Validation of daily increment formation in otoliths of immature and adult Japanese anchovy <Emphasis Type="Italic">Engraulis japonicus</Emphasis>

In order to validate daily increment formation in otoliths of immature and adult Japanese anchovy Engraulis japonicus, three rearing experiments using chemical marking of otoliths were conducted on adult anchovy in summer 2004 and immature anchovy in summer 2005 and in winter 2006. In the two experiments conducted in summer, the number of otolith microincrements between alizarin complexone (ALC) marks showed that microincrements were formed daily. In the summer 2005 experiment, immature anchovy under conditions of reduced daily food rations also showed daily microincrement formation. Average increment width was 0.9 μm in adults and 1.8–3.1 μm in immature anchovy. In contrast, no clear increments were observed between ALC marks on the otoliths from the experiment in winter 2006, and scanning electron microscope (SEM) observations failed to confirm clear increment formation. We consider that low water temperatures (<13–14°C) restricted otolith growth and lowered the contrast between the discontinuous and the incremental zones of the otolith increments. For age estimation of Japanese anchovy, clear increments wider than about 1 μm in the otolith can be regarded as daily increments. However, daily age estimation of immature and adult anchovy that experience low water temperatures in winter may be difficult due to the obscurity of the increments.     

In situ growth and mortality of juvenile Acropora over 2 years following mass spawning in Sekisei Lagoon,Okinawa (24°N)

The growth of Acropora in Sekisei Lagoon was investigated in situ using ceramic coral settlement devices (CSDs) and marine blocks (MBs) with small holes on their surfaces that were deployed prior to a mass spawning event. Acropora that had settled in 10-mm holes on the upper surface of the MBs were found to have grown inwards after 348 days post-mass spawning. After 733 days, the colonies had grown outwards, encrusting the blocks and attaining a maximum diameter of 21.5 mm (3.7 mm). CSDs that had been stacked above each other on frames were separated and observed in situ on 405 and 764 days after mass spawning. After 405 days, the maximum diameter of the encrusting Acropora was 7.6 mm (±2.4 mm), which increased to 19.4 mm (±5.5 mm) after 764 days, with 30% of colonies extending short branches. The length of the branches of Acropora grown on the CSDs fixed to the MBs 3 months after the mass spawning event exceeded the size of the encrusting portion of the colony 629 days after spawning. The mortality of colonies between 1 and 2 years was slight, with the temperatures conducive to coral bleaching that occurred during the study also having only a slight effect.     

Seasonal changes in otolith and somatic growth in age-0 Pacific saury <Emphasis Type="Italic">Cololabis saira</Emphasis>

We evaluated the seasonal changes in otolith and somatic growth of age-0 Pacific saury Cololabis saira in 223 fish collected between June and November 2002. We calculated the age in days of each individual by measuring otolith growth increments under a scanning electron microscope. The age was correlated with body length and otolith radius. We also observed seasonal changes in the rate of increase in body length and otolith radius and in the pattern of otolith growth. Until August, both body length and otolith radius increased with age. Thereafter, the otolith radius continued to increase, whereas the rate of somatic growth decreased. As a result, the ratio of otolith radius to body length increased. After August, the percentage of otoliths with unreadable increments on their edge increased due to the formation of hyaline zones. Otoliths grew both radially and in thickness until July, but gradually stopped growing in thickness after August. Beginning in October, more than 80% of otoliths only grew radially. After August, the otolith not only continued growing but the morphological growth pattern also changed.     

Expression of podoplanin in various types of feline tumor tissues

Podoplanin is expressed in various human tumors where it promotes tumor progression, epithelial-mesenchymal transition, and distant metastasis. Podoplanin is also expressed in cancer-associated fibroblasts and induces tumor malignancy. The objective of this study was to evaluate podoplanin expression in various types of feline tumor tissues. Immunohistochemical analysis revealed that podoplanin was expressed in cells of 13/15 (87%) squamous cell carcinomas and 5/19 (26%) fibrosarcomas. Moreover, cancer-associated fibroblasts expressed podoplanin in most tumor types, including 18/21 (86%) mammary adenocarcinoma tissues. Our findings demonstrate that various types of feline tumor tissues expressed podoplanin, indicating the importance of the comparative aspects of podoplanin expression, which may be used as a novel research model for podoplanin biology.     

Plasmodium (Bennettinia) juxtanucleare infection in a captive white eared-pheasant (Crossoptilon crossoptilon) at a Japanese zoo

An adult male white eared-pheasant (Crossoptilon crossoptilon) at a Japanese zoo exhibited lethargy and emaciation. Microscopic examination of a blood smear revealed a haemosporidian parasitic infection. Based on the morphological characteristics and molecular analysis of the parasite, it was identified as Plasmodium (Bennettinia) juxtanucleare. This is the first report of P. juxtanucleare infection in bird species belonging to the genus Crossoptilon. Caution against avian malaria infection is required for the conservation of endangered bird species in zoos.     

A novel mouse wound model for scar tissue formation in abdominal muscle wall

Hypertrophic scars found on the human body rarely develop in experimental animals, possibly due to their looser skin structure. This makes it difficult to understand the genesis of scar lesions. Therefore, appropriate animal models are urgently needed. In this study, we established a novel experimental model of a scar-forming wound by resecting a small portion of the abdominal muscle wall on the lower center of the abdomen in C57BL/6N mice, which are exposed to contractive forces by the surrounding muscle tissue. As a low-tension control, a back skin excision model was used with a splint fixed onto the excised skin edge, and granulation tissue formed on the muscle fascia supported by the back skeleton. One week after the resection, initial healing reactions, such as fibroblast proliferation, occurred in both models. However, after 21 days, lesions with collagen-rich granulation tissues, which were also accompanied by multiple nodular/spherical-like structures, developed only in the abdominal wall model. These lesions were analogous to scar lesions in humans. Therefore, the animal model developed in this study is unique in that fibrous scar tissues form under physiological conditions without using any artificial factors and is valuable for studying the pathogenesis and preclinical treatment of scar lesions.     

Experimental study on the influence of dissolved organic matter in water and redox state of bottom sediment on water quality dynamics under anaerobic conditions in an organically polluted water body

To understand aquatic environmental deterioration due to the anoxic state in an organically polluted water body, water quality dynamics under anaerobic conditions were examined through beaker-scale water quality monitoring. This study focused on the dynamic properties of NO₃–N, NH₄–N, PO₄–P, and sulfide from the biochemical reactions point of view, and based on anaerobic respiration activities, such as denitrification, iron reduction, and sulfate reduction. The specific aims of this study were to quantitatively estimate the impacts of the oxidative/reductive state of the sediment surface and the high/low concentrations of dissolved organic matter on the dynamic properties of water quality under anaerobic conditions. The beaker-scale water quality monitoring was carried out through continuous measurements of dissolved oxygen and oxidation–reduction potential (ORP), as well as periodic observations of water quality parameters for six cases that are composed from combinations of three experimental conditions: (1) concentration of dissolved organic carbon (DOC); (2) redox state of the sediment; and (3) concentration of NO₃–N. As a result, the temporal changes in ORP under anaerobic conditions exhibited a five-step process of decline without these conditions. Also, high DOC concentrations and oxidative states of the bottom mud accelerated the release of PO₄–P and sulfide generation through promoting biological iron reduction and sulfate reduction, because these conditions increase respiratory substrates for anaerobic microorganisms, such as iron and sulfate-reducing bacteria. It was concluded that our results would provide important information about the mechanisms of aqueous environmental deterioration due to organic pollution in closed water bodies.     

Establishment of shell growth analysis technique of juvenile Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>: semidiurnal shell increment formation

ABSTRACT:   The conventional acetate peel method was modified to analyze the shell growth pattern of juvenile Manila clam Ruditapes philippinarum as small as 2 mm in shell length (SL). In the outer shell layer along the axis of maximum growth, two types of growth increments were observed: distinct increments and indistinct increments, which, respectively, do and do not continue to the middle shell layer. The distinct increments were found to be formed every two days in intertidal and shallow subtidal zones by field enclosure experiments of juveniles with datum points marked with alizarin complexone. Growth patterns of juveniles (12 mm SL) collected from the Seaside Park of Yokohama in Tokyo Bay were analyzed to confirm the modified method. Mean daily shell growth rate from April to July 2005 ranged 120–142 μm/day, which was reasonable as compared with previous studies. It was impossible to backcalculate the growth to the settlement size (i.e. 0.2 mm SL) because of erosion of the outer shell surface, and the smallest backcalculated minimum shell length was 0.8 mm. Fluctuations in daily growth rate were high, ranging 29–315 μm/day, and did not show a clear two-weekly rhythm.     

Improving the accuracy of estimating blood calcium concentration in Holstein cows using electrocardiographic variables

We previously reported the possibility of using the electrocardiogram variable to estimate blood calcium (Ca) concentration in dairy cows based on the strong positive correlation between the blood Ca concentration and the inverse of the corrected ST peak interval (STc⁻¹). To improve the accuracy of the estimation of blood Ca concentration, we investigated the relationship between blood Ca concentration and STc⁻¹ for each postpartum day and available variables other than STc⁻¹. We measured multiple variables (milk yield, calving number, age, body temperature, etc.), including serum total Ca concentration (tCa), blood ionized Ca concentration (iCa) and STc⁻¹ in 462 Holstein cows on days 0, 1, 2, 3, 5, and 7 postpartum. A very high correlation was observed between iCa and tCa. The association between tCa and STc⁻¹ for each postpartum day had a high coefficient of determination of 0.61–0.79 postpartum 0–2 days but decreased after the third day. In the investigation using the data from postpartum days 0–2, STc⁻¹, heart rate interval, calving number, and age were highly correlated with tCa. In addition, a multiple regression equation was obtained with tCa as the objective variable and STc⁻¹ and calving number as explanatory variables. The estimation accuracy was improved as compared with the simple regression equation using only STc⁻¹ as the explanatory variable. This multiple regression equation was used for 11 cows suspected of having hypocalcemia, and it was able to correctly detect cows requiring early treatment, except for one cow.     

Impact of Natural Forest Protection Program policies on forests in northeastern China

This study analyzes the effects of the Natural Forest Protection Program (NFPP) on the restoration of forest resources in