Cavefish as biological models in the laboratory and in the wild

Cavefish have advanced to the forefront as excellent models for laboratory studies in developmental and evolutionary biology.The iconic Mexican characid,Astyanax mexicanus,which consists of a surface-dwelling morph and about 30 interfertile cave-dwelling morphs,has become a major contributor to behavior,sensory biology,trait evolution,and biomedicine(Jeffery,2020).There are about 200 scientifically-described cavefish species distributed in karst areas on most continents(Proudlove,2015).Similar to A.mexicanus,a small subset of other cavefish taxa coupled with related surface-dwelling species are now serving as additional laboratory models to address a variety of important biological problems.A prime example is the cyprinid genus Sinocycloceilus,which contains 75 closely related surface and cave species endemic to the karst massifs of southwestern China(Jiang et al.,2019,2023;Ma et al.,2019).Comparative studies of Chinese and Mexican cavefish can be used to address a host of questions concerning the convergence and divergence of cave related traits.In the future,other Chinese cavefish species,such as the cave loach,as well as the more recently discovered European cavefishes,are likely to join the current group of excellent laboratory models.This special issue of Zoological Research presents the results of current research on these diverse cavefish species.In addition to recent research using cavefish models in laboratory studies,this issue also covers new research on cavefish in the wild.

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.

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.