Comparison of S-RNase,RNase T1, T2, and A effects on growth inhibition and RNA degradation of in vitro-cultured pear pollen

To obtain the basic information on fruit set regulation, effects of several RNases including S-RNase on pollen tube growth and RNA degradation in the tube were studied in the pear. Purified S-RNase from the Japanese pear ‘Kosui’ (S₄S₅) predominantly inhibited the growth of ‘Kosui’ pollen tubes (self) in vitro at 0.28 unit μL⁻¹, but it inhibited ‘Chojuro’ (S₂S₃) pollen (cross) only slightly. The same unit of RNase T₁ (EC 3.1.27.3) clearly inhibited the pollen tube growth, but the action was significantly weaker than that of the S-RNase against the self-pollen. Inhibitory effect of RNase T₂ (EC 3.1.27.1) and RNase A (EC 3.1.27.5) was only slight. The proteins other than the S-RNase extracted from pear style did not have any inhibitory action, though they possessed RNase activity 3.8 times higher than S-RNase. Thus, RNases tested here could not substitute for the S-RNase in specific inhibition against the self-pollen tube growth. Total RNA degradation by each RNase occurred in the pollen tubes as following order; S-RNase (self) ≥T₁ > T₂ ≥ A > S-RNase (cross). Degradation degree of 28S and 18S rRNA was as follows; S-RNase (self) > A > T₁ > T₂ > S-RNase (cross). The degradation of 5.8S and 5S rRNA was; S-RNase (self) > S-RNase (cross) > A > T₂ > T_1. The degree of rRNA degradation was, thus, not always in parallel with the degree of pollen growth inhibition. The S-RNase may degrade not only rRNA but also mRNA essential for pollen tube growth, and may be specifically adapted to inhibit the growth of self-pollen tubes. Therefore, controlling S-RNase amount in the style will produce self-thinning cultivars efficiently, which are unnecessary not only for hand-pollination but fruit-thinning practices in the pear. Practically, cultivar with weak self-incompatibility and small amount of S-RNase, such as ‘Okusankichi’, may be an expecting candidate for breeding self-thinning cultivars.     

Phospholipase A<Subscript>1</Subscript> activity of crude enzyme extracted from the ovaries of skipjack tuna

The phospholipid class composition, fatty acid composition and phospholipase A₁ (PLA₁) activity from the ovaries of skipjack tuna were compared with those of six other species of marine fish. In the skipjack ovaries, the lysophosphatidylcholine (LPC) proportion for the phospholipid, the docosahexaenoic acid (DHA) percentage for the total fatty acids of the phospholipids and the PLA₁ activity of the crude enzyme were the highest among those of the seven species. The optimum pH and temperature for the PLA₁ activity of the crude enzyme from the skipjack ovaries were in the range of pH 6–7 and 20–30°C, respectively, and calcium ions were not required. As a substrate, phosphatidylcholine was more easily hydrolyzed than phosphatidylethanolamine by this enzyme, and the plasmalogen-type phospholipid was much lower than the acyl-type phospholipid. After a 6-h hydrolysis reaction of the purified phospholipid extracted from the mixed ovaries of skipjack and yellowfin tuna by this enzyme, the LPC ratio of the phospholipid increased from 20 to 72.6% and the percentage of DHA for the total fatty acids of the phospholipid also increased. Thus, skipjack ovaries might possibly be used as a source of PLA₁.     

Molecular detection of Anaplasma phagocytophilum in cattle and Ixodes persulcatus ticks

The tick-borne pathogen, Anaplasma phagocytophilum (A. phagocytophilum), the causative agent of human granulocytic anaplasmosis (HGA), is increasingly becoming a public health concern as an aetiological agent for emerging infectious disease. We found A. phagocytophilum infection in a pooled sample of field-collected Ixodes persulcatus (I. persulcatus) ticks from one district in Hokkaido, Japan. Thus, to further investigate the prevalence in field-collected ticks, we used PCR assays targeting the A. phagocytophilum gene encoding 44 kDa major outer membrane protein (p44) for screening of I. persulcatus ticks and samples from cattle from pastures. Out of the 281 I. persulcatus ticks, 20 (7.1%) were found to harbor A. phagocytophilum DNA. The infection rate for A. phagocytophilum in cattle was 3.4% (42/1251). In future studies, it will be necessary to investigate effects of the infection in order to understand its pathogenesis of A. phagocytophilum in domestic animals.     

梨花柱S糖蛋白对离体花粉萌发及花粉管生长的影响

应用CM和SP琼脂糖凝胶 (Sepharose)离子交换层析法从‘新水’梨花柱可溶性蛋白质中分离纯化出具有RNase活性的S糖蛋白 ,将其加入花粉培养基 3～ 12h ,新水花粉 (自交不亲和 )的萌发率及花粉管生长受到强烈抑制 ,当浓度为 1.2 5μg·μL- 1时 ,分别为对照的 6 5%和 38% ,低浓度 (0 .4 μg·μL- 1)抑制作用不明显 ;与新水杂交不亲和的‘幸水’花粉也出现同样的结果 ;而与其杂交亲和的‘长十郎’花粉萌发率不受影响 ,仅花粉管生长受到轻微的抑制 ,其长度为对照的 79%。不含S糖蛋白的花柱可溶性蛋白质对自花及异花的花粉萌发及花粉管生长均无影响。     

Biomass of a man-made forest of timber tree species in the humid tropics of West Java, Indonesia

Biomass of a mature man-made forest in West Java, Indonesia, was estimated to evaluate the carbon sequestration potential of plantation forest in the humid tropics. Twenty plots, each 0.25 ha in area and containing one to six planted species over 40 years of age and with closed canopies, were selected. Trunk dry mass was estimated from trunk diameter, tree height, and bulk density. Maximum trunk diameter (122 cm) was observed in a 46-year-old Khaya grandifoliola C. DC. tree, and the tallest tree (51 m) was a 46-year-old Shorea selanica (DC.) Blume. The largest trunk biomass (911 Mg ha⁻¹) was achieved in the plot composed of two Khaya spp. Among the plots composed of indigeneous Dipterocarpaceae species, the largest trunk biomass was 635 Mg ha⁻¹. These trunk biomasses were larger than those reported from primary rainforests in Southeast Asia (e.g., 403 Mg ha⁻¹ in East Kalimantan, 522 and 368 Mg ha⁻¹ in Peninsular Malaysia). The large biomass in this forest suggests that, given favorable conditions, man-made forests can accumulate the quantities of atmospheric carbon that were lost by the logging of primary forests in the humid tropics.     

Fructose inhibits pear pollen germination on agar medium without loss of viability

Pollen of Japanese pear (Pyrus pyrifolia Nakai) germinated well on agar medium containing 10% sucrose or glucose, but not on agar containing fructose. The inhibitory effect of fructose was dose-dependent. Sucrose enhanced pollen tube growth much more effectively than glucose. Addition of 5% fructose to 5% or 10% sucrose or glucose media suppressed germination completely. Ungerminated pollen, however, showed similar respiration rate and stainability against acetocarmine dye as germinated pollen. When pollen was transferred onto fructose medium after culturing it on glucose or sucrose medium for 1–2 h, germination was completely impeded. Reversely, pollen transferred to sucrose or glucose medium from fructose medium germinated at almost the same ratio as pollen on sucrose or glucose medium without transfer. Thus, pollen inhibition by fructose is reversible. Compared with uncultured pollen, cultured pollen contained less than half amount of total sugars, even if failed in germination on fructose medium. Germinated pollen on sucrose and glucose media contained sucrose and glucose, but ungerminated pollen on fructose medium contained only trace levels of these sugars, suggests that pollen on fructose medium predominantly uses sucrose and glucose as respiration substrates and cannot maintain the constant levels of these sugars. However, as pollen germination occurred on agar medium without any sugar, fructose may impede a physiological factor that triggers germination, and once the trigger is impeded, many physiological pathways including sugar biosynthesis may be blocked.     

Heinz body hemolytic anemia with eccentrocytosis from ingestion of Chinese chive (Allium tuberosum) and garlic (Allium sativum) in a dog

A 4-year-old, intact male miniature schnauzer was presented with anorexia. The dog had ingested some Chinese steamed dumplings 2 days before, which contained Chinese chive (Allium tuberosum) and garlic (Allium sativum). Hematological examinations revealed severe Heinz body hemolytic anemia with eccentrocytosis and an increased concentration of methemoglobin, which was thought to result from oxidative damage to erythrocytes by constituents in these Allium plants. In this case, eccentrocytosis was a hallmark finding and could be detected easily, suggesting that this hematological abnormality is useful in diagnosing Allium plant-induced hemolysis.