Sinocyclocheilus sanxiaensis, a new blind fish from the Three Gorges of Yangtze River provides insights into speciation of Chinese cavefish

DEAR EDITOR,A blind fish of Sinocyclocheilus (Cypriniformes: Cyprinidae)was caught in open water in the Three Gorges (Sanxia)reservoir, at a depth of 20 m in the mainstream of YangtzeRiver in Zigui County, Hubei Province, China. This fish can beeasily distinguished from all other congeners by externalmorphological characteristics, and is estimated to havediverged from its sister group about 0.55 million years ago(Ma). The geologically well separated locality of this specieshas expanded the distribution of Sinocyclocheilus cavefishfrom around N25°(latitude) to above N30°. Herein, wedescribe this new species as Sinocyclocheilus sanxiaensis sp.nov., and discuss the possible reasons why the speciesappears, surprisingly, in the Three Gorges reservoir.

Vicariance and monsoon as drivers of diversification of nemacheilid loaches(Teleostei:Cypriniformes)around the Hengduan Mountains of China

DEAR EDITOR,High mountainous terrains facilitate the diversification of biota by providing a variety of opportunities for isolation(Favre et al.,2015).Within the Nemacheilidae family of loaches,the highly diverse Nemacheilini tribe is a polyphyletic group,with extensive distribution across the Indian and Eurasian plates(Chen et al.,2019;Sgouros et al.,2019).

Comparative analysis and phylogenetic and evolutionary implications of mitogenomes of Chinese Sinocyclocheilus cavefish(Cypriniformes:Cyprinidae)

DEAR EDITOR,Cavefish are of considerable interest due to the remarkable morphological changes that occurred during their adaptation to cave or subterranean river habitats.These changes are thought to involve trade-offs in metabolic requirements and energy utilization.Mitochondria play a vital role in oxygen use and energy metabolism;thus,mitochondrial genes are likely to have experienced specific selective pressures during cavefish evolution.In this study,we assembled and annotated the mitogenome of Sinocyclocheilus sanxiaensis,a typical cavefish species in China.Using this sequence and other available mitogenomes from the NCBI database,we reconstructed an updated phylogeny of Sinocyclocheilus based on 29 species.Five species groups were revealed,with the recently erected S.microphthalmus species group supported.To determine whether divergent selective pressures have acted on the protein-coding genes(PCGs)of the 29 Sinocyclocheilus species exhibiting different morphological features(including eye shape and body color),the fish were classified into three groups according to their cave-related traits.The branch model test revealed higher nonsynonymous/synonymous substitution ratios(ω)in the cave-dwelling groups,potentially resulting from a balance between adaptive selection and relaxed functional constraints.Sophisticated analysis using site and branch-site models identified 24 highly credible positive selection sites located on nine PCGs,with most sites also showing radical changes in amino acid properties.This study sheds light on the phylogeny and mitogenomic evolution of Sinocyclocheilus cavefish,highlighting their successful adaptation and survival in subterranean environments.

Protection and exploration of the scientific potential of Chinese cavefish

The karst habitats of Southwest China contain the richest cavefish fauna in the world.However,many Chinese cavefish species are now at high risk of extinction.Chinese cavefish have evolved unusual traits,which are important for studying adaptive evolution and modeling human diseases.Here,we call on scientific research institutions to develop programs to conserve precious cavefish species and suggest international cooperation to promote research on cavefish in China.

黑颈鹤春秋季和日间迁徙行为策略:时机和进程

2006年10月29日—2007年5月19日,于云南省大山包黑颈鹤国家级自然保护区对黑颈鹤(Grus nigricollis)越冬种群的春秋季和春季日间迁徙行为进行研究。结果表明:越冬的黑颈鹤种群稳定期为947只,最高1199只,90%个体的越冬时长为153天,最长为203天。越冬期间黑颈鹤种群数量呈现春秋迁徙期间的高峰期,说明大山包为黑颈鹤迁徙的中途停歇地和集散地。春季迁徙期间,黑颈鹤主要集成大于20只的群体(45.83%)于晴朗、轻风的天气开始迁徙,94.7%的个体于每日13:00之前开始迁徙,10:00—11:00为每日的迁徙高峰时段。春季迁徙期,随温度上升每日迁徙的黑颈鹤比例上升(r=0.709),迁徙群体也呈增大趋势(r=1.000),并且起始迁徙时间显著提前(r=–1.000)。随着日期的推移黑颈鹤每日迁徙的比例显著升高(r=0.854,n=6,P=0.031),表明黑颈鹤迁徙具有自我催促机制,而迁徙过程受到强风和多云天气的负影响。

胰十二指肠切除术后胰瘘的相关危险因素及预防措施的最新进展

术后胰瘘(postoperative pancreatic fistula,POPF)是胰十二指肠切除术(pancreatoduodenectomy,PD)后最严重的并发症,可导致患者术后恢复缓慢、病情恶化甚至再次手术及死亡.目前PD后死亡率已较前下降,但POPF的发生率仍较高,因此,探讨影响胰瘘发生的危险因素及预防策略成为胰腺外科的研究热点.文章就POPF的本质、危险因素以及预防措施进行综述.

A review of the Cypriniform tribe Yunnanilini Prokofiev,2010 from China,with an emphasis on five genera based on morphologies and complete mitochondrial genomes of some species

The loach tribe Yunnanilini from China is reviewed here using morphological characters and complete mitochondrial genomes of select species.Molecular data suggest that the tribe Yunnanilini is not monophyletic and can be divided into three clades.Species of the Yunnanilus nigromaculatus group form an independent genus and are placed in Eonemachilus.In the phylogenetic tree,Y.jinxiensis clusters with Paranemachilus genilepis,and Y.pulcherrimus clusters with Micronemacheilus cruciatus,indicating that Y.jinxiensis and Y.pulcherrimus belong to Paranemachilus and Micronemacheilus,respectively.Based on while Y.jinxiensis and Y.pulcherrimus,are placed in Paranemachilus and Micronemacheilus,respectively.Yunnanilus niulanensis and Y.qujinensis are treated as junior synonyms of Eonemachilus caohaiensis.Eonemachilus,Micronemacheilus,and Yunnanilus are show short separation between anterior and posterior nostrils.The genera can be distinguished from each other by mouth structure,lateral line and cephalic lateral-line canals,and papillae on median part of both lips.The anterior and posterior nostrils of Heminoemacheilus and Paranemachilus are closely set.Paranemachilus and Micronemacheilus are distinguished by cheeks covered with scales and lips with papillae,respectively.Our phylogenetic tree and morphological characters support Traccatichthys as a valid genus,which can be distinguished from Micronemacheilus by anterior and posterior nostrils closely set(vs.clearly separated).Four species are placed in Traccatichthys.

Morphological analysis of the Chinese Cipangopaludina species(Gastropoda; Caenogastropoda: Viviparidae)

Viviparidae are widely distributed around the globe, but there are considerable gaps in the taxonomic record. To date, 18 species of the viviparid genus Cipangopaludina have been recorded in China, but there is substantial disagreement on the validity of this taxonomy. In this study, we described the shell and internal traits of these species to better discuss the validity of related species. We found that C. ampulliformis is synonym of C. lecythis, and C. wingatei is synonym of C. chinensis, while C. ampullacea and C. fluminalis are subspecies of C. lecythis and C. chinensis, respectively. C. dianchiensis should be paled in the genus Margarya, while C. menglaensis and C. yunnanensis belong to genus Mekongia. Totally, this leaves 11 species and 2 subspecies recorded in China. Based on whether these specimens' spiral whorl depth was longer than aperture depth, these species or subspecies can be further divided into two groups, viz. chinensis group and cathayensis group, which can be determined from one another via the ratio of spiral depth and aperture depth, vas deferens and number of secondary branches of vas deferens. Additionally, Principal Component Analysis indicated that body whorl depth, shell width, aperture width and aperture length were main variables during species of Cipangopaludina. A key to all valid Chinese Cipangopaludina species were given.

Three-dimensional morphology of the Sinocyclocheilus hyalinus(Cypriniformes: Cyprinidae) horn based on synchrotron X-ray microtomography

Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China. Several species possess a conspicuous horn on their head, which has been suggested as a constructive troglomorphic trait but lacks substantial evidence. We used noninvasive, high spatial resolution synchrotron X-ray microtomography to investigate the three-dimensional(3D) morphology of the horn of Sinocyclocheilus hyalinus, one of eight such troglobiotic species. 3D renderings demonstrated the osteological components,which were comprised of a rear wall comprised of the supraoccipital bone, a remaining frontal wall with numerous fenestrae, and the bottom continuous with the parietal and epiotic. A horn cavity occurred within the horn. The fenestrae in the frontal wall were continuous in the horn cavity and showed elaborate channeling, and were, connected to the cranial cavity by soft tissue. We tentatively called this configuration the "otocornual connection" due to its anatomic and putative functional similarity to the otolateralic connection in clupeids and loricariids, which provide an indirect pathway to enhance perception of underwater sound signals. This study provides a functional morphology context for further histological and physiological investigations of such horn structures in Sinocyclocheilus cavefish, and we suggest that the horn might enhance acoustic perception to compensate for visual loss in subterranean life, which warrants future physiological examination as lab-reared S. hyalinus become available.

Molecular mechanisms of intermuscular bone development in fish:a review

Intermuscular bones(IBs)are slender linear bones embedded in muscle,which ossify from tendons through a process of intramembranous ossification,and only exist in basal teleosts.IBs are essential for fish swimming,but they present a choking risk during human consumption,especially in children,which can lead to commercial risks that have a negative impact on the aquaculture of these fish.In this review,we discuss the morphogenesis and functions of IBs,including their underlying molecular mechanisms,as well as the advantages and disadvantages of different methods for IB studies and techniques for breeding and generating IB-free fish lines.This review reveals that the many key genes involved in tendon development,osteoblast differentiation,and bone formation,e.g.,scxa,msxC,sost,twist,bmps,and osterix,also play roles in IB development.Thus,this paper provides useful information for the breeding of new fish strains without IBs via genome editing and artificial selection.

Morphological and molecular studies on Garra imberba and its related species in China

Garra imberba is widely distributed in China. At the moment, both Garra yiliangensis and G. hainanensis are treated as valid species, but they were initially named as a subspecies of G. pingi, a junior synonym of G. imberba. Garra alticorpora and G. nujiangensis also have similar morphological characters to G. imberba, but the taxonomic statuses and phylogenetic relationships of these species with G. imberba remains uncertain. In this study, 128 samples from the Jinshajiang, Red, Nanpanjiang, Lancangjiang, Nujiang Rivers as well as Hainan Island were measured while 1 mitochondrial gene and 1 nuclear intron of 24 samples were sequenced to explore the phylogenetic relationship of these five species. The results showed that G. hainanensis, G. yiliangensis, G. alticorpora and G. imberba are the same species with G. imberba being the valid species name, while G. nujiangensis is a valid species in and of itself.

Effects of osmotic pressure, temperature and stocking density on survival and sexual reproduction of Craspedacusta sowerbii

The effects of osmotic pressure, temperature and stocking density on medusae survival of Craspedacusta sowerbii were examined. The medusae were shown to be sensitive to the variations of osmotic pressure. And the survival time was <90 h at 34 m Osm/L and it declined rapidly with rising osmotic pressure. The peak survival time of >200 h was recorded at 0.2 m Osm/L. Comparing with 27 °C and 32 °C treatments, 23 °C treatment yielded lower activities at a range of 8-13/min. However, there was a longer survival time. A non-linear relationship existed between survival time and stocking density. Lower density resulted in larger body size. And sexual reproduction resumed after breeding for >22 days. Newly-formed polyps and medusae appeared subsequently but only in the higher-density groups of 10, 14 and 18 ind./L. It suggested that the number of newly-formed polyps and medusae was highly dependent on stocking density. That is, a higher stocking density produced more organisms. However, newly-formed medusae died within one month and none grew a diameter of >5 mm.

What is the destiny of a threatened fish, Ptychobarbus chungtienensis, now that non-native weatherfishes have been introduced into Bita Lake, Shangri-La？

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.

Three-dimensional morphology of the Sinocyclocheilus hyalinus(Cypriniformes:Cyprinidae)horn based on synchrotron X-ray microtomography

Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China.Several species possess a conspicuous horn on their head,which has been suggested as a constructive troglomorphic trait but lacks substantial evidence.We used non-invasive,high spatial resolution synchrotron X-ray microtomography to investigate the three-dimensional(3D)morphology of the horn of Sinocyclocheilus hyalinus,one of eight such troglobiotic species.3D renderings demonstrated the osteological components,which were comprised of a rear wall comprised of the supraoccipital bone,a remaining frontal wall with numerous fenestrae,and the bottom continuous with the parietal and epiotic.A horn cavity occurred within the horn.The fenestrae in the frontal wall were continuous in the horn cavity and showed elaborate channeling,and were,connected to the cranial cavity by soft tissue.We tentatively called this configuration the“otocornual connection”due to its anatomic and putative functional similarity to the otolateralic connection in clupeids and loricariids,which provide an indirect pathway to enhance perception of underwater sound signals.This study provides a functional morphology context for further histological and physiological investigations of such horn structures in Sinocyclocheilus cavefish,and we suggest that the horn might enhance acoustic perception to compensate for visual loss in subterranean life,which warrants future physiological examination as lab-reared S.hyalinus become available.

Systematic relationships of Chinese freshwater semisulcospirids (Gastropoda, Cerithioidea) revealed by mitochondrial sequences

The systematics of Semisulcospiridae in China is revised here based on morphological characters and mitochondrial phylogenetics. Phylogenetic relationships within the Chinese semisulcospirids were assessed via DNA sequences from mitochondrial analysis (cytochrome c oxidase I and 16S rRNA). This research contains most morphospecies of semisulcospirids previously recorded in China. Based on these results, the family of Chinese Semisulcospiridae is represented by three genera: i.e., viviparous Semisulcospira B?ttger, 1886, oviparous Hua Chen, 1943 and Koreoleptoxis Burch and Jung, 1988. These genera can be distinguished from each other by reproductive anatomy, reproductive mode, and radula features. Species of Hua are mainly distributed in southwest China and Guangxi, whereas Koreoleptoxis and Semisulcospira are mainly distributed in south and northeast China.

Construction of a chromosome-level genome assembly for genome-wide identification of growth-related quantitative trait loci in Sinocyclocheilus grahami(Cypriniformes,Cyprinidae)

The Dianchi golden-line barbel,Sinocyclocheilus grahami(Regan,1904),is one of the“Four Famous Fishes”of Yunnan Province,China.Given its economic value,this species has been artificially bred successfully since 2007,with a nationally selected breed(“S.grahami,Bayou No.1”)certified in 2018.For the future utilization of this species,its growth rate,disease resistance,and wild adaptability need to be improved,which could be achieved with the help of molecular markerassisted selection(MAS).In the current study,we constructed the first chromosome-level genome of S.grahami,assembled 48 pseudo-chromosomes,and obtained a genome size of 1.49 Gb.We also performed QTL-seq analysis of S.grahami using the highest and lowest bulks(i.e.,largest and smallest size)in both a sibling and random population.We screened two quantitative trait loci(QTLs)(Chr3,14.9-39.1 Mb and Chr17,4.1-27.4 Mb)as major growth-related locations.Several candidate genes(e.g.,map2k5,stat1,phf21a,sox6,and smad6)were also identified,with functions related to growth,such as cell differentiation,neuronal development,skeletal muscle development,chondrogenesis,and immunity.These results built a solid foundation for in-depth MAS studies on the growth traits of S.grahami.

Restocking of Anabarilius grahami in Lake Fuxian,Southwest China:morphological and genetic effects

DEAR EDITOR,The restocking of the endangered Kanglang white minnow(Anabarilius grahami)in Lake Fuxian,China,has been conducted for 13 years.However,few studies have reported on the effectiveness of the captive breeding and release of this species.

From mainland to islands:colonization history in the tree frog Kurixalus(Anura:Rhacophoridae)

The origin and colonization history of Kurixalus,a genus of small arboreal tree frogs breeding exclusively in shallow swamps,is under disputed.On the basis of comprehensive sampling program,the evolutionary history of Kurixalus is investigated based on 3 mitochondrial genes.Our results indicate that the genus Kurixalus originated in the Asian mainland and subsequently arrived at its current distribution in Borneo,Taiwan,Ryukyu,and Hainan islands by a series of dispersal events.Moreover,the colonization of Taiwan from mainland Asia has occurred 2 times.The initial colonization of Taiwan occurred at 3.46-8.68 Mya(95%highest posterior density),which rejects the hypothesis that Kurixalus probably originated from Taiwan during the early Oligocene and favors the model of Neogene-origin rather than the model of Quaternary-origin for Taiwan Residents Kurixalus.Kurixalus eiffingeri has dispersed from Taiwan to the Ryukyus once or 2 times pending more data.Both transoceanic dispersal and landbridge dispersal have played a role in the colonization process;the former resulted in the colonization of Taiwan and the Ryukyus and the latter led to the colonizati on of Bor neo and Hain an.