Phosphorus retention efficiency in rainbow trout fed diets with low fish meal and alternative protein ingredients

ABSTRACT:   Two experiments were conducted to evaluate feed quality and body phosphorus (P) and nitrogen (N) retention by rainbow trout fed test diets with low amounts of fish meal content and alternative low-P protein sources. A fish meal (FM) diet was used as control. Fish weighing 2.0 g and 134.7 g on average were reared with the experimental diets for 30 weeks and 15 weeks, respectively. The experimental diets had a good growth rate and feed utilization. In the first experiment the P retention was higher in the group of fish fed test diets (56 and 69%) compared to the FM-based diet (36%); N retention rates were similar for all groups. In the second experiment, fish were fed the test diet that had the best P retention in the earlier experiment. The P retention was lower than the values obtained in the first experiment (smaller fish), but still higher in the group of fish fed the low FM diet in comparison with the control group (36.0% and 22.2%, respectively). This represents a P loading into the water of 5.9 kg/t and 12.8 kg/t production for the test and the control diet, respectively. Therefore, low-P-loading diets for rainbow trout can be developed through the appropriate combination of alternative protein sources.     

Taste-active components in a Vietnamese fish sauce

Taste-active components were determined for a typical first-grade Vietnamese fish sauce Nuoc mam , of which total content of extractive compounds reached as high as 20 g/ 100 mL. A complete synthetic extract prepared from 35 compounds according to the analytical data reproduced almost satisfactorily the taste of the original fish sauce. From the synthetic extract, 11 compounds were identified to be the taste-active components by a series of omission and addition tests. The components consisted of glutamic and aspartic acids, threonine, alanine, valine, histidine, proline, tyrosine, cystine, methionine, and pyroglutamic acid. The most effective compound for recreating the characteristic flavor of fish sauce was glutamic acid, followed by pyroglutamic acid and alanine. Many of these components contribute to umami, sweetness, and overall taste of fish sauce. Even though the simplified 11-component extract reproduced the taste of fish sauce, the taste strength was weaker than that of the complete synthetic extract or fish sauce itself.     

Morphological analysis of cell distribution and network structure via gap junctions in swine corneal stroma

Because of corneal transplantation limitations, there is a need for cornea-specific regenerative medicine. The development of such regenerative medicine has been delayed because of the complex and unique structure of the corneal stroma. Few studies have explored the corneal stroma cell distribution and cell types in vivo. This study investigated regional differences in morphological characteristics and distributions of corneal keratocytes and immunocompetent cells in the corneal stroma to clarify their functions and structural characteristics. The porcine eyeballs were subjected to light microscopy, transmission electron microscopy, scanning electron microscopy, and immunofluorescence staining analyses. Corneal cells were primarily located in the limbus, rather than the center of the cornea; the long keratocyte diameter was largest on the epithelial side of the corneal limbus, while the short diameter was largest on the endothelial side of the central cornea. Moreover, there were significantly more corneal cells on the epithelial side than on the endothelial side in both the central and limbus areas. Gap junctions between cells in the corneal stroma were present on the surfaces of cytoplasmic processes. Many cytoplasmic processes were scattered throughout the corneal stroma; they were connected both vertically and horizontally, forming an intercellular network. Additionally, immunocompetent cells on the epithelial side suggested to participate in this network via gap junctions. The morphology of keratocytes and immunocompetent cells on the epithelial side suggests that they play important roles in corneal homeostasis.     

Experimental approach to prezygotic chromosome screening using only a single pair of gametes in mice

During in vitro embryo production, chromosome screening is essential to prevent pregnancy losses caused by embryonic chromosome aberrations. When the chromosome screening is completed before fertilization, gametes are effectively utilized as genetic resources. The aim of this study was to investigate whether chromosome screening of gametes accompanied by fertilization would be feasible using a single mouse spermatozoon and oocyte. Metaphase II oocytes were divided into a cytoplast and a karyoplast. For genome cloning of the gametes, androgenic and gynogenic embryos were produced by microinjection of sperm into cytoplasts and parthenogenetic activation of karyoplasts, respectively. Pairs of blastomeres from androgenic and gynogenic embryos were fused electrically to produce diploid embryos, which were transferred into pseudopregnant surrogate mothers to examine fetal development. Blastomeres from androgenic and gynogenic embryos were individually treated with calyculin A—a specific inhibitor of type 1 and 2A protein phosphatases—for 2 h to induce premature chromosome condensation. Thereafter, chromosome analysis of blastomeres, reflecting the genetic constitution of individual spermatozoa and oocytes, was performed, and we confirmed that most of the androgenic and gynogenic 2-cell embryos had a haploid set of chromosomes in their sister blastomeres. The reconstructed embryos from blastomeres of androgenic and gynogenic 2-cell embryos could be implanted and develop into live fetuses, albeit at low efficiency. This study indicates that prezygotic chromosome screening and embryo production using a single pair of gametes may be practicable.     

Differential expression of myostatin and its receptor in the porcine anterior pituitary gland

Myostatin (MSTN), known as growth and differentiation factor 8 (GDF-8), is a member of the transforming growth factor β (TGF-β) superfamily that negatively regulates skeletal muscle mass. Myostatin binds with high affinity to the receptor serine threonine kinase activin receptor type IIB (ActRIIB). Activins that also belong to the TGF-β superfamily, stimulate follicle-stimulating hormone production in gonadotrophs and suppress growth hormone and adrenocorticotropic hormone production in somatotrophs and corticotrophs, respectively. The aim of the present paper was therefore to clarify the endocrine action of MSTN in adenohypophysis. The present study details the expression and cellular localization of MSTN and ActRIIB in porcine anterior pituitary gland. The mRNA of MSTN and ActRIIB was consistently expressed in RT-PCR. Immunohistochemistry of MSTN and specific hormones showed that MSTN localized in thyrotrophs and gonadotrophs, in which most of the MSTN immunoreactive cells were identified as thyrotrophs. The immunostaining of ActRIIB was restricted to corticotrophs. These results indicate that MSTN was mainly produced in thyrotrophs and its receptor, ActRIIB, was restrictively contained in corticotrophs. Interestingly, thyrotrophs immunoreactive for MSTN were frequently close to corticotrophs immunoreactive for ActRIIB. The present study suggests that MSTN from thyrotrophs may regulate corticotroph function as a paracrine mediator among the porcine anterior pituitary cells.     

Effects of Thiopental, Ketamine, Diazepam, Xylazine, and Nitrous Oxide on EEG Spike Activity and Convulsive Bfehavior During Enflurane Anesthesia in Spontaneously Breathing Atropinized Cats Effect at Surgical Depth

The effects of thiopental, ketamine, diazepam, xylazine and nitrous oxide, and combinations of thiopental-nitrous oxide and ketamine-nitrous oxide on electroencephalographic (EEG) spike activity and convulsive behaviors in atropinized cats at surgical depth of enflurane anesthesia were assessed quantitatively for 60 minutes during spontaneous ventilation. Mean inspired enflurane concentrations (MIEC) were reduced 16% to 29% by pretreatment with thiopental, ketamine, diazepam, and xylazine, and were reduced 19% by 66% nitrous oxide. The MIEC of cats anesthetized with thiopental-nitrous oxide-enflurane and ketamine-nitrous oxide-enflurane were 35% to 38% lower than that with nitrous oxide-enflurane. Pretreatment with thiopental, ketamine, diazepam, and xylazine did not reduce the EEG spike frequency during anesthesia but did markedly reduce the spike amplitude. The addition of 66% nitrous oxide did not alter the spike frequency during anesthesia but tended to reduce the spike amplitude. Combinations of thiopental-nitrous oxide and ketamine-nitrous oxide almost abolished the spike activity. The addition of 66% nitrous oxide prevented convulsive responses elicited by photic and auditory stimulation during enflurane anesthesia. Treatment with thiopental, ketamine, diazepam and xylazine, and combinations of thiopental-nitrous oxide and ketamine-nitrous oxide, completely prevented convulsive responses during enflurane anesthesia.     

Balancing protein ingredients in carp feeds to limit dischargeof phosphorus and nitrogen into water bodies

ABSTRACT:   Through a series of experiments, it has been demonstrated successfullythat an appropriate choice of ingredients is primary for achievinga reduction in phosphorus (P) and nitrogen (N) loading from carpculture. In this final study, four multi-ingredient diets were examined.In addition to the basal ingredients (fish meal 15%, corngluten meal 8%, defatted soybean meal 10%, blood meal3–5%), three of the test diets (PF, MM, and SP)contained 6% each of either poultry feather meal, meatmeal or soy protein concentrate, respectively, and the fourth diet(PMS) had each of the three aforementioned ingredients includedat 3%. These diets had crude protein < 35%,digestible energy > 3.5 kcal/g,available P between 0.65 and 0.66% and total P rangingfrom 1.26 to 1.36%. The diets were fed to juvenile carpduring a 12-week feeding trial. The highest growth was obtained forfish fed the MM diet. The absorption and retention rates of P werehigher for the PF diet, whereas these values for N did not showtreatment-related differences. The total discharges per ton fish productionwere estimated to range between 7.8 and 9.2 kg for P andbetween 39.1 and 40.7 kg for N. These were lower than thefigures for Lake Kasumigaura, a main carp culture site, indicatingthat proper balancing of protein ingredients aids in efficientlylowering emissions from aquaculture.     

Feeding habits of Pacific pomfret Brama japonica inthe transition zone of the central North Pacific

ABSTRACT:   We examined the diets of three size groups of the Pacific pomfret Bramajaponica collected in April and May 2000 in the transition zoneof the central North Pacific. Amphipods, cephalopods and fish werethree of the most common prey groups of pomfret. Of the three size groups,small pomfret (11.0–19.9 cm standard length (SL))preyed mainly on amphipods and occasionally on cephalopods (mainlytransitional species Onychoteuthis borealijaponica ) and fish.(These prey amphipods and fish could not be identified to lowertaxonomic levels because they were too digested.) Medium and largepomfret (20.0–30.9 and 31.0–40.9 cm SL,respectively) preyed mainly on cephalopods (mainly O. borealijaponica ,but also on two subarctic species, namely Berryteuthis anonychus and Gonatopsisborealis ), suggesting that these cephalopod species ensure energyfor the northward migration of these two size groups in the transitionzone in the spring. The next most common prey for medium pomfretwas amphipods (mainly subtropical species Phronima sedentaria and Platyscelusovoides ), followed by fish (mainly Bathylagus sp.). However,in the case of large pomfret, fish (mainly Paralepididae sp. 'A')were the next most common prey, followed by amphipods (mainly P.sedentaria and P. ovoides ), indicating that the importanceof fish as prey increases with growth for medium and large pomfret.