Effects of estrogen on growth hormone pulsatility in peripheral blood and neuropeptide profiles in the cerebrospinal fluid of goats

We previously reported that growth hormone (GH) pulses were negatively associated with neuropeptide Y (NPY) profiles in cerebrospinal fluid (CSF) of the third ventricle of Shiba goats. In addition, while most GH pulses were coincident with GH-releasing hormone (GHRH) pulses, there was no correlation between GH and somatostatin (SRIF) levels. The present study was performed to elucidate the relationship between GH pulses and these neuropeptide levels in CSF when estradiol (1.0 mg/head) was subcutaneously administered to ovariectomized goats. CSF and plasma samples were collected every 15 min for 18 h (from 6 h before to 12 h after injection). GH levels in peripheral blood and GHRH, SRIF and NPY levels in CSF were measured by radioimmunoassay. Pulse/trough characteristics and correlations were assessed by the ULTRA algorithm and cross-correlation analysis. Before estradiol was injected, significant coincidence was found between GHRH pulses and GH pulses, and negative coincidence was found between NPY troughs and GH pulses. Six to 12 h after estradiol injection, the amplitude and area under the curve (AUC) of the GH pulses were markedly increased. The duration and AUC of the GHRH pulses in the CSF were also increased, and stronger synchrony of GHRH with GH was observed. In contrast, the baseline of NPY was significantly decreased, and the negative correlation between the GH pulses and NPY troughs disappeared. The parameters of SRIF troughs were not clearly changed. These observations suggest that estrogen enhances the pattern of secretion of GH in the goat via enhancement of GHRH pulses and decrease of NPY levels.     

METABOLITE PROFILING OF SHOOT EXTRACTS,ROOT EXTRACTS,AND ROOT EXUDATES OF RICE PLANT UNDER PHOSPHORUS DEFICIENCY

We applied a metabolite profiling technique to investigate root exudates under phosphorus (P) deficiency. Oryza sativa was grown in culture solution containing three P levels (0, 1, and 8 mg P L^?1). Shoot extracts, root extracts, and root exudates were obtained from 18 and 23-day-old plants and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Eighty, 90, and 65 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively. Sixty-three to eighty-four percent of the metabolites were exuded to the rhizosphere. More than 33% of the metabolites in the root exudates showed higher concentration at low P than at high P. On the other hand, only 14% of the metabolites in the root extracts showed lower concentration at low P than at high P. These results suggest that rice roots actively release many metabolites in response to P deficiency.     

Radiocesium transfer into the fruit of deciduous fruit trees contaminated during dormancy

Following the accident at the Tokyo Electric Power Company, Fukushima Daiichi Nuclear Power Plant (FDNPP), radiocesium (¹³⁴Cs + ¹³⁷Cs) concentrations in deciduous mature fruits were determined in orchards in the northern area of Fukushima Prefecture. At the time of the nuclear accident, most deciduous fruit trees were in the dormant stage prior to bud burst. To evaluate the relationship between radiocesium deposition in the soil and fruit contamination, radiocesium concentrations were measured from the 5-cm topsoil and from six fruit species across 17 orchards in 2011. The vertical distribution of radiocesium in the topsoil (0–30 cm in depth) and its spatial distribution in the 5-cm topsoil underlying the tree canopy of a peach, Prunus persica (L.) Batsh, orchard (“Akatsuki” cultivar) were also investigated. Significant correlations between the radiocesium concentration in the mature fruit and that in the 5-cm topsoil layer were observed for the 17 orchards as well as for the trees of the peach orchard. However, 93% of the ¹³⁷Cs found in the 30-cm soil core was retained within the top 3 cm of the soil in the peach orchard. Considering the profile of the root of this deciduous fruit tree, we assumed a negligible level of radiocesium uptake via the roots. However, the possibility of inward migration via the bark was undeniable, because some radiocesium adhered to the tree canopy before bud burst while depositing on the soil surface. Additionally, transfer factors for peach and grape, hybrid of Vitis labrusca L. and Vitis vinifera L., from young, uncontaminated trees cultivated with contaminated soil were lower than those previously reported.     

Testes maturation of reared Pacific bluefin tuna Thunnus orientalis at two-plus years old

ABSTRACT:   Stable reproduction is essential for supplying artificially hatched fish to tuna aquaculture. We observed testes maturation in reared Pacific bluefin tuna (PBT) Thunnus orientalis at 2+ years of age. The incidence of males with mature testes was 25.0%, and 40% of the males had developing testes that contain spermatozoa, while oocytes of the same aged females were not mature. These fish were wild-caught at 0+ years old in August 1997 and the gonads were examined in October 1998 and January–February 2000. Therefore, the age at examination in 2000 was estimated to be 2 years and 7–10 months old considering the spawning season of the wild PBT and the size when captured. Histological examination of the matured and developing testes showed that they contained spermatozoa, spermatids, spermatocytes, and spermatogonia. All the spermatozoa were observed to be motile in sea water under light microscopy. From the results of this and previous studies, matured males are probably fertile for at least 5 months a year in Kushimoto. The testes maturation observed at young age in captivity is considered promising to reduce the cost of broodstock maintenance for the juvenile production of PBT, especially if the sperm are cryopreserved.     

Among-year variation in deer population density index estimated from road count surveys

A method for obtaining a relative deer population density index with low cost and effort is urgently needed in wildlife protection areas that need their own deer management guidelines. We recorded the number of deer sighted during our daily trips on forest roads by car in Ashiu Forest at Kyoto University, Japan, beginning in 2006. We used generalized additive mixed models (GAMMs) to estimate among-year trends in the number of deer sighted. We applied models for the total number of deer (TND), number of adults (NA), and number of fawns (NF) sighted, which included both current-year and 1-year-old fawns. Full models included the terms of year (2007, 2008, 2009, and 2010), weather (fine, cloudy, and rain/snow), and nonlinear effects of season (date) and time (time). The optimal GAMMs for TND, NA, and NF did not include the effect of weather but included those of time, date, and year. The detected among-year trends in deer population may be influenced by differences in snow environments among the years. The modeling of road count data using GAMM quantitatively determined among-year variation in the number of deer sighted. This trend was similar to that of the population density estimated using a block count survey conducted in Ashiu Forest.     

High temperature and low solar radiation during ripening differentially affect the composition of milky-white grains in rice (Oryza sativa L.)

ABSTRACT

Temperatures and solar radiation during ripening critically affect grain appearance in rice (Oryza sativa L.). Climatic factors to induce chalky grains were analyzed under the experimental conditions of high-temperature and shading treatment and also under the ambient condition in a high-temperature-prone region of Japan. The frequency of white-back (WB) and basal-white (BW) grains correlated with temperature and solar radiation, whereas that of milky-white (MW) grains was not correlated, suggesting that complicated climatic factors are involved in the formation of MW grains. Further investigation was carried out to identify the parameters that distinguish perfect and MW grains grown in high-temperature versus those grown in low-solar-radiation conditions. As reported previously, the chalk phenotypes in the transverse section of the MW grains were quite different between environments: oval-shaped chalk for MW grains grown in low-solar-radiation condition and center chalk for MW grains grown in high-temperature condition. Grain hardness and amylopectin chain-length distribution did not explain the difference in MW grains between environments. MW grains subjected to high temperatures had a lower protein content without a consistent reduction in the single-grain weight, whereas those from the low-solar-radiation condition had a lower amylose content with a consistent reduction in the single-grain weight, when compared with perfect grains that developed in either environmental condition. Overall, our results suggest that MW grains are formed through different physiological mechanisms with altered starch and protein synthesis under high-temperature and low-solar-radiation conditions.

Abbreviations: BW: basal-white; DAH: days after heading; DP: degree of polymerization; MW; milky-white WB: white-back     

Gas chromatography–mass spectrometry associated global analysis of rice root exudates under aseptical conditions

Components of rice root exudates were surveyed by gas chromatography–mass spectrometry (GC-MS) and the effect of phosphate (P) starvation was investigated. Rice seedlings were aseptically grown in controlled environments under P-supplied (+P) or P-deficient (–P) conditions. Root exudates were collected from the culture solution 4 and 8 days after treatment (D4 and D8, respectively), which contain the first and second 4-day intervals. The collected solution was lyophilized and then eluted with methanol. In the present study, primary metabolites, such as sugars, amino acids, organic acids and fatty acids, were mainly targeted. After derivatization with methoxyamine hydrochloride and N-methyl-N-trifluoroacetamide, the samples were analyzed by GC-MS. Sugars and various amino acids (such as aspartic acid and l -isoleucine) were mainly detected and the components changed with the growth stage rather than the P content in the culture solution. The relative amount of sugars (such as glucose and fructose) and amino acids (such as aspartic acid and l -isoleucine) decreased in the D8 samples. Of the 78 detected compounds, orthogonal partial least-squares discrimination analysis (O-PLS-DA) showed that four compounds were related to the P content of the nutrient solution and 58 were related to the sampling date (days after treatment). The results suggest that the physiological change during seedling development was unexpectedly large and that the response to the environment was rather small.     

Decomposition of soil organic carbon influenced by soil temperature and moisture in Andisol and Inceptisol paddy soils in a cold temperate region of Japan

Purpose

Understanding the effects of temperature and moisture on soil organic carbon (SOC) dynamics is crucial to predict the cycling of C in terrestrial ecosystems under a changing climate. For single rice cropping system, there are two contrasting phases of SOC decomposition in rice paddy soils: mineralization under aerobic conditions during the off-rice season and fermentation under anaerobic conditions during the growth season. This study aimed to investigate the effects of soil temperature and moisture on SOC decomposition under the aerobic and subsequently anaerobic conditions.

Materials and methods

Two Japanese paddy soils (Andisol and Inceptisol) were firstly incubated under four temperatures (±5, 5, 15, and 25°C) and two moisture levels (60 and 100% water-filled pore space (WFPS)) under aerobic conditions for 24 weeks. Then, these samples were incubated for 4 weeks at 30°C and under anaerobic conditions. Carbon dioxide (CO₂) and methane (CH₄) productions were measured during the two incubation stages to monitor the SOC decomposition dynamics. The temperature sensitivity of SOC was estimated by calculation of the Q₁₀ parameter.

Results and discussion

The total CO₂ production after the 24-week aerobic incubation was significantly higher in both soils for increasing soil temperature and moisture (P < 0.01). During the subsequent anaerobic incubation, total decomposed C (sum of CO₂ and CH₄ productions) was significantly lower in samples that had been aerobically incubated at higher temperatures (15 and 25°C). Moreover, CH₄ production was extremely low in all soil samples. Total decomposed C after the two incubation stages ranged from 256.8 to 1146.1 mg C kg^?1 in the Andisol and from 301.3 to 668.8 mg C kg^?1 in the Inceptisol. However, the ratios of total decomposed C to SOC ranged from 0.29 to 1.29% in the Andisol and from 2.21 to 4.91% in the Inceptisol.

Conclusions

Both aerobic and anaerobic decompositions of SOC in two paddy soils were significantly affected by soil temperature and moisture. Maintaining optimal soil temperature and medium moisture during the off-rice season might be an appropriate agricultural management to mitigate CH₄ emission in the following rice growth season. Although it is high in SOC content, Andisol has less biodegradable components compared to Inceptisol and this could be a probable reason for the distinct difference in temperature sensitivity of SOC decomposition between two paddy soils.