2016 Vol. 37, No. 5

Full issue
2016, 37(5)
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Lampreys belong to the superclass Cyclostomata and represent the most ancient group of vertebrates. Existing for over 360 million years, they are known as living fossils due to their many evolutionally conserved features. They are not only a keystone species for studying the origin and evolution of vertebrates, but also one of the best models for researching vertebrate embryonic development and organ differentiation. From the perspective of genetic information, the lamprey genome remains primitive compared with that of other higher vertebrates, and possesses abundant functional genes. Through scientific and technological progress, scientists have conducted in-depth studies on the nervous, endocrine, and immune systems of lampreys. Such research has significance for understanding and revealing the origin and evolution of vertebrates, and could contribute to a greater understanding of human diseases and treatments. This review presents the current progress and significance of lamprey research.
In recent years, wildlife conservation has attracted great public attention. However, substantial distinctions can be found in the prevailing concepts of wildlife conservation, particularly with the recent notion that emphasizes animal rights. Wildlife welfare and wildlife rights are not synonymous, with welfare more compatible with the reasonable and legal utilization of wildlife. The key to scientific wildlife conservation is the appropriate awareness and appreciation of the relationship between wildlife conservation and utilization and the theoretical basis of holism. Nevertheless, rational biases regarding the public's understanding of wildlife conservation and the spread of information via social media still exist. As such, expansion of the concept of scientific wildlife conservation requires the application of several measures. Wildlife conservation researchers should be regarded as the most important disseminators of scientifically-based information, with education in schools and universities of growing importance. Furthermore, the media should shoulder the social responsibility for the accurate dissemination of conservation information.
Biological invasion is a pervasive negative force of global change, especially in its effects on sensitive freshwater ecosystems. Even protected areas are usually not immune. Ptychobarbus chungtienensis is a threatened freshwater fish now almost confined to Bita Lake, in the Shangri-La region of Yunnan province, China. Its existence is threatened by the introduction of non-native weatherfishes (Misgurnus anguillicaudatus and Paramisgurnus dabryanus) by an unusual method known as ‘prayer animal release’. Periodic surveys revealed the ratio of invasive weatherfishes to P. chungtienensis has been increasing since the former species was first recorded from the lake in August, 2009. Ptychobarbus chungtienensis shows low genetic diversity in the relict Lake Bita population. Weatherfishes, however, have highly successful survival strategies. The degree of dietary overlap between the species is alarming and perhaps critical if food is found to be a limiting factor.
Fish of the superfamily Cobitoidea sensu stricto (namely loaches) exhibit extremely high diversity of color patterns, but so far little is known about their evolutionary mechanism. Melanocortin 1 receptor gene (MC1R) plays an important role during the synthesis of melanin and formation of animal body color patterns. In this study, we amplified and sequenced the partial MC1R gene for 44 loach individuals representing 31 species of four families. Phylogenetic analyses yielded a topology congruent with previous studies using multiple nuclear loci, showing that each of the four families was monophyletic with sister relationships of Botiidae+ (Cobitidae+(Balitoridae+Nemacheilidae)). Gene evolutionary analyses indicated that MC1R in loaches was under purifying selection pressure, with various sites having different dN/dS values. Both Botiidae and Cobitidae had lower dN/dS values than those of background lineages, suggesting their evolution might be strongly affected by purifying selection pressure. For Balitoridae and Nemacheilidae, both had larger dN/dS values than those of background lineages, suggesting they had a faster evolutionary rate under more relaxed selection pressure. Consequently, we inferred that the relatively stable color patterns in Botiidae and Cobitidae might result from the strong purifying selection pressure on the MC1R gene, whereas the complicated and diverse color patterns in Balitoridae and Nemacheilidae might be associated with the relaxed selection pressure. Given the easy experimental procedure for the partial MC1R gene and its excellent performance in reconstructing phylogeny, we suggest this gene could be used as a good molecular marker for the phylogenetic study of fish species.
Triplophysa daochengensis sp. nov. is described from the Daocheng River, a northern tributary of the Jinsha River in Sichuan Province, China. The new species can be distinguished from its congeners by the following characters: body smooth and scales absent; lateral line complete; caudal peduncle compressed, depth unchanging; head length equal to caudal-peduncle length; lower jaw shovel-shaped; dorsal-fin origin anterior to pelvic-fin origin and closer to the tip of the snout than to the caudal-fin base, last unbranched ray hard; pelvic-fin tip not reaching anus; posterior chamber of gas bladder absent; intestine of spiral type with three winding coils.
In September and October 2015, a new species of the family Nemacheilidae, Triplophysa tianxingensis sp. nov., was discovered from underground water in Qiubei County, Yunnan Province, China. It can be distinguished from all other troglobiotic Triplophysa species occurring in Yunnan by the following combination of characters: eyes small, a little degenerated; barbels longer; ventral profiles greatly convex; pectoral fin short, attaining a third of the distance from the pectoral-fin base to pelvic fin base; body with many brown blotches; caudal peduncle with fin fold; caudal fin shallowly forked, and free posterior chamber of swim bladder cylindrical.
Piwi-interacting RNA (piRNA) plays an important role in the gonadal development and maintenance of Teleostei. In this study, piRNA libraries derived from the adult gonads of Japanese flounder (Paralichthys olivaceus) were generated using next-generation sequencing technology. Using zebrafish piRNAs as a reference, 5 865 unique candidate piRNAs were identified; 289 candidate piRNA clusters (PRCs) were generated from the above piRNAs. Among the isolated candidate PRCs, a total of 38 ovary-specific, 45 ovary-bias, 24 testis-specific, and 131 testis-bias PRCs were found. The relative expression levels of seven PRCs were validated through quantitative reverse transcription-polymerase chain reaction. The results of this study will help facilitate exploration of the development and maintenance of the phenotypic sex mechanism in P. olivaceus.
Sphaeroma terebrans, a wood-boring isopoda, is distributed worldwide in tropical and subtropical mangroves. The taxonomy of S. terebrans is usually based on morphological characteristics, with its molecular identification still poorly understood. The number of teeth on the uropodal exopod and the length of the propodus of the seventh pereopod are considered as the major morphological characteristics in S. terebrans, which can cause difficulty in regards to accurate identification. In this study, we identified S. terebrans via molecular and morphological data. Furthermore, the validity of the mitochondrial cytochrome c oxidase subunit I (COI) gene as a DNA barcode for the identification of genus Sphaeroma, including species S. terebrans, S. retrolaeve, and S. serratum, was examined. The mitochondrial COI gene sequences of all specimens were sequenced and analysed. The interspecific Kimura 2-parameter distances were higher than intraspecific distances and no intraspecific-interspecific distance overlaps were observed. In addition, genetic distance and nucleotide diversity (π) exhibited no differences within S. terebrans. Our results revealed that the mitochondrial COI gene can serve as a valid DNA barcode for the identification of S. terebrans. Furthermore, the number of teeth on the uropodal exopod and the length of the propodus of the seventh pereopod were found to be unreliable taxonomic characteristics for S. terebrans.
Letter to the editor