A modeling approach for assessing rice cropping cycle affected by flooding,salinity intrusion,and monsoon rains in the Mekong Delta,Vietnam

We developed a crop scheduling model for rice cultivation in the Vietnam Mekong Delta (VMD), focusing on the adaptive behavior of crop planning to various water resource constraints. In addition, we also examined the effects of environmental change on rice cultivation in the last decade. In the VMD, multiple rice cropping is practiced under a variety of adverse water conditions, including flooding, salinity intrusion, and irregular monsoon rains. These environmental changes influence the durations of growing seasons and the number of crops per year, resulting in changes in productivity. To validate the performance of the model, we compared model estimates for the heading date and changes in leaf area index at nine sites with estimates of these parameters derived from MODIS satellite time series data for the period 2002–2006. The root mean square errors of heading date between the modeled and satellite data in the upper, middle, and coastal regions of the delta were 17.6, 11.2, and 13.0 days, respectively. Based on the model, we examined case studies to assess the changes in cropping cycles and crop failures in the VMD due to extreme flooding in 2000 and salinity intrusion in 2004 by applying evaluation indices defined by available period for cultivation (APC) and safe margin for cropping (SMC) which is defined as the marginal time between APC and the period required for cultivation. Findings of case studies suggested that a small difference in the SMC of the cropping pattern is critical to the stability and productive capacity of the rice crop.     

Effects of synthetic kisspeptin peptides and GnRH analogue on oocyte growth and circulating sex steroids in prepubertal female chub mackerel (Scomber japonicus)

In recent years, kisspeptin peptides, encoded by kiss genes have been used to manipulate reproductive processes in farmed animals, including fish. Our previous studies demonstrated that the chub mackerel brain expresses kiss1 and kiss2 and intramuscular injection of synthetic Kiss1 pentadecapeptide (Kiss1‐15) but not Kiss2 dodecapeptide (Kiss2‐12) accelerates spermatogenesis in prepubertal male chub mackerel (Scomber japonicus). In the present study, we evaluated their effects in prepubertal female chub mackerel. The gonadosomatic index (GSI) values of experimental fish did not show any significant changes. Condition factor (CF) values increased significantly in Kiss1‐15 treated fish, in comparison with control and GnRH analogue (GnRHa) injected fish. Histologically, only perinucleolar oocytes were found in all experimental fish. However, Kiss and GnRHa treated fish showed a significant increase in the perinucleolar oocyte diameter, in comparison with the control fish. Gene expression analyses revealed decreased expression of gnrh1 in the telencephalon‐preoptic region of the brain of Kiss2‐12 and GnRHa injected fish, in comparison with control fish. In contrast, GnRHa injected fish exhibited higher levels of fshβ in the pituitary, with no changes in the levels of lhβ among different treatments. Levels of circulating sex steroids, testosterone, and estradiol‐17β were significantly higher in Kiss1‐15 injected fish, in comparison with control fish. These results indicate that synthetic kisspeptin peptides and GnRHa can induce oocyte growth in prepubertal female chub mackerel.     

Assessment of management of direct seeded rice production under different water conditions in Cambodia

In order to assess direct seeding of rice technology to cope with future agricultural labor shortage in Cambodia, agronomic experiments were conducted in 2005 and 2006 to compare direct seeding with transplanting under three water conditions (non-flooded, shallow flooded, and deep flooded conditions) with/without weed control by herbicides (bentazone and cyhalofop-butyl) for two Cambodian rice varieties (shorter stature and early maturity Sen Pidao, taller stature and longer maturity Phka Rumduol). Average rice yield in 2 years was lower in direct seeding (341 g m⁻²) than transplanting (404 g m⁻²), but interaction components with year, varieties, water conditions, and weed management were significant, and the attained maximum yield of direct seeding (510 and 464 g m⁻² for Phka Rumduol variety in shallow flooded condition with weeding in 2005 and 2006, respectively) was similar to that of transplanting. Plant length and dry weight of rice were reduced in non-flooded and deep flooded conditions compared with shallow flooded condition, and grain yield was the highest in shallow flooded condition. Yield advantage of Phka Rumduol over Sen Pidao increased under direct seeding, particularly under non-flooded conditions in 2005 because weed infestation was more suppressed in Phka Rumduol even without weeding. Increase in 100 g m⁻² of weed infestation prior to heading (dry weight basis) reduced about 20% of attainable yield with weed control. This study identified importance of stature and growth duration of rice varieties and presence of standing water as well as the weed control, in order to develop and extend direct seeding in the Cambodia.     

Advances in table grape breeding in Japan

In Japan, few grape cultivars related to Vitis vinifera existed 200 years ago, on account of Japan’s high rainfall. Many V. labruscana and vinifera cultivars were introduced to Japan in the 19th century. Labruscana was grown instead of vinifera, mainly because of severe disease problems and a high incidence of berry cracking. Grape breeding for table use started in the 20th century, with the goal of combining the berry quality of vinifera with the ease of cultivation of labruscana. By 1945, three strategies were used: 1) crossing among introduced diploid vinifera and vinifera-related cultivars of Japanese origin, 2) interspecific crossing in tetraploid cultivars, and 3) interspecific crossing in diploid cultivars, resulting in ‘Neo Muscat’, ‘Kyoho’, and ‘Muscat Bailey A’. Later, tetraploid interspecific crossing over generations developed many ‘Kyoho’-related cultivars, including ‘Pione’, many of which have large berries, intermediate flesh texture between the two species, a labruscan or neutral flavor, and moderate disease resistance. Interspecific diploid crossing over generations developed ‘Shine Muscat’ in 2006, with large berries, crispy flesh, a muscat flavor, no cracking, seedless fruit by gibberellin application, and moderate resistance to downy mildew and ripe rot.     

Evaluation of Aqueous Biphasic Electrophoresis System Based on Halide-Free Ionic Liquids for Direct Recovery of Keratinase

Aqueous biphasic electrophoresis system (ABES) incorporates electric fields into the biphasic system to separate the target biomolecules from crude feedstock. Ionic liquid (IL) is regarded as an excellent candidate as the phase-forming components for ABES because of the great electrical conductivity, which can promote the electromigration of biomolecules in ABES, and thereby enhances the separation efficiency of the target biomolecules from crude feedstock. The application of electric fields to the conventional biphasic system expedites the phase settling time of the biphasic system, which eases the subsequent scaling-up steps and reduces the overall processing time of the recovery process. Alkyl sulphate-based IL is a green and economical halide-free surfactant when compared to the other halide-containing IL. The feasibility of halide-free IL-based ABES to recover Kytococcus sedentarius TWHK01 keratinase was studied. Optimum partition coefficient (K_e = 7.53 ± 0.35) and yield (Y_T = 80.36% ± 0.71) were recorded with IL-ABES comprised of 15.0% (w/w) [EMIM][ESO₄], 20.0% (w/w) sodium carbonate and 15% (w/w) crude feedstock. Selectivity (S) of 5.75 ± 0.27 was obtained with the IL-ABES operated at operation time of 5 min with 10 V voltage supplied. Halide-free IL is proven to be a potential phase-forming component of IL-ABES for large-scale recovery of keratinase.     

A case of spontaneous Zymbal’s gland carcinoma with lung metastasis in an aged Fischer 344 rat

Zymbal’s gland neoplasms are induced in rats through the administration of various carcinogens, but spontaneous neoplasia is rare. This report describes a spontaneous Zymbal’s gland carcinoma with lung metastasis found in an aged male Fischer 344 rat. Macroscopically, the dome-like tumor nodule, approximately 30 mm in diameter with ulceration, was located near the ear canal of the rat. No healthy tissue or structure of Zymbal’s gland was identified on the corresponding side, while the normal salivary glands and a lacrimal gland were observed. Histologically, a large part of the tumor mass was occupied by poorly differentiated neoplastic cells, the shapes of which were oval to polygonal or fusiform. Additionally, clusters of sebaceous-like foamy cells and squamous metaplasia with prominent keratinization were observed. Tumor cells were found to metastasize to the lung; these cells displayed histological similarities, including a sebaceous gland-like pattern, to those in the primary site. The tumor cells were immunohistochemically positive for cytokeratin AE1/AE3 or vimentin but negative for CD68, S100, α-smooth muscle actin, von Willebrand factor, and desmin. Our results indicate that the tumor was a poorly differentiated Zymbal’s gland carcinoma with lung metastasis.     

Review of population dynamics and management of small pelagic fishes around the Japanese Archipelago

Fisheries Science - Population dynamics of small pelagic fishes (SPF) and their management in Japan were reviewed for Japanese sardine Sardinops melanostictus, Japanese anchovy Engraulis japonicus,...     

Life-history traits of eight <Emphasis Type="Italic">Lethrinus</Emphasis> species from two local populations in waters off the Ryukyu Islands

The number of growth rings was counted on broken and burnt otoliths of eight Lethrinus spp. from two local populations: Lethrinus atkinsoni, L. harak, L. miniatus, L. nebulosus, L. obsoletus, L. ornatus, L. ravus, and L. rubrioperculatus, collected from 1985 to 1996 in waters off the Ryukyu Islands. Growth rings were revealed to be formed annually from about October to June by marginal analysis. In addition to obtaining the three parameters in von Bertalanffy growth equation and the maximum age in specimens, the relationship between age and both ovarian maturity rate and sex ratio (percentage female) was analyzed. The age at 50% of ovarian maturity was the lowest at 1–2 years old in L. harak, L. ravus, and L. rubrioperculatus and was the highest at approximately 4 years old in L. nebulosus. The age at which the sex ratio decreased to 50% due to sexual transition from female in protogynous hermaphrodite species was the lowest at 3–4 years old in the L. atkinsoni Okinawa population and was the highest at 7–8 years old in L. miniatus. The oldest maximum age for specimens was 26 years in L. nebulosus and the youngest maximum age was 12 years in L. ornatus.     

Immunoreactive changes in pituitary FSH and LH cells during seasonal reproductive and spawning cycles of female chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis>

The physiological functions of pituitary gonadotropins (GtHs) are well established in higher vertebrates, whereas those in teleosts are still poorly understood. To describe the role of GtHs during gonadal development of female chub mackerel Scomber japonicus, changes in follicle-stimulating hormone (FSH) and luteinizing hormone (LH) cells were investigated immunohistochemically during the seasonal reproductive and spawning cycles. FSH and LH cells were identified in the different cell types of the proximal pars distalis (PPD); FSH cells were located in the central PPD, whereas LH cells were localized along the border of the pars intermedia. To examine changes in FSH and LH cells, the percentage of FSH or LH cell-occupying area in the PPD was evaluated and represented as FSHβ-immunoreactive (ir) or LHβ-ir levels, respectively. FSHβ-ir levels increased significantly from immature to the completion of vitellogenesis, whereas LHβ-ir levels were maintained at high levels from early vitellogenesis to post-spawning. During the spawning cycle, which consisted of four stages from just after spawning to the next oocyte maturation, both FSHβ-ir and LHβ-ir levels showed no significant changes among different stages; however, LHβ-ir levels remained relatively high, and FSHβ-ir levels were constantly low. These results suggest that both FSH and LH may be involved in vitellogenesis and LH may act at final oocyte maturation in female chub mackerel, although the role of FSH during the spawning cycle is still unclear.     

Immunohistochemical observations of vitellin synthesis and accumulation processes in ovary of Ezo abalone <Emphasis Type="Italic">Haliotis discus hannai</Emphasis>

Ovarian follicle cells are the site of yolk protein synthesis in the Ezo abalone Haliotis discus hannai. In this study, histological observations of ovarian follicle cells were conducted in H. discus hannai by immunocytochemical and in situ hybridization methods focusing on their function of yolk protein synthesis. An antibody raised against purified yolk protein (vitellin, Vn) recognized yolk granules in oocytes, and ovarian follicle cells adjacent to the oocytes under yolk accumulation were stained positively with both anti-Vn antibody and an antisense probe for vitellogenin (the precursor for vitellin, Vtg) mRNA. These results indicate that the abalone Vtg gene is transcribed and translated in the ovarian follicle cells. In oocytes in the early phase of yolk accumulation, positive reactions with the antibody appeared first in the stalk part, and the follicle cells adjacent to the stalk were also stained positively. These observations imply local transport of yolk protein from the follicle cells to the oocyte through an extracellular space around the oocyte stalk. Ovarian follicle cells changed their morphological characteristics and reactivity to the antibody in close relation to the stages of the adjacent oocyte, which suggests the presence of functional interactions between follicle cells and oocytes in the course of yolk protein synthesis and accumulation.