Now showing items 1489-1508 of 3272

    • Conference paper

      High throughput RNA sequencing reveals temperature tolerance mechanisms in Scylla serrata 

      MC Ablan-Lagman & E Meyer - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effects of increasing temperature from global climate change threaten the sustainability and production of mud crabs from farms and wild populations in mangroves. Adaptation of mud crab populations to temperature stress is difficult to evaluate until now, with the emergence of RNA-Seq, a method which evaluates total mRNA expression under different conditions. In this study, 10 individuals each of S. serrata from Buguey, Cagayan were exposed to 26~’C and 32~’C for two weeks and the mRNA profiles were compared based on 186 million high quality pair-end reads which were aligned to a S. serrata reference transcriptome assembled de novo from 24,350 contigs with an average N50 of 1564 bp. Temperature related differences in gene expression were not significantly detected between the control and treatment groups and this was mostly due to the highly expressed genes such as the low and high molecular weight heat shock proteins. However, variations were greater among genes involved in the process of cell cycle regulation, the dissimilation processes such as oxidative phosphorylation, reproduction and transport across membranes. Greater differences were observed between immature or mature males and females.
    • Article

      Histological observations on the rearing of milkfish, Chanos chanos, fry using different diets 

      H Segner & JV Juario - Journal of Applied Ichthyology, 1986 - Blackwell Publishing
      Six different diets, commonly used in the Philippines for rearing milkfish, Chanos chanos, try, were tested by means of growth, survival and histology. These diets included:

      a) live food (Artemia nauplii); b) two different dry feeds; c) natural feed supplements (rice bran, egg yolk); d) a mixture of live and dry feeds. The mixed diet was found to give the best results, closely followed by live food. The dietary value of one of both artificial feeds improved with increasing age of the fish, whereas the other was clearly inadequate. The same was true for the natural compounds. Results obtained from statistical and histological analyses were congruent; the latter provided additional insights not obtained with statistic data alone.
    • Article

      A histological study of the hypophysial-gonadal system during sexual maturation and spawning in the milkfish, Chanos chanos (Forskal) 

      JD Tan - Journal of Fish Biology, 1985 - Wiley-Blackwell
      The pituitary gland of the milkfish, Chanos chanos, was studied at different stages of sexual maturation and spawning. Consecutive median sagittal sections were treated with a range of stains to demonstrate the different cell types and regions. The milkfish pituitary consists of a neural component, the neurohypophysis, and an epithelial component, the adenohypophysis, which in turn consists of three regions: the rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). However, unlike most teleosts, the pituitary gland of the milkfish is encased in a bony chamber, has dorsal and ventral lobes and extends anteriorly from its point of origin at the base of the brain. PAS (+) basophils are found in all regions of the adenohypophysis, but mostly in the proximal pars distalis. These cells undergo hypertrophy and hyperplasia during sexual maturation, shrinkage and degranulation during spawning.
    • Book chapter

      Histology as a tool in disease diagnosis 

      ES Catap & ER Cruz-Lacierda - In GD Lio-Po & Y Inui (Eds.), Health Management in Aquaculture, 2010 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Histology is an important tool in fish disease diagnosis as it affords the comparison of normal structures or morphology of tissues against those from diseased fish. However, correct diagnosis and confirmation of changes associated with diseases require proper specimen processing and some degree of expertise in histopathology.

      The four basic types of tissues are: epithelial, connective, muscular and nervous. An organ is usually a combination of these four tissue types. It is important to remember that the histology or structure of an organ is always related to the function it performs.
    • Article

      Histopathological response of milkfish Chanos chanos Forsskal fingerlings to potassium permanganate 

      ER Cruz & CT Tamse - Fish Pathology, 1986 - Japanese Society of Fish Pathology
      Static 96 h bioassays were conducted on milkfish fingerlings at concentrations ranging from 1.00 to 1.80 mg/l KMnO4. Histopathological analyses of gills, liver, and kidney tissues revealed significant changes even in non-lethal concentrations tested. Damage became severe with increasing concentration and longer exposure to the chemical. Partial to complete recovery was observed in gills, liver, and kidney cells of fish exposed to KMnO4 for 96 h and then maintained in KMnO4-free seawater for 240 h.
    • Conference paper

      Histopathology of chlorella-feeding in larval milkfish, Chanos chanos. 

      Unicellular algae, particularly Chlorella, are widely used as starter feeds for marine finfish larvae. However, milk fish larvae when reared on Chlorella sp., suffered morality up to 100% within the first days of feeding (Fig. 1). Morality induced by Chlorella occurred earlier than that induced by starvation. The present Communication describes histopathological changes in liver and intestines of mlikfish larvae fed with Chlorella sp., copared with starvedor Artemia-fed fish. Feeding the larvea with Artemia for 7 days evofed (Ø 12-16 micro m) hepatocytes, with a well-developed and orderly arranged rough endoplasmic reticulum (rER). Greater amounts of glycogen were deposited. Whereas those fed with Chlorella (Fig. 2) resulted in cellular shrinkage (Ø 5-7micro m), complete absence of stored products, degeneration of rER. swelling of mitochondria and augmentation of lysosome-like structures (compare also Juario & Storch 1984). Starvation-related alterations of hepatocyte ultrastructure were essentially similar.

      The intestinal tract of milkfish larvae is subdivided into pharynx, esophagus, stomach, intestines I(making up to 70% of gut length), II(up to 20%), and III (up to 10%). Nutritional related changes were only observed in intestines I and II. In Artemia-fed specimens there was intensive lipid absorption in I (Fig. 3) and well-developed supranuclear vacuoles in II (Fig. 4). Under starvation, The first part of the intestine was characterized by partial cellular hydrops, autolyic vacuoles (Fig. 5) and a dissolution of basal labyrinth. The supranuclear vacuoles of II were reduced to smaller, electron dense inclusions (Fig. 6). Chlorells appeared partially digested in the gut. It evoked pathological intrcellular vacuolation of the epithelial cells and bizarre forms of the nuclei in I (Fig. 7). In II, changes were similar to starved larvae (fig. 8).

      The present report is another example of high moralities occurring among fish larvae reared on live feeds (compare Eckmann 1985).
    • Article

      Histopathology of microsporidian infection in white prawn, Penaeus merguiensis de Man, 1888. 

      MCL Baticados & GL Enriquez - Natural and Applied Science Bulletin, 1982 - University of the Philippines
      Different stages of the white prawn, Penaeus merguiensis de Man, were examined for microsporidian infection. The parasite was found only in adult female prawns exhibiting white instead of the normal olive-green ovaries. Non-germinal tissues were not infected. Spores found in the digestive tract, abdominal muscles, hepatopancreas, heart and gills were extracellular in location and did not have any histopathologic effect on these organs.
    • Article

      Histopathology of the chronic soft-shell syndrome in the tiger prawn Penaeus monodon 

      MCL Baticados, RM Coloso & RC Duremdez - Diseases of Aquatic Organisms, 1987 - Inter Research
      One of the disease problems that affect the production of tiger prawn Penaeus monodon Fabricius in brackish-water ponds is the chronic soft-shell syndrome, a condition in which the prawn shell is persistently soft for several weeks. To determine the extent of damage in affected prawns, the histopathology of this syndrome was studied using light microscopy, transmission and scanning electron microscopy, and histochemical determination of calcium. Light microscopic studies of the exoskeleton of soft and normal hard-shelled prawns showed several distinct layers: an outer epicuticle, a thick exocuticle and a thinner endocuticle overlying the epidermis. The cuticular laters of the soft shell oftern had a rough or wrinkled surface and were usually disrupted and separated from the epidermis while those of the hard shell were generally intact and attached to the epidermis. The exocuticle and endocuticle of the hard shell were considerably thicker than those of the soft shell. Ultrastructural observations revealed the presence of a very thin membranous later under the endocuticle. Tegumental ducts and pore canals traversed the 4 cuticular layers and were distinctly observed as pore openings on the epicuticle surface. The epicuticle had a bilaminar and non-lamellate structure. The exocuticle had more widely-spaced lamellae consisting of fibers arranged in a more compact pattern than in the endocuticle. Histochemical determination of calcium was done in exoskeleton and hepatopancreas of soft- and hard-shelled prawns. The hepatopancreas of soft-shelled prawn stained more intensely for calcium than that of the hard-shelled one. There was no great difference in calcium content of hard and soft shell, although the former stained slightly more intensely. Histopathological changes in the hepatopancreas of soft-shelled prawns were also observed.
    • Book chapter

      Historical and current trends in milkfish farming in the Philippines 

      T Bagarinao - In SS De Silva (Ed.), Tropical Mariculture, 1998 - Academic Press
      This chapter focuses on the historical and current practices of milkfish farming in the Philippines. The Philippines ranks among the top 12 largest fish producers in the world and the milkfish, Chanos chanos, is the official national fish. The milkfish production in the Philippines has fluctuated sharply, but on average, has relatively stagnated over the past decade, partly due to the shrimp boom and low price of milkfish. The milkfish industry has been responsible for the significant loss of valuable mangrove swamps and forests. The loss of mangrove means loss of habitats and biodiversity including nursery grounds for feeding and refuge of commercial fishes, shrimps, crabs and mollusks. Milkfish ponds in the Philippines are either privately owned or leased from the government. Brackish water fish ponds are valuable real estate and good management adds to their value. For milkfish farming, stocking rate should be based on the pond environment and carrying capacity, and the fish size at stocking and the market size desired.
    • magazineArticle

      A hito famer's success story 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1993 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Horizontal transmission of epizootic ulcerative syndrome (EUS)-associated virus in the snakehead Ophicephalus striatus under simulated natural conditions 

      GD Lio-Po, LJ Albright, GS Traxler & EM Leaño - Diseases of Aquatic Organisms, 2003 - Inter Research
      Natural transmission of the epizootic ulcerative syndrome (EUS) was conducted on naïve snakeheads Ophicephalus striatus (also known as Channa striata) kept (A) in aquifer water, (B) in lakewater, (C) cohabiting with EUS snakeheads in lakewater, and (D) cohabiting with apparently healthy snakeheads in lakewater during the 1994 to 1995 EUS season. The results showed that EUS-like lesions developed in 6 to 14 d among naïve snakeheads cohabiting with EUS snakeheads and with apparently healthy snakeheads in lakewater (Treatments C and D). Among naïve fish exposed to lakewater (Treatment B), similar lesions developed in 16 to 21 d, while naïve fish in aquifer water (Treatment A) did not develop EUS-like lesions. EUS signs began as Grade I (slight) lesions that gradually progressed to Grades III-IV (severe) 3 to 5 d from lesion onset, similar to the naturally affected EUS fish. The virus was recovered from some but not all naturally EUS-affected snakeheads, snakeheads with healing lesions and apparently healthy snakeheads, but not from naïve snakeheads. The results provide evidence of a waterborne horizontal transmission of the EUS-associated virus. This is the first report of a successful horizontal transmission of the EUSassociated virus from apparently healthy snakeheads to naïve fish under natural conditions and of virus recovery in tissue culture from naturally exposed experimental fish.
    • Article

      Hormonal changes accompanying sexual maturation in captive milkfish (Chanos chanos Forsskal) 

      CL Marte & TJ Lam - Fish Physiology and Biochemistry, 1992 - Springer Verlag
      Steroid hormone profiles accompanying sexual maturation in captive milkfish are described. There were no significant differences in levels of serum estradiol 17-β (E2) and testosterone (T) between immature male and female fish. Mean E2 levels rose from 0.54±0.11 ng/ml in immature females (Stage 1) to 4.53±1.16 ng/ml in vitellogenic females (Stage 5), while T levels increased from 2.06±0.28 ng/ml to 38.4±9.26 ng/ml. E2 and T levels were positively correlated to GSI and oocyte diameter. In males, serum T levels increased from 2.5±0.40 ng/ml in immature males to 27.73±5.02 ng/ml in spermiating males. A significantly higher T level was found in males with thick and scantly milt (spermiation index, SPI, 2) compared to males with scanty milt (SPI, 1) or males with copious, fluid milt (SPI, 3).

      Serum levels of E2 and T, and the GSI in females rose significantly during the breeding season (April–June 1983). The levels of both steroids dropped below 1 ng/ml in spent females sampled in succeeding months. In immature males, T levels ranged from 1.11 ng/ml to 2.78 ng/ml and rose significantly to 21.52±8.38 ng/ml during the breeding season when GSI peaked. Serum T levels dropped to around 10 ng/ml in the succeeding months when only spent or regressed males were sampled.
    • Conference paper

      Hormonal changes accompanying sexual maturation in milkfish Chanos chanos Forsskal 

      CL Marte & TJ Lam - In E Ohnishi, Y Nagahama & H Ishizaki (Eds.), Proceedings of the First Congress of the Asia and Oceania Society for Comparative Endocrinology (AOSCE), 4-7 November 1987, Nagoya, Japan, 1987 - Nagoya University Corporation
      In spite of the economic importance of milkfish to the Southeast Asia, relatively little information is available on its reproductive biology and physiology. Milkfish has a prolonged juvenile phase undergoes first sexual maturation at five years. Steroid hormone profiles during this juvenile phase and the change accompanying sexual maturation is described.

      There were no significant differences in levels of serum estradiol 17-B (E2), testoterone (T) and progestrone (P) of male and female immature fish. In immature fish, E2 ranfed from 0.145 to 0.600 ng/ml, T varied from 2.04 to 3.75 ng/ml, and P ranged from 0.472 to 1.16 ng/ml. Serum T, however, was significantly high in 4 years old immature fish fish while E2 was significantly high in 2 years old fish. Mean E2 level rose from 0.54 ± 0.11 ng/ml (E2) in immature female (Stage 1) to 4.53 ± 1.16 ng/ml in vitellogenic females (Stage 5) while T increased from 2.06± 0.28 ng/ml to 38.4± 9.26 ng/ml. E2 and T levels were positively correlated to egg diameter. Progesterone level, however, remained low through vitellogenesis. 17-a-OH-progesterone and 17-a, 20-B-progesterone were not detectable even in fully vitellogenic females. Gonade development in males was sccompanied by increase serum T levels only. T levels increase from 2.5± 0.40 ng/ml in immature males to 27.73± 5.02 ng/ml in spermeating males. Significantly higher T level was found in males with thick but abundant milt (spermiation index, SPI, 2+ ) compared to males with scanty milt (SPI, 1+) or mals with copious, fluid milt (SPI, 3+).

      Ther was no significant seasonal variation in levels of E2 and T of immuture 3-5 years old female sampled from july 1981 through February 19083. Serum E2 varied from 0.125 ng/ml to 1.45 ng/ml while T was uniformly low and ranged from 1.16 ng/ml tp 2.07 ng/ml. The levels of E2 and T significantly rose during the breeding season (April-June, 1983)and accompanied the increase in gonadosomatic index (GSI) aat this time (E2, 3.43± 0.49 ng/ml; T, 40.04± 16.20 ng/ml ). The levels of both steroids dropped to below 1 ng/ml in spent females sampled in the succeeding months. In immature males, mean serum E2 was beolw 1 ng/ml through except for a significan high level (2.36 ng/ml ) found in 3 years old male sampled in October to December, 1981 while T levels ranged from 1.11 ng/ml to 2.78 ng/ml. As in females, T levels significantly rose to 21.52± 8.38 ng/ml during the breding season when GSI peaked (April-June ,1983). E2 remained low throughout. T level dropped to arround 10 ng/ml in the succeeding months when spent or regressed fish were samlped
    • Conference paper

      Hormonal, environmental, and dietary manipulation of milkfish broodstock to enhance egg production 

      AC Emata - In Towards More Effective Utilization of Resources for Sustained Development. Proceedings of the First IFS-NRCP Seminar-Workshop, 26-29 April 1993, Makati, Metro Manila, Philippines, 1993 - International Foundation for Science
      The insufficient supply of milkfis fry severely limits the expanion of milkfish aquaculture. While natural spamning and hatchery production of milkfish fry have been attained recently, there is sitll a need to incease egg production from available broodstock. A number of studies geared towards this concern are currently conducted at SEAFDEC Aquaculture Department with moderate success. Chronic administration of estradiol-17B and 17A-hydroxy-progesterone to femaleand male milkfish broodstock increased maturation and rematuration rates. Milkfish kept under constant long phtoperiod (16L:8D) appeared to have prolonged gonadal development than thoes of milkfish reared under long to normal to short photoperiod. Ffrmulated diet containing 6% liquid that is feed to milkfish broodstock at a daily ration 4% of total body weight appeared sufficient for maintaning sexual maturation andspawning. Refinements in these areas canensure a better management technique that can provide maximum number of good quality eggs required by hatcheries.
    • Article

      Hormone-induced spawning and embryonic development of the rabbitfish, Siganus vermiculatus (Pisces: Siganidae) 

      EM Avila - The Philippine Scientist, 1984 - San Carlos Publications, University of San Carlos
      Induced spawning experiments were conducted on captive Siganus vermiculatus with the use of human chorionic gonadotropin (HCG APL Ayerst). The hormone was administered intramuscularly and the intraovarioan oocyte development and milt conditions of the fish were monitored by in vivo methods. Likewise, the spawning behavior and early life history of the species were observed and documented.

      Spontaneous spawnings and natural fertilization of the eggs occurred following ovulation in the fish injected with 500 IU HCG between 17 and 18 hrs after the last of a series of injections delivered at 24-hour intervals. Accelerated oocyte maturation was indicated by progressive changes in the gross morphological characters of the eggs and further thinning of milt. Dominant and aggressive behavior of the female characterized the spawning activities which commenced in the mornings.

      Newly-fertilized demersal eggs measured 0.52 ± 0.01 mm in diameter and each had a narrow perivitelline space, the yolk containing several centrally-located oil globules. Embyonic development was basically similar to that exhibited in most bony fishes. Atretic eggs retained in the body cavity averaged 0.57 ± 0.01 mm in diameter. Yolksac larvae, 1.75 ± 0.14 mm in standard length, hatched 23 to 24 hrs after fertilization in 25-25 ppt sea water at ambient temperature (25.9-28.1°C).
    • Conference paper

      Hormone-induced spawning of cultured tropical finfishes 

      CL Marte - In Advances in tropical aquaculture : workshop at Tahiti, French Polynesia, February 20-March 4, 1989, 1990 - IFREMER
      Commercially important tropical freshwater and marine finfishes are commonly spawned with pituitary homogenate, human chorionic gonadotropin (HCG) and semi-purified fish gonadotropins. These preparations are often administered in two doses, a lower priming dose followed a few hours later by a higher resolving dose. Interval between the first and second injections may vary from 3 - 24 hours depending on the species. Variable doses are used even for the same species and may be due to variable potencies of the gonadotropin preparations.

      Synthetic analogues of luteinizing hormone-releasing hormone (LHRHa) are becoming widely used for inducing ovulation and spawning in a variety of teleosts. For marine species such as milkfish, mullet, sea bass, and rabbitfish, a single LHRHa injection or pellet implant appears to be effective. Multiple spawnings of sea bass have also been obtained following a single injection or pellet implant of a high dose of LHRHa. In a number of freshwater fishes such as the cyprinids, LHRHa alone however has limited efficacy. Standardized methods using LHRHa together with the dopamine antagonists pimozide, domperidone and reserpine have been developed for various species of carps. The technique may also be applicable for spawning marine teleosts that may not respond to LHRHa alone or where a high dose of the peptide is required.

      Although natural spawning is the preferred method for breeding cultivated fish, induced spawning may be necessary to control timing and synchrony of egg production for practical reasons.
    • Book chapter

      Households, agriculture, industry, fishing, and fish farming along Imbang River, Negros Occidental 

      RC Sanares - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
      Interviews were conducted among respondents identified from the households, agriculture farms, sugar mills, and fish farms along the whole stretch of Imbang River, Malisbog River, and Muyao Creek, down to Barangay Balaring at the coast of Silay City in Negros Occidental. Among the 1,073 households, 11% used river water for washing clothes, but 20% also used the rivers for disposal of waste waters, 11% for human wastes, and 13% for animal wastes. Among the 30 respondents from the agriculture sector, 70% discharged water into the river. The two sugar mills in the area treated waste waters partially before release into the rivers; one sugar mill also released wastes in a nearby rice field. Milling wastes such as bagasse, molasses, and mud press were reused and not dumped into the river. Imbang River was both the water source and wastewater sink for seven fish farms.
    • magazineArticle

      How about [snapper] hatchery production? 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1992 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • magazineArticle

      How do mangroves cope with their environment? 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • magazineArticle

      How drugs from marine sources are isolated and produced 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The document illustrates the processes on the isolation of bioactive compounds from marine organisms and the production of marine drugs.