Reconstruction of stratum corneum in organotypically cultured canine keratinocyte-derived CPEK cells

The stratum corneum of epidermis is an essential barrier against the external environment and water loss. This study aimed to develop an organotypic culture model that targets the reconstruction of the stratum corneum using canine keratinocyte-derived CPEK cells. The CPEK cells cultured at the air-liquid interface became stratified and formed a stratum corneum-like layer on stratum spinosum- and stratum granulosum-like layers. The CPEK cells in the stratum granulosum-like layer expressed the cornified cell envelope (CCE)-related proteins loricrin and keratinocyte differentiation-associated protein. Organotypically cultured CPEK cells were considered to form a CCE at the stratum granulosum-like layer, allowing the formation of a stratum corneum-like layer. The organotypic culture of CPEK cells could be useful for studying the barrier function of canine stratum corneum.     

Evaluation of the heat‐killed and dried cell preparation of Enterococcus faecalis against villous atrophy in early‐weaned mice and pigs

Early weaning induces villous atrophy in the small intestine (SI) of piglets. Oral administration of live lactic acid bacteria (LAB) can improve villous shortening. In this study, we evaluated the oral administration of a heat‐killed and dried cell preparation of Enterococcus faecalis (a LAB) strain EC‐12 against villous atrophy in early‐weaned mice (Experiment 1) and pigs (Experiments 2 and 3). Twelve 16‐days‐old mice were divided into two groups in Experiment 1: gavage of EC‐12 (10 mg/kg body weight (BW)/day), or control. On day 21, SI was collected. Eighteen 21‐day‐old pigs were divided into two groups in Experiment 2: gavage of EC‐12 (10 mg/kg BW/day), or control. After 10 days, the villous height of jejunum was measured. Six 21‐day‐old pigs were divided into two groups in Experiment 3: the basal diet supplemented with EC‐12 at 0.05%‐fed group, or the basal diet‐fed group. After 10 days, the villous height of jejunum was measured. The villous heights in SI were significantly higher by EC‐12 administration in all experiments. EC‐12 successfully improved the villous atrophy in the early‐weaned mice and pigs when EC‐12 was administered orally.     

A cytotoxic ribonuclease targeting specific transfer RNA anticodons

The carboxyl-terminal domain of colicin E5 was shown to inhibit protein synthesis of Escherichia coli. Its target, as revealed through in vivo and in vitro experiments, was not ribosomes as in the case of E3, but the transfer RNAs (tRNAs) for Tyr, His, Asn, and Asp, which contain a modified base, queuine, at the wobble position of each anticodon. The E5 carboxyl-terminal domain hydrolyzed these tRNAs just on the 3' side of this nucleotide. Tight correlation was observed between the toxicity of E5 and the cleavage of intracellular tRNAs of this group, implying that these tRNAs are the primary targets of colicin E5.     

Comparison of growth and mineral accumulation of two solanaceous species,Solanum scabrum Mill. (huckleberry) and S. melongena L. (eggplant), under salinity stress

Solanum scabrum Mill. (huckleberry) is widespread in West, East and Central Africa, where it constitutes one of the most important leafy vegetables. However, the salinity tolerance of this crop has not yet been assessed. The objective of this study was to assess the response of huckleberry to salinity stress in comparison with eggplant (S. melongena L.). Four-week-old seedlings of both species were subjected to two levels of salinity stress, 50 mM and 150 mM sodium chloride (NaCl), for 14 d. Leaf water potential of both species decreased with increasing salinity stress. This decrease was lower in huckleberry than in eggplant. Total dry weight and total leaf area were also decreased by salinity, and the reductions of total dry weight and total leaf area under the 50 mM treatment compared with the control were 25 and 18% in huckleberry, while they were 47 and 55% in eggplant, respectively. The increases in leaf sodium (Na) accumulation in the 50 and 150 mM treatments compared with the control were 65 and 66% for eggplant and 18 and 36% for huckleberry, respectively. Na accumulation in stem and root in huckleberry was higher than that of leaf, whereas it was the reverse in eggplant under both salinity treatments. Huckleberry accumulated less Na in the leaves than eggplant, suggesting that huckleberry might reduce the transport of Na to its leaves more effectively than eggplant. The decrease of potassium (K) accumulation and the increase of Na in leaves by salinity resulted in a higher Na/K ratio in leaves, but this trend was greater in eggplant than in huckleberry. The calcium (Ca) concentration in leaves of huckleberry was also increased by salinity, whereas that of eggplant was decreased. These results indicate that huckleberry is more tolerant to salinity than eggplant, and less decrease in leaf area associated with lower leaf Na and increased Ca concentrations may be important in enhancing quality and sustaining productivity of the crop under this stress.     

Molecular basis of the nitrogen response in plants

Nitrogen is an essential element for living organisms because it is a crucial constituent of biomolecules. Inadequate supply of usable nitrogen reduces plant growth and crop yield. The primary nitrogen sources for plants are nitrate and ammonium in soils, and plants have multiple layers of sensing and adaptive mechanisms that respond to the availability of these nutrients. The adaptive responses are called ‘nitrogen responses,’ which include morphological and physiological responses enabling plants to efficiently take up nitrogen and adapt to spatiotemporal fluctuations in nitrogen abundance in the field. In this review, we summarize the strategies that plants use to respond to changes in the nitrogen nutrient status in the soil and discuss different effects produced by nitrate and ammonium, emphasizing the important role of nitrate for plant growth. Recent studies revealed the molecular mechanism mediating the primary response to nitrate provision and the molecular mechanisms that coordinate the nitrogen response with responses to another macronutrient, phosphorus. We thus discuss these molecular mechanisms as well.     

Amino acids in stream water are essential for salmon homing migration

Upstream selective movement of chum salmon (Oncorhynchus keta), which were captured in the Osaru River, Hokkaido, Japan, in late spawning season, was investigated in a two-choice test tank consisted of two water inlet arms and one pool. Artificial home stream water that was prepared based on the compositions of amino acids and related substances of the Osaru River, and natural lake water flowed in each arm. Of 44 chum salmon tested, 28 fish showed upstream movement to one of the choice arm, and 24 fish (85.7%) of those moved fish were found in the arm running the artificial home stream water. When the artificial home stream water flowed from the left and right arms, 88.9% and 80% of fish were observed in the left and right arms, respectively. These results strongly support our hypothesis that amino acids dissolved in stream waters are home stream substances for salmon homing.     

Seasonal changes of hormones and muscle enzymes in adult lacustrine masu (Oncorhynchus masou) and sockeye salmon (O. nerka)

The upstream migration of adult anadromous fishes is characterized by physiological changes in responses to reproductive and energetic challenges. This study analyzed the physiological responses of lake-resident anadromous masu salmon (Oncorhynchus masou) and sockeye salmon (O. nerka) to migration in order to determine if these fish might serve as a suitable model for ocean-running populations and to differentiate between physiological responses to reproduction and to exercise-linked aspects of migration. Reproductive (estradiol, testosterone, 11-ketotestosterone, 17α,20β-dihydroxy-4-pregnen-3-one) and metabolically-linked (thyroxine, triiodothyronine) hormones showed similar patterns to ocean-running anadromous populations. White muscle pyruvate kinase, lactate dehydrogenase and malate dehydrogenase decreased with the onset of spawning season while white muscle citrate synthase, β-hydroxyacetyl CoA dehydrogenase, phosphofructokinase and glutamate oxaloacetate transaminase did not, suggesting that the former group of enzymes are responding to reproductive or food intake signals while the second group, which typically change during anadromous migration, may be responding to exercise-linked aspects of migration. This revised version was published online in August 2006 with corrections to the Cover Date.     

Weight-based population analysis: an estimation method

Generally, the individual weight of large fish is measured at landing, and thus, their weight composition is easily obtained. In this paper, we develop a method of population analysis using weight composition of fish, called weight-based population analysis, or WPA. WPA needs data of catch-at-weight, weight composition, weight from the growth and natural mortality M. We apply the method to the walleye pollack fishery in Funka Bay to evaluate its validity. The results show that the population size estimated from WPA reflects the features of population dynamics, and the estimated parameters reflect this walleye pollack fishery. Further, we compare the results of WPA with those of virtual population analysis (VPA) using catch-at-age data. The trend of population dynamics estimated using WPA was comparable to the results of VPA, suggesting that WPA can estimate population size as well as VPA.