• Journal of fish pathology
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• v.10 no.1
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• pp.65-72
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• 1997

In the present study, acute toxicity data were obtained for hydrogen sulfide to larvae and adults of blue crab Portunus trituberculatus, white shrimp Metapenacus monoceros and prawn Macrobrachium nipponense under continuous flow through system. The larvae 96hr-$LC_{50}$ values of hydrogen sulfide were 7.3, 9.3 and $9.0{\mu}g/\ell$ for P. trituberculatus, M. monoceros and M. nipponense respectively. The larval sensitivity of the three crustaceans studied for the hydrogen sulfide was in the order of P. trituberculatus> M. nipponense> M. monoceros. The adults 96hr-$LC_{50}$ values of hydrogen sulfide were 42.5, 37.8 and $56.6{\mu}g/\ell$ for P. trituberculatus, M. monoceros and M. ripponense, respectively. The order of toxicity of hydrogen sulfide to adults of the three crustaceans was P. tritruberculatus> M. monoceros> M. nipponense. The larval/adult ratios of hydrogen sulfide toxicity were 5.8, 4.1 and 6.3 for P. trituberculatus M. monoceros and M. nipponense respectively, and larvae were found to be more sensitive to hydrogen sulfide than adults in all cases.

• Journal of Life Science
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• v.8 no.5
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• pp.582-588
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• 1998

The male reproductive system of Macrobrachium nipponense consists of a pair of lobulate testes enveloped within a mesenteric sheath extending the length of the carapace. The paired vasa deferentia originated from the mid-lateral region of each testis and extended to the genital pores at the base of the fifth walking legs. The vas deferens has four morphologically distinct regions, i.e., a short and slender proximal region, a long convoluted region, an elongate distal region and an ejaculatory duct that terminates at the genital pore. The sperm mass produced in the testes is surrounded by a basophilic matrix adjacent to the high columnar epithelium and an eosinophilic matrix adjacent to the simple columnar epithelium. The sperm cord is stored in the ejaculatory duct until it is ejaculated. Androgenic gland is found near the subterminal region of the ejaculatory duct between the muscles of the coxopodite of the last thoracic leg. The cell of the androgenic gland is about 6~8 $\mu$m in length, characterized by with extended chromatin in the large nucleus that stained weakly with hematoxylin and there is a large quantity of cytoplasm. The sperm of M. nipponense are typical of the palaemonid type, having a convex, cup shaped head and an elongated spike extending from the centre of the convex head. The spermatophore consisted of an eosinophilic matrix, a basophilic matrix and paired sperm masses which was surrounded by the basophilic matrix. It generally shows a bilaterally symmetrical structure.

• Development and Reproduction
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• v.3 no.1
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• pp.53-58
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• 1999

The androgenic gland secretes a hormone, androgenic gland hormone, which is believed to act on the differentiation of the primary, secondary, and behavioral sex characteristics in most malacostracan crustaceans. This report presents the ultrastructural morphology of the androgenic gland in the freshwater prawn Macrobrachium nipponense. This gland, located in the coxopodite of the last pair of walking legs, was attached to the subterminal region of the sperm duct. The gland was composed of simple cellular strands, encased by a fibrous sheath. Microvilli were situated in the fibrous sheath, especially at the edge of each cellular strand. The androgenic gland cells had the large and round nucleus and rough endoplasmic reticulum arranged either in spirals or in concentric circles throughout the cytoplasm of the cell. They also had the well-developed Golgi complex and long mitochondria with flat and transverse cristae. The Golgi complex was similar to microvesicular cluster, but usually in the shape of typical dictyosomes, These features of androgenic gland cells coincides well with the protein/peptide secretion in their function. However, despite the apparent ultastructual equipment for protein/peptide secretion, no accumulation of materials secreted were noticed in the cytoplasm. Therefore it is strongly suggested that the transient transportation of the materials into the hemocoel has occurred just after synthesis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.237-246
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• 1995

Larvae of the freshwater shrimp, Macrobrachium nipponense were reared in the laboratory at constant condition $(25^{\circ}C,\;7\%o)$, and their feeding rate, oxygen consumption rate, and growth rate were measured in regular intervals of time during larval development. Regression equations describing rates of feeding, growth and respiration as functions of time during individual larval molt cycles were inserted in a simulation model in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Absolute values for feeding, growth, respiration and assimilation showed clear changes during the molt cycle, The absolute and specific values of respiration (R: R/C) showed small variation during the individual molt cycles. Significance of respiration in relation to growth (G) increased within the carbon budget, respiration rate (R/C) outbalanced growth rate (G/C) in late premolt. When the portion of metabolizable carbon is respired (R/G), metabolic coefficient was < 1 (i.e. R$(K_2)$ decreased concurrently, In cumulative carbon budget, total feeding was $491.54\;{\mu}g$ C/ind., assimilation was $85.3\%$, respiration was $47.7\%$, and growth was $37.6\%$ from hatching to postlarval stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.380-389
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• 1994

Larvae of the freshwater shrimp, Macrobrachium nipponense(De Haan) were reared in the laboratory under constant conditions ($25^{\circ}C,\;7\%0$ S), and their feeding rate, oxygen consumption, ammonia nitrogen excretion, and growth were measured at regular intervals during development from hatching to post larval stage. Growth was measured as dry weight, carbon, nitrogen, hydrogen, protein and lipid. All these physiological and biochemical traits revealed significant changes from instar to instar. Average feeding rate was high in intermolt stage of the molt cycle and it showed a bell-shaped pattern. Respiration(R) increased from hatching to post larval stage. Excretion(U) increased in intermolt phase of larvae and it showed a bell-shaped variation pattern, in all larval instars with a maximum near the middle of the molt cycle. Regression equations describing rates of feeding, growth, respiration and ammonia excretion as functions of time during individual larval molt cycles were inserted in a simulation model, in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Carbon was initially increased and nitrogen showed a tendency to increase in premolt phase during individual molt cycles. Protein remained clearly the predominant biochemical constituent in larval biomass.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.403-407
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• 2000

Ultrastructure and function of testis somatic cells in freshwater prawns Macrobrachium nipponense were studied. The paired testes of the prawn were elongated, united at their anterior end, which lay between the dorsal surface of the hepatopancreas and the heart. Each testis consisted of a large number of seminiferous cords compactly held together by connective tissue. A seminiferous cord was composed of an outer layer of simple squamous epithelium, a basement membrane, the closely packed germ cells and sustentacular cells of the germinal ridge, and an inner layer of simple cuboidal epithelial cells. Leydig cell-like cells in an angular areas filling the space of the seminiferous cords were observed. The nuclei of leydig cell-like cells were characterized by a distinct nucleolus. The simple squamous epithelial layer was composed of flattened cells tying on a basement membrane. The nuclei of the flattened cells were often overlapped in a layer, and the cytoplasm of the cells was observed just near the nuclei. The sustentacular cells were complex in morphology. These cells had relatively small cell bodies from which long cytoplasmic extensions ramified reached the space of germ cells in the germinal ridge. The nuclei of sustentacular cells usually exhibited angular profiles and located most commonly at the periphery of the cords. Cells of simple cuboidal epithelium located between germinal ridge and lumen of seminiferous cord, and part of the cells were adjacent to basal lamina, The cuboidal epithelial cells contained numerous mitochondria, the well-developed rER, the well-developed Golgi complex, and irregularly shaped nuclei. Transition vesicles appeared on the cis side of the Golgi complex. The large vesicles on the trans side of the complex appeared to fuse to form a membrane-bound structure. A number of pits on the cell apex suggested exocytotic activity for secretion of the sperm supporting matrix.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.253-258
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• 2002

The androgenic gland secretes a hormone, androgenic gland hormone, which is believed to act on the differentiation of the primary, secondary, and behavioral sex characteristics in most malacostracan crustaceans. Based on the changes in gonado-somatic indexe and histological observation of testis and androgenic gland cell, testicular maturation and spermatogenesis of M. nipponense occurred early in summer (May to July), and generally spermatogenesis was absent in August. It could be, concluded that May to July is the period when adult males of this species are sexually active, and androgenic gland showed signs of increased secretory activity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.424-430
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• 2002

Vas deferens is a long tube and could be divided into four regions as its morphological characters: a short and slender proximal region, a convoluted region, a straight and more thick distal region, and an ejaculatory duct, It is connected with the posterior outer horns of the testis and runs to the gonopores opened on the coxa of the fifth walking legs, The proximal region consists almost entirely of simple cuboidal epithelial cells, $12\~28{\mu}$m in height, surrounded by a thin basal membrane. A small aggregation of high cuboidal epithelium is obsened from one side of the proximal region. The convoluted and distal region is composed of two kinds of epithelial cells; high cuboidal epithelial cells, $40\~120{\mu}m$ in height located in dorsal portion and simple cuboidal epithelial cells of $12\~28{\mu}$m in height located in ventral and lateral portion. The ejaculatory duct is surrounded with two kinds of muscle layers, inner longitudinal and outer circular muscle fibers, The lumen is lined with high and simple cuboidal epithelium in almost equal proportions. The proximal region contains mature sperm and basophilic substances. The eosinophilic substances appeared newly going toward the convoluted region and are laid along simple cuboidal epithelial cell layer. Tube-like content (spermatophore) of the vas deferens is ejaculated from a pair of genital pores at mating. Two masses of the content fuse together side by side and are usually deposited on the female thorax between the second and fourth or fifth pereiopods, The spermatophore formed measures $2.7\~4.0$ mm in length and $1.5\~2.7$ mm in width.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.270-271
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• 2000

십각 갑각류의 수정관은 정자의 성숙, 정포형성에 관여하는 물질의 획득 그리고 교미 전까지 정포를 저장하는 역할을 하며, 종에 따라 수정관은 3에서 10개의 부분으로 나뉘어지며, 부위에 따라 그 기능이 다른 것으로 알려져 있다 (Mclaughlin, 1983; Hinch and McKnight, 1988; El-Sherief, 1991). 본 종은 체장 90mm 전후까지 성장하며, 우리 나라 담수산 새우류 중에서는 비교적 대형종에 속한다. (중략)

• Journal of Aquaculture
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• v.4 no.1
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• pp.31-66
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• 1991

This paper deals with the reproductive ecology e.g., number of the pre-spawning moults, morphological characteristics of the pre-spawning moult the common moult, daily ration druing a molting cycle mating behavior, structures of spermatozoa and spermatophore, structure of vas deferens, mechanisms of the oviposition and brooding into the egg-chambers, a suitable time for the artificial mating and fertilization, time sequence of the oviposition and brooding into egg-chambers from the copulation, responses to temperature and chlorinity on the egg development and hatching, effect of temperatures on duration of egg development, physical mechanism of the egg hatching, to make an attempt for the artificial spawning and brooding to establish a suitable system of the artificial seedling-production for the aquaculture. 1. Females molted commonly $8{\~}10$ times at an interval of $17{\~}18$ days at $28^{\circ}C,\;3.26\~4.35\%_{\circ}$ while the prespawning moltings were $4{\~}5$ times at an interval of $13{\~}14$ days. The suitable state for artificial copulation was within 14 hours elapsed from the prespawning moltings (most suitable state was within 8 hours). Males discharged a gelatinous spermatophore and placed it on the females sternum during copulation. Oviposition was seen $6{\~}17$ hours after copulation. External fertilization was considered to take place at oviposition. Fertilized eggs held in egg-chambers forming between pleopods were about $5000{\~}6000$ in females those sizes about 6.5 cm in body length. 2. Eggs immediately after oviposition were elliptic shape, measuring $0.58{\times}0.48$ mm up to hatching. Their sizes increased with egg development and finally reached $0.85{\times}0.54$ mm up to hatching. The relationship between the long axis of the egg(Y in U) and days elapsed(X) was expressed as Y= 5.60194 + 0.007358X. The eggs performed superficial cleavage and their cleavage furrows became visible at the 4-daughter-nucleus stage. The eggs showed normal development up to hatching at water temperature range of $22{\~}30^{\circ}C$ (optimum temperature : $26{\~}28^{\circ}C$) and at chlorinity range of $0.00\~6.64\%_{\circ}$ (optimun chlorinity : $2.21{\%}_{\circ}$). The relationship between incubation period (Y in days) and water temperature(X in $^{\circ}C$) could be expressed as Y= 50.803-1.3555X. The eggs hatched $12{\~}13$ days after oviposition at $28.0{\~}28.6^{\circ}C$ 3. The pre-spawning moltings were appreciably different in the morphologic structure from those of common moltings. Breeding setae and dresses were formed on the thoracic regions, abdominal epimerae and the bases of the first to fourth pleopods in order to prepare and support oviposition, transfering and supporting eggs in egg-chambers up to hatching. These supplementary breeding organs were observed only at reproductive seasons.