Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.     

Cultivation of the retinal pigment epithelium in the cavity of the lentectomized eye of newts

A study was made of proliferative activity and transdifferentiation of the cells of retinal pigment epithelium (RPE) cultivated in the cavity of the lensectomized eye of adult newt. Implantation of the newt RPE together with vascular membrane and scleral coat resulted in the regeneration of retina. In this process the character of changes in the proliferative activity of RPE and differentiation of retinal cells were the same as in the regeneration of retina in situ. RPE implanted with the vascular membrane alone, despite a high level of proliferation during the first ten days of cultivation, no differentiated retina was formed. Possible causes of these differences are discussed, and the comparison is made of the data obtained with those on RPE cultivation in vitro. After lens removal, with RPE implants present in the eye cavity, in addition to the regenerated lens, 2-3 extra lenses and retina were formed from the cells of the inner layer of the recipient's dorsal iris. Also some cases were revealed of lens formation from the cells of ventral iris. With a complete detachment of the recipient's retina (an after-effect of transplantation) a second differentiated retina regenerated in situ from the recipient's RPE cells.     

Evidence for contact stimulation of growth of homologous cells in superinoculated cultures of chick embryo cells

The secondary cultures of chick embryo cells were suspended and transferred to homologous cell cultures. Cell adhesion and proliferation were studied in these superinoculated cultures. It was shown that added cells soon adhered to the underlying cell layer which results in a prompt increase in culture density followed by the activation of DNA synthesis and cell division. Stimulation of cell proliferation involved both cell subpopulations composing the superinoculated culture: cells seeded on the built-up cell layer and cells of the layer. The contact nature of added cell mitogenic action on overlaid cell proliferation was evidenced. The cell system described can be used to investigate the adhesive properties of the cell layer apical surface, the relationship between cell growth rate and culture density, and the contact stimulation of cell proliferation.     

Fibronectin distribution during the transdifferentiation and proliferation of eye cells after retinal detachment and removal of the crystalline lens in tritons

Expression of fibronectin (Fn) during eye tissue regeneration in the newt after retinal detachment and lens removal was studied by immunohistochemistry. Proliferation of cells involved in eye tissue regeneration was studied using autoradiography. Fn was detected around the cell membranes of undifferentiated proliferating and migrating cells in ciliary body of the iris and growth zone of the retina. Redistribution of Fn was observed in proliferating cells of the dorsal iris participating in lens regeneration. Fn appeared on the apical surface of proliferating redifferentiating pigment epithelium (PE) cells at the periphery of the eye and over the whole surface of proliferating PE cells in the central part of the eye. The Fn level in the Bruch's membrane decreased in the area of transdifferentiating cells detachment from PE layer (in the lower part of the eye) but continued to be stable in the area of PE cell redifferentiation (at the periphery of the eye). The role of Fn is discussed in relation to transdifferentiation, proliferation and migration of cells in the regenerating eye.     

康氏木霉纤维素酶系中C_x酶多分子型的分离纯化及某些性质

从康氐木霉(Trichoderma k(?)ningii)白色变异株As 3.4001的粗酶制剂中,获得了纤维素酶系中的一组C_x酶(C_(x1) C_(x2) C_(x3) C_(x4))。分离步骤包括Sephadex G-75凝胶过滤,DEAESephadex A-50离子交换层析,ConA-Sepharose亲合层析,SE-Sephadex C-50离子交换层析及聚丙烯酰胺凝胶电泳。C_(x1)与C_(x2)的分子量不同而所带电荷相同,它们的分子量各自为44,500和34,000。C_(x2)—C_(x4)的分子量相同而所带电荷不同。纯化的C_(x1)—C_(x4)经聚丙烯酰胺凝胶电泳鉴定为单带。比较它们对羧甲基纤维素钠(CMC-Na)的糖化力及液化力表明在作用方式的随机性上C_(x2)>C_(x3)>C_(x1)>C_(x4)。     

Biological activity of a new Soviet natural inducer, double-stranded RNA

Antiviral activity of a two-spiral RNA (ts RNA), a new natural interferon inductor was studied. It was shown that ts RNA extracted from a phage infected E. coli culture was an active inductor of interferon and resistance to infection with the forestspring encephalitis virus experimental animals. In experiments on 10-12 g mice ts RNA administered in a dose of 50 micrograms/mouse 6 hours after the infection induced up to 1280 units/ml of the serum interferon. When the inductor was administered repeatedly, the experimental animals developed hyporeactivity resulting in a marked decrease in interferon production after the 3rd subsequent injection. The most pronounced effect with respect to the forest-spring encephalitis virus was observed when the inductor was administered intraperitoneally in a dose of 20 micrograms/mouse 4 hours before the infection. The protective effect was less pronounced when the inductor was administered 24 and 48 hours before the infection. A two-fold administration of the inductor did not increase the antiviral effect. When the inductor was administered in a dose of 100 micrograms 14 days before the infection, the animals showed an increase in the nonspecific resistance to the infection resulting in a marked antiviral effect.     

The coagglutination reaction for detecting diphtheria toxin

High-titer antidiphtheria antitoxic rabbit serum has been obtained, and on the basis of this serum a coagglutinating diagnosticum has been developed. The sensitivity of the test has been found to depend on the content of antitoxic antibodies in the serum and on its purity. Diagnostica prepared from native serum containing 500 I. U./ml (a titer of 1:51, 200 in the passive hemagglutination test) permit the detection of 0.02-0.03 Lf/ml of diphtheria toxin. A decrease in antibody titer to 5-25 I. U./ml leads to a drop in sensitivity to 0.2-2 Lf/ml. The use of LgG fraction and pure antibodies increases the sensitivity of the test to 0.002-0.003 Lf/ml. The possibility of detecting toxin in Corynebacterium diphtheriae strains is shown.     

不同密度樟子松人工林土壤碳氮磷化学计量特征

以科尔沁沙地不同密度(490、750、1550、1930、2560株·hm-2)樟子松人工林(栽植于1980年)为研究对象,分析林分密度对土壤碳、氮、磷浓度及其计量比的影响,研究林分密度与土壤养分状况的关系。结果表明:随着樟子松林密度增加,各土层(0～10、10～20和20～40 cm)土壤有机碳、全氮、全磷浓度和C∶N呈先增加后降低趋势,而土壤有效磷浓度呈先降低后增加趋势。土壤有机碳浓度在490株·hm-2密度小于其他密度,而有效磷浓度大于其他密度;土壤C∶P和N∶P在2560株·hm-2密度显著大于其他密度。各密度樟子松林土壤有机碳、全氮、全磷和有效磷浓度在0～10 cm土层显著大于10～20和20～40cm土层,樟子松人工林土壤养分具有表聚性。通过典范对应分析发现,密度对樟子松林土壤养分影响的主要因子是土壤有机碳、全氮和全磷,且密度为1550株·hm-2时土壤有机碳、全氮、全磷和碱解氮浓度较高,而C∶P和N∶P较低。因此,当樟子松人工林密度为1550株·hm-2时,土壤养分浓度较高,林木生长较好,为最佳经营密度。     

土壤增温与氮添加对杉木幼苗细根径级根长分布的影响

通过在福建省三明市陈大林业国有林场内开展土壤增温(增温5 ℃、不增温)和氮添加(不添加、4、8 g N·m^-2·a^-1)的交互试验(共6个处理),研究土壤增温、氮添加及二者交互作用对杉木细根径级根长分布的影响,用扩展模型可很好地拟合6个处理的径级根长分布(R²=0.97).结果表明: 增温使杉木细根总根长变小,但对细根直径影响不显著;氮添加使杉木细根总根长和直径均变小;增温和氮添加的交互作用对细根总根长有显著影响,但对细根直径无显著影响.6个处理细根径级根长分布均能用极值函数模型较好地拟合(R²>0.98).相关分析显示,直径<1 mm细根的比根长与极值模型拟合参数c值呈显著负相关,实际总根长与极值模型拟合参数b呈显著正相关.增温和氮添加及其交互作用可以影响杉木细根形态特征;极值模型拟合各处理径级根长分布所得参数在一定程度上可以反映细根形态特征对环境条件变化的响应.