Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

BJ-HCC-20, a potential novel cancer-testis antigen.

In an effort to identify novel Cancer-Testis genes, we analyzed the sequence in the q26-28 region of human X chromosome by several on-line tools. The candidate sequences were then confirmed by experiments. We have obtained a novel Cancer-Testis gene, BJ-HCC-20. In vivo, it was found to have two isoforms. In samples of liver, colon, gastric and lung cancer tested, the expression frequency of BJ-HCC-20 is 25%, 17%, 21% and 15%, respectively. Full-length cDNAs of both BJ-HCC-20 isoforms were isolated and their gene structures and promoter regions were characterized. BJ-HCC-20 might have implications in theoretical and practical tumor biology.     

Occurrence of ceramide-glycanase in the earthworm, Lumbricus terrestris

We have detected the presence of ceramide-glycanase in the earthworm, Lumbricus terrestris. We have also devised a simple method for the preparation of this enzyme from the earthworm. This enzyme cleaved the linkage between the ceramide and the glycan chain in LacCer, GbOse3Cer, GbOse4Cer, GbOse5Cer, GM3, GM2, GM1 and GD1a. By using tritium-labeled GM2 as substrate, the optimum pH of this enzyme was found to be between pH 4 and 4.5. In the earthworm, the ceramide-glycanase was mainly found in the muscle. The intestine was found to contain a very low level of this enzyme. Because of their easy availability, earthworms should become a convenient source for the preparation of ceramide-glycanase.     

The study of binding of the virG gene product with the virD gene promotor region of the Agrobacterium tumefaciens Ti-plasmid C58

The 1.5 kb EcoRI--HindIII fragment of the pTiC58 containing the virD regulatory sequence demonstrates a constitutive promoter activity in E. coli background and an inducible one in agrobacterium. The virG gene was cloned in pTZ19R plasmid. To reveal the virG product--virD regulatory sequence interaction a few protein fractions of E. coli harbouring the obtained recombinant plasmid pTZ19G lysate were used. PAGE-retardation assay revealed the specific binding between the 1.5 kb DNA fragment containing 5'-end of virD and a separate protein fraction of the bacterial lysate.     

固定化酶的微环境效应—载体离子基团性质的影响

作者合成了阴离子型和阳离子型葡聚糖,以此为载体,用CNBr活化其剩余羟基,固定化了葡萄糖淀粉酶和葡萄糖异构酶。就离子型载体对固定化酶的蛋白载量、最适pH和热稳定性等的影响做了考察。发现固定化酶的蛋白载量不仅与载体的电性质有关,也与酶分子自身的电性质有关。当载体电性质与酶蛋白电性质相反时,固定化酶的蛋白载量增加,热稳定性提高、载体电性质与酶蛋白电性质相同时,固定化酶的蛋白载量不变或下降,其热稳定性不变。作者还发现当离子型载体孔度和体系缓冲液浓度一定时,酶分子能否进入多孔性载体内部,对其最适pH是否变化影响极大。若酶分子仅被连接在载体的外表层,其最适pH不发生变化,反之亦然。作者还观察到当多糖类载体引入氨基或羧基后,大大增强了其抵抗微生物侵蚀的能力。     

Characterization and chromosomal mapping of the gene encoding the cellular DNA binding protein ILF.

Recently we isolated a cellular DNA binding protein, designated interleukin enhancer binding factor (ILF), that binds to purine-rich regulatory motifs in both the HIV-1 LTR and the IL2 promoter. Further analysis of the ILF gene reveals the existence of two mRNA species, both of which encode proteins containing the recently described fork head DNA binding domain. Gel retardation analysis demonstrates that the portion of the ILF protein with homology to the fork head domain is sufficient to mediate DNA binding to a number of related purine-rich sequences. ILF mRNA is expressed constitutively in both lymphoid and nonlymphoid tissues. Chromosomal mapping localizes the ILF gene to human chromosome 17q25, which is a site of chromosomal translocations in some cases of human acute myelogous leukemias. These studies further characterize the structure of the cellular DNA binding protein ILF and may prove valuable in the molecular analysis of possible translocations affecting this gene.     

Topoisomerase II activity in a DNA double-strand break repair deficient Chinese hamster ovary cell line

Topoisomerase II activity was measured in wild-type, Chinese hamster ovary K1 cells, and in the DNA double-strand break repair deficient xrs-6 cell line. Total topoisomerase II activity in a high salt, nuclear extract was found to be the same in both cell lines, as measured by decatenation of kinetoplast DNA networks and catenation of plasmid pBR322 DNA. While at low drug concentrations m-AMSA-induced enzyme cutting of nuclear DNA was 25% less in xrs-6 cells, the frequency of DNA breaks at high concentrations of the drug, and thus the frequency of the topoisomerase II enzyme, was the same in both cell lines. Despite the presence of equivalent enzyme levels in both cell lines, the xrs-6 cell line was 3 times more sensitive to drug-induced cytotoxicity. These results may be due to the fact that, as with X-radiation-induced DNA damage, xrs-6 cells are deficient in the capacity to rejoin topoisomerase II-induced DNA double-strand breaks.     

Metabolism of [4-14C]estrone in hamster and rat hepatic and renal microsomes: species-, sex- and age-specific differences.

The metabolism of [4-14C]estrone (E1) was examined in liver and kidney microsomes of adult castrated male and ovariectomized female hamsters and rats and in neonatal and immature hamster renal microsomes. In castrated male hamster liver microsomes, E1 was metabolized extensively to six major metabolites; 15 beta-hydroxyestrone, 7 alpha-hydroxyestrone, 6 alpha-hydroxyestrone, 6 beta-hydroxyestrone, 2-hydroxyestrone, and delta(9,11)-dehydroestrone, and a nonpolar fraction. Six minor metabolites of E1 were also detected. In contrast, kidney microsomes derived from castrated male hamsters metabolized E1 to mainly 17 beta-estradiol, 2- and 4-hydroxyestrone, 6 alpha-hydroxyestrone, 6 beta-hydroxyestrone and one monohydroxyestradiol metabolite. However, 16 alpha-hydroxyestrone was not detected. A variable, but low amount of estriol was also found. Interestingly, the quantity of 2-hydroxyestrone found in kidney microsomes of the hamster represented 26% of the total amount of metabolites formed, whereas in liver microsomes, only 9% of the overall metabolism resulted in the formation of 2-hydroxyestrone. The ability of kidney microsomes of female ovariectomized hamsters and two different rat strains to metabolize E1 was 5.9- and 9.4-fold lower, respectively, compared to renal microsomes of male castrated hamsters. The onset of oxidative metabolism in newborn hamster kidneys during development was also assessed. The results indicate that the oxidative metabolism of [14C]E1 in renal microsomes of newborn hamsters was 20-fold less than in kidney microsomes of adult hamsters. While catechol E1 metabolites were essentially negligible in hamster kidneys of these ages, it was evident that the conversion of E1 to estradiol via 17 beta-hydroxysteroid dehydrogenase resembles levels seen in the adult animals. Between the age of one and two months, the male hamster kidney exhibited the capacity to metabolize E1 at levels seen in fully mature adult hamsters.     

Urea-induced transformation of native estrogen receptor and evidence for separate DNA-and ATP-binding sites

We have investigated the involvement of hydrophobic receptor domains during transformation of the native estrogen receptor to a form(s) with high affinity for immobilized DNA and ATP. In the presence of 6 M urea the intact estrogen-receptor complex was completely (greater than 90%, n = 12) transformed into a DNA-binding configuration but only partially (35-45%, n = 8) transformed into an ATP-binding state. Similar experiments performed with unliganded receptor preparations further distinguished the receptor's DNA and ATP binding properties. While the urea-induced increase in receptor affinity for DNA-agarose was estrogen-dependent, the urea-induced increase in affinity for ATP-agarose was steroid-independent. This is the first direct evidence that hydrophobic receptor domains may be involved in the steroid-dependent exposure of the DNA binding site. This event is partially reversible and suggests that electrostatic interactions alone may not be sufficient to accurately describe receptor recognition of specific DNA acceptor sites.     

Immunocytochemical diagnosis of acute leukemia with pleural involvement

Cytologic examination of the pleural effusion from a patient with acute leukemia, leukocytosis and bleeding revealed the presence of many leukemic cells, "lymphocytes" and erythrocytes. The significance of these cellular changes was investigated by simultaneous study of blood and effusion leukocytes by morphologic, cytochemical and immunochemical methods. Both the leukemic blasts and the "lymphocytes" in the effusion and the blood were found to be neoplastic and contained antigens characteristic of both myeloid cells (OKM-1) and lymphoblasts (C-ALLA, common acute lymphoblastic leukemia antigen). These results, when analyzed in the context of the clinical findings, were indicative of acute leukemia with pleural involvement. Such a clinically oriented approach may further enhance the potential of cytodiagnosis in patients with serous effusions.