Reproductive biology of the female Japanese mantis shrimp Oratosquilla oratoria (Stomatopoda) in relation to changes in the seasonal pattern of larval occurrence in Tokyo Bay, Japan

ABSTRACT:   The reproductive traits and the monthly larval abundance of the mantis shrimp Oratosquilla oratoria were investigated in Tokyo Bay, Japan, in 2002. The goal of the study was to elucidate the cause of changes in the monthly pattern of larval abundance from the 1980s to the 1990s as these changes relate to variation in the stock size of the adult shrimp. Oogenesis was divided into 10 stages by histological observation. The developmental stage of oocytes in an individual's ovary was synchronous, suggesting that almost all the oocytes in an ovary are spawned at the same time. The size at first maturity was estimated to be 7 ≤ body length ( BL ) < 8 cm. Fecundity was expressed as a function of BL , ranging from 19 300 eggs for 8 cm BL to 92 100 eggs for 14 cm BL . Small female shrimps (<10 cm BL ) spawned around August. Most large female shrimps (≥10 cm BL ) spawned around May, and some large female shrimps also spawned until September. Although most large female shrimps spawned in spring, the larval abundance was low before July and high from August onwards. The results suggest that a substantial decrease in the stock size of large individuals causes the low larval abundance before July.     

Performance of Bangladesh indigenous rice in a weed infested field and separation of allelopathy from resource competition

This study aimed to identify the potential allelopathic indigenous rice (Oryza sativa L. ssp. indica) varieties from Bangladesh using a performance study in a weed‐infested field and to assess the extent of allelopathic interference relative to resource competition in a glasshouse experiment. Six varieties – namely, “Boterswar,” “Goria,” “Biron” and “Kartiksail” as the most allelopathic, “Hashikolmi” as weakly allelopathic and “Holoi” as nonallelopathic – were raised following a nonweed control method. The infestation levels of weed species were calculated using Simpson's Diversity Index (SDI), which ranged from 0.2 to 0.56. However, a significant correlation coefficient (0.87, P < 0.001) was obtained from these field data compared with the root inhibition percentage from the laboratory bioassay, and the “Boterswar” variety was the most allelopathic. The interactions between the allelopathic variety “Boterswar,” weakly allelopathic variety “Hashikolmi” and Echinochloa oryzicola via a target (rice)‐adjacent (E. oryzicola) cogrowth culture were determined in a hydroponic arrangement. The relative competitive intensity (RCI) and the relative neighbor effect (RNE) values showed that the crop–weed interaction was facilitation for “Boterswar” and competition for “Hashikolmi” and E. oryzicola in rice/E. oryzicola cogrowth cultures. The allelopathic effects of “Boterswar” were much higher than the resource competition in rice/E. oryzicola cogrowth cultures. The converse was observed for “Hashikolmi.” Moreover, the mineral content of E. oryzicola was severely affected by “Boterswar”/E. oryzicola cogrowth cultures’ exudate solution. Therefore, the allelopathic potential of “Boterswar” variety might be useful for developing the weed‐suppressing capacity of rice, which will likely have a significant influence on paddy weed control.     

Effect of relationships among clinical mastitis incidence,reproductive performance,and culling rate on the lifetime of dairy cows at Hiroshima University Farm

Farm managers' decision to cull dairy cows is based on the cows' milk production, history of disorder(s), and reproductive performance, each of which affects dairy cows' lifetime (herd life and productive lifespan). We investigated the relationships among the incidence of clinical mastitis (CM), the reproductive performance, and the culling rate. We also assessed the effects of these relationships on the lifetimes of dairy cows, using the records made before and after the introduction of an automatic milking system (AMS) at Hiroshima University Farm. Milk yield, CM incidence density, and culling rate of dairy cows increased after the AMS introduction. The CM incidence was associated with an elongation of the calving interval in cows with the same parity. CM in the 1st parity might have caused the reductions of the cows' lifetime and their parity at culling. A higher age at first calving (AFC) was associated with an increase in culling rate but did not lead to a significant decrease in lifetime. Investigations of the factors mediating CM in the 1st parity or AFC with CM incidence or culling rate in the later stages might contribute to the control of lifetime of dairy cows.     

Proportions of melanocyte stimulating hormone-immunoreactive cells in the adenohypophysis of Silky fowl and hyperpigmentation-free cockerels

Alpha‐melanocyte stimulating hormone (α‐MSH) is one of the main regulators for melanocytes, and the adenohypophysis is one of the major tissues for the synthesis of this hormone. The Silky fowl is a characteristic breed of chicken with hyperpigmentation throughout the body. The involvement of the adenohypophysis in the hyperpigmentation of this breed is not known. In the present study, the proportion of melanocyte stimulating hormone‐immunopositive cells (MSH cells) in the adenohypophysis was immunocytochemically compared between Silky, Red Cornish × New Hampshire (RN) crossbred and Japanese bantam cockerels at 15 weeks of age. After the body and gland were weighed, the adenohypophyseal cells were enzymatically dispersed and immunostained for α‐MSH, and the immunopositive MSH cells were counted. The weights of the body and adenohypophysis were heaviest in the RN crossbred, followed by the Silky and lightest in the bantam cockerels. In contrast, the ratio between adenohypophysis and bodyweight was much larger in the Silky and the bantam than in the RN crossbreed (P < 0.05). The population of MSH cells in the adenohypophysis was larger in the Silky (14.3%) than in the RN crossbreed (8.0%) and the bantam (8.1%) cockerels (P < 0.05). From these results, it was concluded that prepubertal Silky cockerel have numerous MSH cells in the adenohypophysis suggesting a relationship to hyperpigmentation.     

Erythrocyte-replaced mouse model for Haemoparasite studies: comparison of NOD/shi-scid and C.B-17/Jcl-scid mouse upon acceptability of human erythrocytes

The erythrocyte-exchanged chimera mouse model has become to be a significant tool for studying animal and human (hu) protozoan haemoparasites, though the usefulness of this model varies depending primarily on the acceptability of xenogeneic red blood cells (RBC). To find a superior recipient in comparison with C.B-17/Jcl mouse with severe combined immuno-deficiency (scid) mutation, we examined in this report the non-obese diabetes (NOD)/shi-scid mouse, a recently available strain of SCID. When 2.5 x 10(8) of fluorescent dye-labeled hu-RBCs were transfused, C.B-17scid mouse eliminated them logarithmically by a simple linear regression, while NOD-scid mouse eradicated hu-RBCs by a unique two-step fashion, i.e., a potent but only briefly functioning RBC eradication followed by a weak steadily functioning step. The means of regression line constance +/- their standard deviations (SD) of 205 C.B-17scid and of 213 NOD-scid mice for their short- and long-lasting steps were -0.73 +/- 0.63, -0.53 +/- 0.25 and -0.16 +/- 0.10, respectively. Hu-RBC half-lives determined from these means of C.B-17scid mice and of NOD-scid mice for the short- and long-living steps were 3.6, 4.9 and 16.3 hr, respectively. Higher hu-RBC acceptability of NOD-scid mouse, especially at their long-lasting step, was also demonstrated under at an activated state of mouse innate immunity. Treatment with 1.0 mg heat-killed Candida cells caused an acceleration of hu-RBC elimination in both mouse strains but the magnitudes for the short- and long-living steps of NOD-scid mice evaluated by "stimulation index" were only 1/2.6 and 1/7.6 of C.B-17scid mice, respectively.     

The smell and odorous components of dried shiitake mushroom, <Emphasis Type="Italic">Lentinula edodes</Emphasis> IV: survey of trends in consumer preferences and changes in sensory evaluation

This study is part of an effort to improve the quality of dried shiitake mushrooms (Lentinula edodes) in accordance with consumer preference. Results are presented of a trend survey that examined the preferences of consumers using questionnaires combined with sensory evaluation. From the original preference (OP) survey, the distributions of OP divided by age class (AC) were statistically equal to the results obtained in 2000. The medians of OP for teenagers and twenties were “neutral” and “slightly like,” respectively. A firm preference change occurred between teenagers and those in their twenties. It is empirically realized that sensory intensity (SI) scores that were too high or too low led to a low hedonic preference (HP) score. The same tendency was seen for “neutralists” and “likers.” In addition, almost all distributions concerned with HP had no significant difference between 2000 and 2005; for example, that of SI divided by AC. These results showed that the preference for dried shiitake mushroom has been unaffected by the passage of the past 5 years. Dried shiitake mushrooms have been used from ancient times and for many dishes; therefore, the overall preference appears to have remained unchanged.     

Effects of current-year and previous-year PPFDs on shoot gross morphology and leaf properties in Fagus japonica

We investigated how shoot gross morphology and leaf properties are determined in Fagus japonica Maxim., a deciduous species with flush-type shoot phenology, in which all leaves are produced in a single flush at the start of each season. We examined relationships between current-year shoot properties and local light environment in a 14-m tall beech tree growing in a deciduous forest. Leaf number (LN), total leaf area (TLA), and total leaf length (SL) of the current-year shoot increased with increasing photosynthetic photon flux density (PPFD). Leaf thickness, dry mass per leaf area and nitrogen content on a leaf area basis increased, whereas the chlorophyll/N ratio decreased with increasing PPFD. To separate the effects of current-year PPFD from those of previous year(s), we artificially shaded a part of the uppermost leaf tier. Reciprocal transfers of beech seedlings between controlled PPFD regimes were also made. Characteristics of shoot gross morphology such as LN, TLA and SL were largely determined by the PPFD of the previous year. The exception was the length of the longest "long shoots" with many leaves, in which elongation appeared to be influenced by both previous-year and current-year PPFD. In contrast, leaf properties were determined by current-year PPFD. The ecological implications of our findings are discussed.     

Genetic variants of the unsaturated fatty acid receptor GPR120 relating to obesity in dogs

G protein-coupled receptor (GPR) 120 is an unsaturated fatty acid receptor, which is associated with various physiological functions. It is reported that the genetic variant of GPR120, p.Arg270His, is detected more in obese people, and this genetic variation functionally relates to obesity in humans. Obesity is a common nutritional disorder also in dogs, but the genetic factors have not ever been identified in dogs. In this study, we investigated the molecular structure of canine GPR120 and searched for candidate genetic variants which may relate to obesity in dogs. Canine GPR120 was highly homologous to those of other species, and seven transmembrane domains and two N-glycosylation sites were conserved. GPR120 mRNA was expressed in lung, jejunum, ileum, colon, hypothalamus, hippocampus, spinal cord, bone marrow, dermis and white adipose tissues in dogs, as those in mice and humans. Genetic variants of GPR120 were explored in client-owned 141 dogs, resulting in that 5 synonymous and 4 non-synonymous variants were found. The variant c.595C>A (p.Pro199Thr) was found in 40 dogs, and the gene frequency was significantly higher in dogs with higher body condition scores, i.e. 0.320 in BCS4–5 dogs, 0.175 in BCS3 dogs and 0.000 in BCS2 dogs. We conclude that c.595C>A (p.Pro199Thr) is a candidate variant relating to obesity, which may be helpful for nutritional management of dogs.