterminate viviparid gastropod, indicating a shallow-water environment. The Mio-Pleistocene fossils were found from the Irrawaddy Beds and consists of Melanoides sp. indet., Brotia costula, Indonaia? sp. indet., Radiatula sp. cf. Radiatula lima, Lamellidens sp. indet., Parreysia favidens, and P. pernodulosa. The molluscan fauna of the Irrawaddy Beds is characterized by occurrence of comparative species in Myanmar and in South Asia, indicating that a similar water system with present one in that time. The Holocene fossils were found from the Buddaw Zinaw Cave deposit and consist of Margarya sp. and Brotia costula. Among the Holocene fossils, Margarya is a representative genus of the recent freshwater molluscan fauna of Yunnan (southern China), indicating that a water system extended between Yunnan and central Myanmar in that time

Spatial genetic structure of Aedes aegypti mosquitoes in mainland Southeast Asia

Aedes aegypti mosquitoes originated in Africa and are thought to have spread recently to Southeast Asia, where they are the major vector of dengue. Thirteen microsatellite loci were used to determine the genetic population structure of A. aegypti at a hierarchy of spatial scales encompassing 36 sites in Myanmar, Cambodia and Thailand, and two sites in Sri Lanka and Nigeria. Low, but significant, genetic structuring was found at all spatial scales (from 5 to >2000 km) and significant F(IS) values indicated genetic structuring even within 500 m. Spatially dependent genetic-clustering methods revealed that although spatial distance plays a role in shaping larger-scale population structure, it is not the only factor. Genetic heterogeneity in major port cities and genetic similarity of distant locations connected by major roads, suggest that human transportation routes have resulted in passive long-distance migration of A. aegypti. The restricted dispersal on a small spatial scale will make localized control efforts and sterile insect technology effective for dengue control. Conversely, preventing the establishment of insecticide resistance genes or spreading refractory genes in a genetic modification strategy would be challenging. These effects on vector control will depend on the relative strength of the opposing effects of passive dispersal

A revision of Tetraconodon (Mammalia, Artiodactyla, Suidae) from the Miocene of Myanmar and description of a new species.

We describe five new dento-gnathic specimens of Tetraconodon, a genus of Miocene tetraconodontine suid (Mammalia, Artiodactyla), discovered in Myanmar (FBurma). In Myanmar, we recognized three distinct species of Tetraconodon (T. minor, T. intermedius and T. malensis sp. nov.) and one specifi- cally undetermined specimen, which is here named Tetraconodon sp. cf. T. intermedius. The new species, T. malensis, has characteristics of Tetraconodon, such as extremely enlarged P4 and simple and relatively small M3. It is distinct from the other Tetraconodon species in being much smaller, suggesting that it is the most primitive known Tetraconodon species. The dental size and characteristics of T. malensis suggest that Tetraconodon was derived during the late middle Miocene from the early middle Miocene Conohyus sindiensis, which was discovered in the Siwalik Group of Indo-Pakistan and Nepal and has also been found in the middle Miocene deposits of Thailand, or a close relative. The discovery of the most primitive form in Myanmar suggests that Tetraconodon may have originated in Myanmar

Species composition of hairtails (Trichiuridae) in Myanmar

Hairtails (family Trichiuridae) are an important group of fish for coastal fisheries worldwide. In the view to reiterate the need of management of hairtails found in the Republic of the Union of Myanmar, the species composition of hairtails was investigated according to the morphological characteristics and DNA barcoding of mitochondrial cytochrome c oxidase subunit I gene. A total of 95 individual landed fish were sampled from fish markets in Yangon and Myeik. The hairtails were treated similarly to the group without species distinction at the fish markets, which consisted of five species from three genera, namely Trichiurus sp., Lepturacanthus savala, Lepturacanthus sp., Eupleurogrammus sp., and Eupleurogrammus muticus. Further studies on the biological characteristics and taxonomies are needed to establish improved approach of identifying with such fishery species in Myanmar

Discovery of propotamochoerus (Artiodactyla, Suidae) from the Neogene of Myanmar

Dento-gnathic specimens of Propotamochoerus (Mammalia, Artiodactyla, Suidae) were discovered from the upper Miocene and lower Pliocene of the Irrawaddy Group, central Myanmar. These specimens were identified as Propotamochoerus hysudricus and Propotamochoerus sp. cf. P. hysudricus. The discovery of P. cf. hysudricus from the lower Pliocene indicates a younger stratigraphic position of this genus. Small size of the premolars in the lower Pliocene specimens possibly suggests an intermediate stage of dental evolution for this form