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281.
The ark shell Anadara granosa is a species peculiar to the Ariake Sound. To determine why distribution of A. granosa in Japan is largely confined to this area, we examined feeding and growth of A. granosa as functions of environmental and biological variables. The results were compared with those of another ark shell Scapharca subcrenata, which is ubiquitous in Japan. Feeding experiments indicated that A. granosa is eurythermal and euryhaline, as is S. subcrenata, but is adapted to temperature slightly higher than S. subcrenata. Weight-specific clearance rate (CR) of A. granosa as a function of soft-body dry-weight (w) followed the power function of w (CR=2.7×w
−0.37), with coefficient and exponent very close to those for S. subcrenata. Growth rate of A. granosa increased linearly with daily ration, similar to S. subcrenata. Thus, feeding and growth characteristics of A. granosa were comparable to those of S. subcrenata and no ‘peculiarities’ of the former were detected. Therefore, the factors that make A. granosa a species restricted to the sound are probably not directly related to feeding or growth characteristics. 相似文献
282.
The rate of oxygen consumption of minced whole body was determined volumetrically, as an indication of metabolic rate in vitro (M
in vitro
), at 20°C in porgy Pagrus major ranging from 0.0002 g (just after hatch) to 2.9 g (67 days old) in body mass. A triphasic relationship was found between M
in vitro
of individual fish (l.min–1) and wet body mass W (g). During the prolarval stage accompanied with the transitional period to the postlarval stage (0.00020–0.00023 g, 0–6 days old), the mass-specific metabolic rate in vitro (M
in vitro
/W in l.g–1.min–1) increased with age (D in days) as expressed by an equation M
in vitro
/W = 3.88 + 0.74/D. During the postlarval stage (0.00031–0.003 g, 8–22 days old), M
in vitro
/W remained almost constant, independent of body mass following an equation M
in vitro
/W = 5.24 W–0.085. During the juvenile and adolescent stages (0.0047–2.9 g, 30–67 days old), M
in vitro
/W decreased with increasing body mass following an equation M
in vitro
/W = 1.66 W–0.235. These results correspond with the triphasic relationship between metabolism in vivo and body mass observed in intact porgy of 0.0002–270 g (Oikawa et al. 1991). It is concluded, therefore, that the dependence of mass-specific metabolic rate on body size exists in vitro as well as in vivo, during the early stages in the porgy. Based on these results, factors controlling the metabolism-size relationship are discussed. 相似文献
283.
ABSTRACT: To assess the roles of the ark shell Scapharca subcrenata in material cycling in the northern part of Ariake Sound (Mae-no-umi), Japan, filtration of the ark shell fed on small diatoms was examined as a function of environmental and biological variables. The clearance rate ( CR ) specific to the soft-body dry weight ( w ) of the animals (shell length, 8–26 mm) followed a power function of w with an exponent of −0.35. Over the range of 10–20°C, CR increased 2.7 times, and filtration did not occur below a salinity of 14 practical salinity unit. Neither food concentration (10–40 µg/L of chlorophyll- a ) nor weight-specific daily ration (0.5–6%/day in terms of ash-free dry weight) notably affected CR . Using this information on CR as well as data regarding abundance and size distribution, the population filtration rate was calculated to be 1.6 m3 /m2 per day in the ark-shell culturing ground of Mae-no-umi (mean water depth, ∼3 m), corresponding to the potential to locally process a volume of water equivalent to the water column within 2 days. Because the culturing ground accounts for 12% of Mae-no-umi (mean water depth, ∼8 m), the ark shell seems to play an important role in its material cycling. 相似文献
284.
Muneaki Takahata Hidehiro Toh Akiyo Nakano Misako Takagi Masaru Murakami Yasuo Ishii Tatsuya Takizawa Soichi Tanabe Hidetoshi Morita 《Animal Science Journal》2014,85(2):158-163
Bifidobacterial plasmids reported so far are derived from a limited number of strains and plasmids of bifidobacterial type strains isolated from humans are unknown. We found that Bifidobacterium kashiwanohense JCM 15439 (type strain) isolated from a healthy infant contained two cryptic plasmids, designated pBBKW‐1 and pBBKW‐2. We determined and analyzed the complete sequences of both plasmids. pBBKW‐1 (7716 bp) was predicted to replicate by a rolling‐circle mechanism and encode six protein‐coding genes, two of which are putative replication proteins. pBBKW‐1 seems to be a cointegrate plasmid containing two copies of the plasmid pMG1 from Bifidobacterium longum. pBBKW‐2 (2920 bp) was predicted to encode six protein‐coding genes and be a theta‐type replicating plasmid, which has been reported to be more stable than a rolling circle‐type replicating plasmid frequently found in bifidobacteria. Our finding will provide new insights into safe recombinant plasmid constructions for humans. 相似文献
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290.
Keisuke KOZAI Takuo HOJO Shota TOKUYAMA Anna Z SZóSTEK Masashi TAKAHASHI Miki SAKATANI Yasuo NAMBO Dariusz J SKARZYNSKI Kiyoshi OKUDA 《The Journal of reproduction and development》2014,60(2):150-154
Regression of the corpus luteum (CL) is characterized by a decay in progesterone
(P4) production (functional luteolysis) and disappearance of luteal tissues
(structural luteolysis). In mares, structural luteolysis is thought to be caused by
apoptosis of luteal cells, but functional luteolysis is poorly understood.
20α-hydroxysteroid dehydrogenase (20α-HSD) catabolizes P4 into its biologically
inactive form, 20α-hydroxyprogesterone (20α-OHP). In mares, aldo-keto reductase (AKR)
1C23, which is a member of the AKR superfamily, has 20α-HSD activity. To clarify whether
AKR1C23 is associated with functional luteolysis in mares, we investigated the expression
of AKR1C23 in the CL in different luteal phases. The luteal P4 concentration
and levels of 3β-hydroxysteroid dehydrogenase (3β-HSD) mRNA were higher in the mid luteal
phase than in the late and regressed luteal phases (P<0.05), but the level of 3β-HSD
protein was higher in the late luteal phase than in the regressed luteal phase
(P<0.05). The luteal 20α-OHP concentration and the level of AKR1C23
mRNA were higher in the late luteal phase than in the early and mid luteal phases
(P<0.05), and the level of AKR1C23 protein was also highest in the late luteal phase.
Taken together, these findings suggest that metabolism of P4 by AKR1C23 is one
of the processes contributing to functional luteolysis in mares. 相似文献