The histology of the body wall of the fish parasitic leech, Cystibranchus masstacembeli Rahemo, 1989 collected from freshwater eel, Mastacembelus simach was investigated. The body wall found consists of five layers, n...The histology of the body wall of the fish parasitic leech, Cystibranchus masstacembeli Rahemo, 1989 collected from freshwater eel, Mastacembelus simach was investigated. The body wall found consists of five layers, namely： cuticle, epidermis, dennis, muscle layer and botryoidal tissue. Cuticle is very thin layer, casting was evident in some sections, annulation was also seen in longitudinal sections, some time with sensory structures inside the crypts. Epidermis with hammer-shaped ceils, these cells are broad towards the outer and narrower towards their inner ends. In some sections intensively stained haematoxylin-eosin granules from which neck-like tubes leads with filiform projections outward to open to the exterior by minute apertures. Dermis is thicker than epidermis, with distinct large cells connected by a connective tissue and some muscle fibers, also large vacuoles or empty vesicles were detected which are haemocoelomic capillaries, which along with those situated in the epidermis make a respiratory membrane of this leech. Muscle layer consists of outer circular and inner longitudinal, the later is more abundant and occupies more space than the circular. Botryoidal tissue fills the spaces between body wall and inner intestinal or crop diverticulae, its tissue is composed of more or less rounded cells, more eosinophilic cytoplasm but with dark nuclei, intermingled with small oblique or radial muscle fibers, haemocoelomic spaces were also evident in this layer.展开更多
Growth is a polygenic trait that is under the influence of multiple physiological pathways regulating energy metabolism and muscle growth.Among the possible growth-regulating pathways in vertebrates,components of the ...Growth is a polygenic trait that is under the influence of multiple physiological pathways regulating energy metabolism and muscle growth.Among the possible growth-regulating pathways in vertebrates,components of the somatotropic axis are thought to have the greatest influence.There is growing body of literature focusing on the somatotropic axis and its role regulating growth in fish.This includes research into growth hormone,upstream hypothalamic hormones,insulin-like growth factors,and downstream signaling molecules.Many of these signals have both somatic effects stimulating the growth of tissues and metabolic effects that play a role in nutrient metabolism.Signals of other endocrine axes exhibit profound effects on the function of the somatotropic axis in vivo.In this review we highlight recent advances in our understanding of the teleost fish endocrine somatotropic axis,including emerging research using genetic modified models.These studies have revealed new aspects and challenges associated with regulation of the important steps of somatic growth.展开更多
For attaining the optimized locomotory performance of swimming fishes,both the passive visco-elastic properties of the fish body and the mechanical behavior of the active muscles should coordinate with the fish body’...For attaining the optimized locomotory performance of swimming fishes,both the passive visco-elastic properties of the fish body and the mechanical behavior of the active muscles should coordinate with the fish body’s undulatory motion pattern.However,it is difficult to directly measure the visco-elastic constitutive relation and the muscular mechanical performance in vivo.In the present paper,a new approach based on the continuous beam model for steady swimming fish is proposed to predict the fish body’s visco-elastic properties and the related muscle mechanical behavior in vivo.Given the lateral travelling-wave-like movement as the input condition,the required muscle force and the energy consumption are functions of the fish body’s visco-elastic parameters,i.e.the Young’s modulus E and the viscosity coefficient in the Kelvin model.After investigating the variations of the propagating speed of the required muscle force with the fish body’s visco-elastic parameters,we analyze the impacts of the visco-elastic properties on the energy efficiencies,including the energy utilization ratios of each element of the kinematic chain in fish swimming and the overall efficiency.Under the constraints of reasonable wave speed of muscle activation and the physiological feasibility,the optimal design of the passive visco-elastic properties can be predicted aiming at maximizing the overall efficiency.The analysis is based on the small-amplitude steady swimming of the carangiform swimmer,with typical Reynolds number varying from 2.5×104to 2.5×105,and the present results show that the non-dimensional Young’s modulus is 112±34,and the non-dimensional viscosity coefficient is 13 approximately.In the present estimated ranges,the overall efficiency of the swimming fish is insensitive to the viscosity,and its magnitude is about 0.11±0.02,in the predicted range given by previous study.展开更多
文摘The histology of the body wall of the fish parasitic leech, Cystibranchus masstacembeli Rahemo, 1989 collected from freshwater eel, Mastacembelus simach was investigated. The body wall found consists of five layers, namely： cuticle, epidermis, dennis, muscle layer and botryoidal tissue. Cuticle is very thin layer, casting was evident in some sections, annulation was also seen in longitudinal sections, some time with sensory structures inside the crypts. Epidermis with hammer-shaped ceils, these cells are broad towards the outer and narrower towards their inner ends. In some sections intensively stained haematoxylin-eosin granules from which neck-like tubes leads with filiform projections outward to open to the exterior by minute apertures. Dermis is thicker than epidermis, with distinct large cells connected by a connective tissue and some muscle fibers, also large vacuoles or empty vesicles were detected which are haemocoelomic capillaries, which along with those situated in the epidermis make a respiratory membrane of this leech. Muscle layer consists of outer circular and inner longitudinal, the later is more abundant and occupies more space than the circular. Botryoidal tissue fills the spaces between body wall and inner intestinal or crop diverticulae, its tissue is composed of more or less rounded cells, more eosinophilic cytoplasm but with dark nuclei, intermingled with small oblique or radial muscle fibers, haemocoelomic spaces were also evident in this layer.
基金supported by the National Basic Research Program of China(2010CB126302 and 2014CB138602)to Yin Zhan
文摘Growth is a polygenic trait that is under the influence of multiple physiological pathways regulating energy metabolism and muscle growth.Among the possible growth-regulating pathways in vertebrates,components of the somatotropic axis are thought to have the greatest influence.There is growing body of literature focusing on the somatotropic axis and its role regulating growth in fish.This includes research into growth hormone,upstream hypothalamic hormones,insulin-like growth factors,and downstream signaling molecules.Many of these signals have both somatic effects stimulating the growth of tissues and metabolic effects that play a role in nutrient metabolism.Signals of other endocrine axes exhibit profound effects on the function of the somatotropic axis in vivo.In this review we highlight recent advances in our understanding of the teleost fish endocrine somatotropic axis,including emerging research using genetic modified models.These studies have revealed new aspects and challenges associated with regulation of the important steps of somatic growth.
基金supported by the National Natural Science Foundation of China(Grants No.10832010)the Innovation Project of the Chinese Academy of Sciences(Grant No.KJCX2-YW-L05)
文摘For attaining the optimized locomotory performance of swimming fishes,both the passive visco-elastic properties of the fish body and the mechanical behavior of the active muscles should coordinate with the fish body’s undulatory motion pattern.However,it is difficult to directly measure the visco-elastic constitutive relation and the muscular mechanical performance in vivo.In the present paper,a new approach based on the continuous beam model for steady swimming fish is proposed to predict the fish body’s visco-elastic properties and the related muscle mechanical behavior in vivo.Given the lateral travelling-wave-like movement as the input condition,the required muscle force and the energy consumption are functions of the fish body’s visco-elastic parameters,i.e.the Young’s modulus E and the viscosity coefficient in the Kelvin model.After investigating the variations of the propagating speed of the required muscle force with the fish body’s visco-elastic parameters,we analyze the impacts of the visco-elastic properties on the energy efficiencies,including the energy utilization ratios of each element of the kinematic chain in fish swimming and the overall efficiency.Under the constraints of reasonable wave speed of muscle activation and the physiological feasibility,the optimal design of the passive visco-elastic properties can be predicted aiming at maximizing the overall efficiency.The analysis is based on the small-amplitude steady swimming of the carangiform swimmer,with typical Reynolds number varying from 2.5×104to 2.5×105,and the present results show that the non-dimensional Young’s modulus is 112±34,and the non-dimensional viscosity coefficient is 13 approximately.In the present estimated ranges,the overall efficiency of the swimming fish is insensitive to the viscosity,and its magnitude is about 0.11±0.02,in the predicted range given by previous study.
