Long-term growth analyses of Japanese cedar trees in a plantation: neighborhood competition and persistence of initial growth deviations

The individual growth of tree diameter at breast height (dbh) is analyzed in an even-aged plantation of Cryptomeria japonica from stand age of 45 to 94 years, to examine how the growth of individual trees has been affected by the changes in spacing resulting from thinning operations. At any age, a significant proportion (0.37–0.46) of the variation in dbh growth during a 5–11-year period was explained by dbh at the beginning of the period, probably due to greater leaf mass of larger trees. Next, either one-sided or two-sided competition was added to the model, by calculating the basal area (BA) of neighboring trees around each tree within a given radius or BA for trees having larger dbh than the focal tree within the radius. After preliminary analyses, a radius of 8 m was selected as the critical range for tree competition. Although both types of competition explained a significant proportion (0.09–0.43) of growth variation, one-sided competition was not significant at ages greater than 54 years. Based on the model at 45 years of age, the initial deviation of growth rate for each tree from the predicted rate was calculated and added to the models as a third variable. This raised the coefficient of determination up to 0.50–0.74. These findings have practical significance for forest plantation management, particularly for controlling the growth of standing trees via thinning, to produce high-quality timber in the future.     

Novel prediction method of beer foam stability using protein Z, barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and yeast thioredoxin

Foam stability is an important quality trait of beer. Our previous results of two-dimensional gel electrophoresis (2DE) analyses of beer proteins implied a relationship between barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and beer foam stability as judged by the NIBEM-T analyzer. To develop a novel prediction method of beer foam stability under different conditions of barley cultivar and malt modification, multiple linear regression analysis was applied. The spot intensities of major beer proteins on 2DE gel were quantified and used as explanatory variables. The foam stabilities of 25 beer samples each brewed from malt with different malt modification in one of the three cultivars (cultivars A, B, and C) were explained by the spot intensities of BDAI-1 at the 5% significance level ( r = 0.421). Furthermore, two other major protein spots (b0 and b5) were observed on the 2DE gels of Japanese commercial beer samples with different foam stability. Then, multiple regression for foam stability was calculated using these three spot intensities as explanatory variables. As a result, 72.1% of the beer foam stability in 25 beer samples was explained by a novel multiple regression equation calculated using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. To verify the validity of the multiple regression equation and the explanatory variables, the beer foam stability in practical beer samples was analyzed. As a result, 81.5% of the beer foam stability in 10 Japanese commercial beer samples was also explained by using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. Mass spectrometry analyses followed by database searches revealed that protein spots b0 and b5 were identified as protein Z originated from barley and thioredoxin originated from yeast, respectively. These results confirm that BDAI-1 and protein Z are foam-positive factors and identify yeast thioredoxin as a possible novel foam-negative factor.     

Iron uptake in a bicarbonate-resistant cell line of tobacco

Abstract

In alkaline soils, plant growth is impaired mainly by high pH and high concentration of bicarbonates. The bicarbonate concentration increases the pH value, and causes deficiency of iron. A bicarbonate-resistant cell line (BR line) of tobacco (Nicotiana tabacum L. cv. Burley21) was selected by adding excess bicarbonate ions (20 mmol L^?1) to the culture medium. The pH of the medium was buffered 8.0 to 8.3. Under these conditions, about 80% of iron in the medium became insoluble. However, under such conditions, the BR line grew well. In this report, we examined some characteristics of the growth and iron uptake in the BR line under iron-deficient (i.e. high pH or no-iron) condition. At pH 5.8, the Fe³⁺ reduction activity was not significantly different between the non-selected line and the BR line. At pH 8.0, however, the Fe³⁺ reduction activity of the BR line was higher than that of the non-selected line. In no-iron condition, the growth of the non-selected line was markedly reduced after 2 weeks, while the BR line was not affected. The content of malic acid in both lines increased with the medium pH, and the content in the BR line was higher than that in the non-selected line. The BR line was able to adapt to the conditions, which restricted iron uptake, such as high bicarbonate concentration, high pH, and low iron conditions. The high ability of Fe³⁺ reduction was maintained at even high pH conditions. Further, the BR line may be able to improve the utilization of iron in the cells.     

Involvement of mammalian Mus81 in genome integrity and tumor suppression

Mus81-Eme1 endonuclease has been implicated in the rescue of stalled replication forks and the resolution of meiotic recombination intermediates in yeast. We used gene targeting to study the physiological requirements of Mus81 in mammals. Mus81-/- mice are viable and fertile, which indicates that mammalian Mus81 is not essential for recombination processes associated with meiosis. Mus81-deficient mice and cells were hypersensitive to the DNA cross-linking agent mitomycin C but not to gamma-irradiation. Remarkably, both homozygous Mus81-/- and heterozygous Mus81+/- mice exhibited a similar susceptibility to spontaneous chromosomal damage and a profound and equivalent predisposition to lymphomas and other cancers. These studies demonstrate a critical role for the proper biallelic expression of the mammalian Mus81 in the maintenance of genomic integrity and tumor suppression.     

Does future climate change facilitate expansion of evergreen broad-leaved tree species in the human-disturbed landscape of the Korean Peninsula? Implication for monitoring design of the impact assessment

To quantitatively assess future change of evergreen broad-leaved tree species’ distributions in human-disturbed landscapes of the Korean Peninsula under climate change, potential habitats (PHs) were projected for four important evergreen broad-leaved tree species (Quercus acuta, Castanopsis sieboldii, Machilus thunbergii, and Neolitsea sericea) by species distribution models (SDMs). The distribution data (presence/absence) of the target species in Korea and Japan were used as response variables for SDMs, and climatic data were used as explanatory variables. Three general circulation models under A2 emission scenarios were used as future climate scenarios for the years 2070–2099. Potential habitats masked by land-use data (PHLUs) were projected to assess the impact of anthropogenic activities. Highly accurate SDMs were obtained for all the target species. The current PHs were decreased to 21–35 % by the anthropogenic activities. Future PHLUs for all the target species were projected to increase by 2.0–18.5 times of current PHLUs. These results suggest that all the target species are applicable as indicator species for monitoring in the Korean Peninsula, even if anthropogenic effects are incorporated. Variation of the increasing rate was caused by the differences in the response to temperature changes. M. thunbergii responded sensitively to the increase of minimum temperature of coldest month and had a largest increase in PHLUs under future climate. Therefore, M. thunbergii is considered to be most appropriate species for monitoring the changes of horizontal distributions above all focal evergreen broad-leaved tree species.     

A size-structured model for a stock-recovery program for an exploited endemic fisheries resource

The size of harvests temporarily decreases following stock-recovery programs for overexploited resources. The process of stock recovery is quite uncertain, because of unknown life-history parameters, changes in environmental conditions, and human impact. To project future stock recovery, we considered a size-structured matrix model of a stock-recovery program, in which the minimum body size in the first harvest is increased. We applied some common concepts, including yield per recruitment, spawning per recruitment, and reproductive value, to a size-structured matrix model that incorporated economic discounting. The size-structured model predicted the following characteristics in stock-recovery processes: several years must pass for the harvest to increase, and the time-lag between the inception of the management program and the increase in the catch is caused by intergenerational momentum in demography. We also investigated the effects on the recovery process of temporal environmental fluctuations. We applied our model to a stock-recovery program of the corbiculid Seta clam (Corbicula sandai) in Lake Biwa, Japan.     

Caprine somatic cell nuclear transfer using in vivo matured oocytes collected by laparoscopic follicular aspiration

In vivo matured oocytes collected by laparoscopic follicular aspiration (LFA) from hormone treated female goats were used as recipient ooplasts for somatic cell nuclear transfer (SCNT). Japanese native (Shiba) goats were used as donor females and some donor females were used repeatedly (two or three times) at intervals of a few months. To induce synchronization of estrus, a sponge containing 0.5 g of progesterone was inserted into the vagina of each goat for 14 days. These animals were also treated with follicle stimulating hormone (FSH) in a series of 8 injections over 4 days. The first FSH injection was administered on the morning of day 9 of sponge insertion. On the morning of day 13, 50 µg of gonadotropin‐releasing hormone (GnRH) was injected into each animal. Twenty‐nine hours after GnRH injection, LFA was performed. After removal of cumulus cells, collected oocytes with the first polar body were selected and enucleated for nuclear transfer. Anterior pituitary cells isolated from an adult male Shiba goat were transfected with a DNA fragment containing the enhanced green flourescent protein gene and the puromycin resistance gene. A single donor cell was inserted into the perivitelline space of each enucleated oocyte and fusion was induced with one electric pulse of 20 V for 10 µs. The SCNT goat eggs were cultured in chemically defined medium at 38.5°C in 5% CO₂, 5% O₂, 90% N₂ for 9 days. By LFA, 396 oocytes were collected from a total of 30 females. After removal of cumulus cells, 64% of them extruded the first polar body. The percentage of SCNT goat eggs produced using in vivo matured oocytes which developed to the blastocyst stage (20–21%) was significantly higher (P < 0.05) than that produced with in vitro matured oocytes (3–8%).     

Development of transferred xenogeneic vole embryos in mouse uteri

An experimental model to study interspecific pregnancy using voles, Microtus arvalis, and green fluorescent protein gene‐induced transgenic mice is presented. Xenogeneic blastocysts from the vole were transferred into the uteri of pseudopregnant mice along with allogeneic blastocysts from green fluorescent protein gene‐induced transgenic mice. The uteri containing xeno‐allo combined transfers were examined from day 6 to 13 of gestation. Although the vole embryos implanted, the uteri containing vole embryos were smaller compared with those having allogeneic mouse embryos. On day 8, the uteri containing vole embryos hemorrhaged internally and no vole embryo was found in the pregnant uterus after day 11. Allogeneic mouse embryos developed normally despite the presence and abortion of the vole embryos. In uteri implanted with vole embryos, decidua were formed and numerous blood vessels were distributed around the embryo. Maternal blood cells infiltrated into the celomic cavity of the vole embryo through the discontinuous region of trophoblast. Periodic acid‐Schiff‐positive granulated metrial gland cells were remarkably increased in the decidual sites. These findings suggest that a disorder of embryo–maternal interaction might induce the appearance of numerous granulated metrial gland cells and rejection of the embryos.     

Nuclear transfer using a bovine mammary epithelial cell line (BMEC)

The developmental potential of nuclei from a bovine mammary epithelial cell line (BMEC) in nuclear transfer was investigated. For nuclear transfer donors, BMEC cells (passage 15) were cultured for 4–5 days after seeding at cell densities of 1.0 × 10⁵ cells/cm² (high‐density group) or 0.8 × 10⁴ cells/cm² (low‐density group). First, the effective electric stimulation for fusion of enucleated oocytes with BMEC cells was examined. Fusion rates reached maximum with two DC pulses of 30 V/150 µm for 20 µs in the high‐density group and with two DC pulses of 25 V/150 µm for 10 µs in the low‐density group. The fusion rate (37.5%) in the high‐density group was significantly (P < 0.005) lower than in the low‐density group (71.4%). Second, the in vitro developmental potential of nuclear transfer embryos derived from BMEC cells was examined. In the high‐density and low‐density groups, 18.8% and 24.1% of fused oocytes, respectively, developed to blastocyst stage. The results of this study indicate that nuclei from BMEC cells support the development of nuclear transfer embryos to the blastocyst stage and that the efficiency of oocyte–cell fusion is affected by the culture conditions of the donor BEMC cells before nuclear transfer.