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.     

N-Deacetylation of 2-acetamido-2-deoxy-hexosecontaining oligosaccharides and polysaccharides by calcium in liquid ammonia

N-Deacetylation of 2-acetamido-2-deoxy-hexose residues is accomplished in liquid ammonia containing calcium. Oligosaccharides, lacto-N-fucopentaose II and lacto-N-difucohexaose I, containing 3,4-disubstitutedN-acetylhexosamine residues are quantitativelyN-deacetylated. When applied to polysaccharides, however, only partialN-deacetylation was achieved.Author for correspondence. AXRD     

Identification of thetrans-stilbene oxide-active glutathione transferase in human mononuclear leukocytes and in liver as GST1

A glutathione transferase from human mononuclear leukocytes with a high activity towardtrans-stilbene oxide (GT-tSBO) has been studied in liver and blood from fetus and adults and in blood from neonates. Using starch gel electrophoresis, different phenotypes of GST1 have been determined, GST1 0, GST1 1, and GST1 2. As judged from activity measurements and the fact that only those individuals who express the null allele of GST1, the GST1 0, which has a low activity towardtrans-stilbene oxide, it is concluded that the hepatic transferase GST1 is identical to GT-tSBO, as well as to hepatic transferase μ. In addition, it has been shown that the different genotypes of GST1 1 (GST1 1-1, GST1 1-0) and GST1 2 (GST1 2-2, GST1 2-0) can be separated by measuring the GT-tSBO activity in whole blood from the same individual. It is also demonstrated that GT-tSBO activity is much lower in fetal liver, approximately 10 times, compared with adult liver, while this activity seems to be unchanged in the blood from fetus and adults, as well as in neonates.     

Loss of CpG dinucleotides from DNA. VI. Methylation of mitochondrial and chloroplast genes

From nucleotide sequences of mitochondrial and chloroplast genes the probable frequency of the CpG----TpG + CpA substitutions was determined. These substitutions may indicate the level of prior DNA methylation. It was found that the level of this methylation is significantly lower in mitochondrial DNA (mtDNA) and chloroplast DNA (chDNA) than in nuclear DNA (nDNA) of the same species. The species (taxon) specificity of mtDNA and chDNA methylation was revealed. A correlation was found between the level of CpG methylation in nDNA, and mtDNA and chDNA in different organisms. It is shown that cytosine residues in CpG were not subjected to significant methylation in the fungi and invertebrate mtDNA and also in the algae chDNA. In contrast, the vertebrate mtDNA bears the impress of CpG-supression, which is confirmed by direct data on methylation of these DNA. Here the first data on the possible enzymatic methylation of the plant mtDNA and chDNA were obtained. It was shown that the degree of CpG-suppression in the 5S rRNA nuclear genes of lower and higher plants is significantly higher in the chloroplast genes of 4,5S and 5S rRNA. From data on pea chDNA hydrolysis with MspI and HpaII it was established that in CCGG sequences this DNA is not methylated. The role of DNA methylation in increasing the mutation rate and in accelerating the evolutionary rates of vertebrate mtDNA is discussed.     

The effect of estradiol valerate on follicular dynamics and superovulatory response in cows with Syncro-Mate-B implants

Two experiments were designed to evaluate the effect of estradiol valerate on follicular dynamics and superovulatory response in cows with Syncro-Mate-B (SMB)implants. In Experiment 1, 5 mg estradiol valerate (E(2)), injected at the same time as superstimulation treatments were initiated, resulted in fewer corpora lutea (CL), ova/embryos collected and fertilized ova (P<0.05) than if E(2) was administered with the SMB implant 7 days earlier. In Experiment 2, 31 beef cows and 26 Holstein cows were placed in one of four treatment groups. Group I (control) cows were superstimulated on Day 9 (estrus=Day 0). On Day 2, cows in Groups II, III, and IV received SMB and cows in Group III received E(2). On Day 9, cows in Group IV received E(2), and all cows were superstimulated with Folltropin. The number of CL did not differ (P>0.19) among groups. However, there were more follicles < 10 mm and fewer fertilized ova and transferable embryos (P<0.02) in Group IV cows. Ovarian ultrasonography revealed that the diameter of the largest follicle in Group III cows declined from Day 2 to Day 7 and subsequently increased until Day 13. In contrast, Groups I, II and IV were characterized by apparently linear growth between Days 2 and 13. Differences (P<0.05) were detected between Days 5 and 9. Mean diameter of the largest follicle was smaller for cows in Group III than for the remaining groups on Day 9. It was concluded that SMB did not adversely affect superovulatory response and that E(2) administration resulted in atresia of the antral follicles in the cows with SMB implants.     

Vitamin E Status of Healthy Swedish Cattle*

Using high pressure liquid chromatography the serum concentration of vitamin E was measured in dairy cows fed either hay or silage as their main roughage, in calves fed milk-replacer, and in young intensively fed bulls. The concentrates fed to the cows, calves and bulls were supplemented with 5–10, 25 and 5–10 mg DL-α-tocopheryl acetate per kg, respectively, and the milk-replacer for the calves was supplemented with 50 mg DL-α-tooopheryl acetate per kg powder. Cows fed silage as their main roughage had higher serum vitamin E concentrations ( $${\rm{\bar x}}$$ : 3.8–5.2 mg/l) than cows fed only hay ( $${\rm{\bar x}}$$ : 2.5–4.1 mg/1). Lactating cows had higher vitamin E concentrations than dry cows ( $${\rm{\bar x}}$$ : 4.1–5.2 and 2.5–3.8 mg/l, respectively) and calves and bulls had much lower vitamin E concentrations ( $${\rm{\bar x}}$$ : 1.4 and 1.2 mg/l, respectively) than cows. Thirty per cent of the calves and 41 % of the bulls had serum vitamin E concentrations less than 1.0 mg/l, suggesting that in these animals the conventional level of supplementation of feeds with DL-α-tocopheryl acetate in Sweden is probably inadequate for the prevention of nutritional muscular degeneration and other negative effects.     

The distribution and interconversion of ammonium and nitrate in the Skallingen salt marsh (Denmark) and their exchange with the adjacent coastal water

The potential nitrogen sources for the primary production in the intertidal area are nitrogen compounds obtained from mineralization in the sediment and the water column, nitrogen fixation, outflow from rivers and groundwater seeping from the mainland. The available inorganic nitrogen in the adjacent coastal waters decreases from 50–80 μmol NO₃ ^-/l and 6–15 μmol NH₄ ⁺/l in early spring to ca one tenth during the growing season. In the sediment of the tidal flats available ammonia and nitrate vary between 50 and 100 μmol/1 pw. In the salt marsh available ammonia increases from 200–300 nmol NH₄ ⁺/g fwt to approximately double the amount, and the available nitrate varies from 100–300 nmol NO₃ ^-/g fwt (250–750 μmol NO₃ ^-/l pw) to ca one third during the growing season. The exchange of NH₄ ⁺, NO₂ ^- and NO₃ ^- across the sediment water interface has been estimated during tidal cycles under light and dark conditions on the tidal flats. The flux of nitrogen was dependent on the flora and fauna as well as the time of the year. The tidal activity, frequency and length of inundation are considered the driving force in a two-way process between salt marshes and adjacent coastal waters. The role of marsh sediment, tidal water and sediments of the tidal flats as sites of accumulation, consumption and remineralization of organic matter is emphasized. The possible exchange of ammonia and nitrate between the salt marsh and the different compartments of the tidal water is discussed.     

Extractive bioconversion in aqueous two-phase systems

Summary The transformation of hydrocortisone to prednisolone was studied in aqueous two-phase systems, as a model for the extractive bioconversion of fine chemicals. The bacterium, Arthrobacter simplex, was able to grow in the two-phase system and the cells could be revitalized after a period of use. Use of aqueous two-phase systems made it possible to operate the reaction at higher substrate concentrations than in pure buffer solution. An adsorptive method to remove the product from the top phase was tested and shown to be both efficient and compatible with the overall process. In order to reduce the costs of operation in aqueous two-phase systems, a cheaper starch-based polymer, Reppal-PES, was successfully used as a substitute for dextran.Dedicated to Professor Dr. Georg Manecke on the occasion of his 70th birthday     

Lipid pattern and Na+−K+-dependent adenosine triphosphatase activity in the salt gland of duck before and after adaptation to hypertonic saline

Summary Ducks (Anas platyrhynchos) were fed hypertonic saline for eight days, resulting in an activation and hypertrophy of the salt gland. The Na⁺–K⁺-dependent adenosine triphosphatase, an enzyme generally assumed to be part of the active Na transport system, increased its specific activity by about 200% during this activation. Sulfatides, the major glycolipids of the salt gland, increased their concentration to the same extent. Cholesterol, cerebrosides, and six phospholipid classes showed an increase of 20–80%.A preliminary report on this work was given at the Second International Meeting of the International Society for Neurochemistry, Milan, September 1–5, 1969, and at the XIIIth International Conference on the Biochemistry of Lipids, Athens, September 7–12, 1969.     

Microdensitometer system for microradiography

Summary A microdensitometer system for point measurements in areas down to a few square micrometers is described. The detector system is connected to an integrating digital voltmeter, constituting a very sensitive system. The digital output signals and a digital identification are registered on a recorder and on a tape punch, thus facilitating computer analysis.The precision of the equipment varied from 1.1 per cent, for low signal levels, to 0.3 percent for the highest signal levels. Stray light, the only important source of systematic errors, was found to influence the output signal level. Concerning determinations of the densities, however, a variation of the order of 1 per cent was only obtained for small areas with densities differing from that of the background.