评论：塑料结合模块促进聚对苯二甲酸乙二醇酯的酶法降解

塑料的大量生产和无节制的使用已造成严重的环境污染。为了减少塑料废物对环境的影响,近年来塑料酶法降解已成为国内外研究者关注的热点。例如,通过蛋白质工程策略提高塑料降解酶催化活性和热稳定性,进一步提高酶法降解的效率。另外,通过融合酶策略将塑料结合模块与塑料降解酶融合,也可以促进塑料降解。近期发表在期刊Chem Catalysis的一项研究表明,采用碳水化合物结合模块融合策略可以在低浓度(<10 wt%)的底物聚对苯二甲酸乙二醇酯[poly(ethylene terephthalate),PET]中提高塑料降解酶的活性。但是在高浓度底物(10 wt%−20 wt%)中,该策略无法提高PET的酶法降解。该项研究对于采用塑料结合模块促进酶法降解塑料具有重要的指导意义。     

Cigarette smoking during pregnancy lowers aromatase cytochrome P-450 in the human placenta

To clarify whether cigarette smoking during pregnancy causes an organic alteration in placental estrogen producing ability, we determined the catalytic activity of aromatase by the tritiated water assay, and tissue level of aromatase cytochrome P-450 (P-450_arom) by the specific enzyme-linked immunosorbent assay, in placental samples from nonsmokers and smokers. As pregnancy progressed, both aromatase activity and P-450_arom concentration increased in placentas from nonsmokers and smokers. However, the gradient of the increase was significantly less in heavy smokers (20 cigarettes a day) than in normal and moderate smokers (<20 cigarettes a day). At term, the mean aromatase activity and P-450_arom concentration in placentas from heavy smokers were significantly lower than in nonsmokers and moderate smokers, while aromatase activity per P-450_arom (turnover rate) and the mean placental weight were comparable among the three groups. In contrast, the ratio of aryl hydrocarbon hydroxylase activity to aromatase activity was higher in placentas from heavy smokers. Immunohistochemical studies showed that P-450_arom was localized in the cytoplasm of syncytiotrophoblasts of chorionic villi in placentas from both nonsmokers and smokers. These results suggest that the induction of placental P-450_arom during gestation is suppressed by maternal smoking, resulting in a reduction in estrogen producing ability, while placental xenobiotic P-450 is induced.     

ε-聚赖氨酸抑菌性能的研究进展

ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)是抑菌谱广泛的天然抑菌剂,由通过α-羧基与ε-氨基连接的25–35个赖氨酸聚合而成。ε-PL主要由白色链霉菌发酵生产所得,比化学生产更加高效和环保。ε-PL具有水溶性好、耐热和对环境无污染等特点,具有良好的应用前景。本文从发酵生产入手,着重综述了ε-PL对各种微生物抑菌性能、抑菌机制及抑菌机制模型的研究进展。推测ε-PL是通过对细胞膜的破坏而改变细胞的通透性,或者作用到细胞内引起活性氧(reactive oxygen species, ROS)胁迫而影响调节基因的表达,从而起到抑菌作用。根据这2种抑菌方式分别建立了相应的抑菌模型,即毡毯模型和ROS诱导细胞凋亡模型。本文可为ε-PL对微生物抑制性能的深入研究提供依据,同时也提出了ε-PL抑菌机制的新模型,为扩展ε-PL应用领域提供了一定的参考。     

广西防城港黑翅长脚鹬的繁殖行为

本研究于2021年3～9月,采用目标观察和全事件记录法,对广西防城港市钦州湾八路水湿地黑翅长脚鹬（Himantopus himantopus）的繁殖习性进行全过程观察记录。黑翅长脚鹬的栖息生境主要在盐田、虾塘和鱼塘,而巢主要分布在盐田生境。共发现39巢,雌雄共同营巢,按照主要巢材将其巢分为干草巢、碎石巢、泥皮巢和牛毛毡草巢4种;巢材包括禾本科（Gramineae）和莎草科（Cyperaceae）植物以及碎石、贝壳等;巢外径为（23.3±10.7）cm,巢内径为（11.2±1.9）cm,巢深为（1.6±0.5）cm,巢高为（6.5±4.3）cm(n=39);筑巢需（3±2）d(n=6)。窝卵数2～4枚,1～2 d产1枚卵,7 d内产完满窝卵（n=6）。雌雄均参与孵卵,雄性孵卵时间比雌性长,但二者差异不显著（P> 0.05）,雄性（8 550±245.9）min,雌性（7 530±263.3）min,孵卵期为（25±2）d(n=6)。育雏期（26±3）d(n=6),雌雄轮流育雏,育雏前、中期（雏鸟1～20d日龄）,雌性育雏时间比雄性长,是雄性的2倍,育雏后期（雏鸟大于20 d日龄）,...     

Characterization of antibody against human liver guanase by immunoblotting and immunohistochemical staining of human liver guanase by a direct labeling antibody-enzyme method

Human liver guanase was purified and a specific antibody against it was raised in rabbits. The antiserum formed a single precipitin line with human liver extract, and also completely inhibited the activity of the liver enzyme. An immunoblotting study showed that the antibody bound specifically to one band of protein with guanase activity and not to other proteins. Therefore, we concluded that this antiserum against the liver enzyme was suitable for use in immunohistochemical demonstration of guanase. In tissue sections, the immunohistochemical reaction with this antibody was positive in the same locations as the histochemical guanase reaction with DAB (3,3'-diaminobenzidine tetrahydrochloride).     

Chromosomes of Temnocephala minor,an ectosymbiotic turbellarian on Australian crayfish found in Kagoshima Prefecture,with karyological notes on exotic turbellarians found in Japan

Records of exotic turbellarian species found in Japan are reviewed from taxonomic and karyological viewpoints. Temnocephala minor Haswell, 1888, an ectocommensal on a freshwater crayfish of Australia, was found from culture ponds of Cherax tenuimanus (introduced from W. Australia) in Kagoshima Prefecture. T. minor had the chromosome number of 2x = 18 (2sm + 2m + 2m + 2sm + 2m + 2m + 2m + 2sm + 2m). The following 3 species of exotic freshwater triclads were recorded from tanks and ponds used for tropical fish culture: Dugesia austroasiatica Kawakatsu, 1985 (2x = 16), Dugesia tigrina (Girard, 1850) (2x = 16) and Rhodax? sp. (3x = 24; 3x = 24 &; 3x + 1LB + 1SB = 25 + 1SB). The following 3 species of exotic terrestrial triclads were recorded: Bipalium nobile Kawakatsu et Makino, 1982 (2x = 10), Bipalium kewense Moseley, 1878 (2x = 18), and Platydemus manokwari de Beauchamp, 1962 (n = 6, 2x = 12). An extensive occurrence of P. manokwari in the Southwest Islands of Japan may be due to an unexpected introduction of the animal in very recent years.     

Carcinogenesis in accessory sex organs of rats induced by 3,2′-dimethyl-4-aminobiphenyl: response to androgen deprivation

 It is generally accepted that early human prostate cancers reveal higher androgen dependency than do advanced ones. In the present study, we examined whether the animal model of prostate cancer has already lost androgen dependency at the early stages of carcinogenesis. At experimental week 46, androgen deprivation was induced in rats and the incidences of atypical hyperplasia and cancer were examined in the ventral, dorsolateral prostate, coagulating glands, and seminal vesicles. Androgen deprivation significantly lowered the incidence of atypical hyperplasia in all four organs. As for the incidence of cancer, no significant differences were observed in the coagulating glands and seminal vesicles. Regarding atypical hyperplasia, androgen deprivation significantly decreased the proliferative cell nuclear antigen labeling index in the coagulating gland and seminal vesicles. The presence of cancer was also decreased in the coagulating gland but not in the seminal vesicles. With control group specimens, more intense staining of androgen receptor was observed in atypical hyperplasias than in cancers. Compared with the atypical hyperplasias, the cancers revealed low androgen dependency at the early stages of carcinogenesis. The cancers in the seminal vesicles also revealed higher androgen independency than did those in the coagulating gland. Accepted: 6 May 1997     

广西和湖南的大瓣鱼科化石

详细记述了广西博白和湖南长沙中泥盆世的大瓣鱼科化石,依其特征建立一新属——广西瓣甲鱼Guangxipetalichthysgennov,该属头甲骨片排列型式与澳大利亚的Shearsbyaspis较为接近。同时讨论了鱼化石动物群及相关的地层问题。