Tipula iridescent virus infection in the developmental stages of Tipula oleracea

Tipula iridescent virus (TIV) is infective to all four larval instars, pupae, and adults of both sexes of Tipula oleracea, and iridescence has been observed in infected insects at all these stages. Third- and fourth-instar larvae were more resistant to ingested TIV than first and second instars. When TIV was injected into the hemocoel, the results suggested a possible decrease in resistance from the third larval instar to the pupa. Incubation periods (times from injection of TIV to appearance of iridescence) were significantly shorter in older fourth-instar larvae than in younger fourth-instar or thirdinstar larvae, but variability in incubation period was significantly greater in younger fourth-instar larvae than in the other two stages. Many insects which were inoculated with TIV in one stage developed iridescence and died in later stages. The amounts of infective TIV in two infected adults were estimated.     

Susceptibility of the leatherjackets Tipula oleracea and T. paludosa to soil flooding

A relation was found between temperature and the survival of larvae of Tipula oleracea and T. paludosa when submerged in tap water alone or on turf growing on a sandy loam flooded with still or disturbed water (experiments with soil always starting with freshly flooded soil). Larvae under water alone usually survived until they starved, whereas larvae submerged on soil died in a relatively short time. The periods of survival at a depth of 25 mm were the same for both large and small larvae of either species at any one temperature. The regression of log.-log. survival time on temperature was a straight line, mean arithmetic values ranging from about 5 h at 20 °C to 122 h at 0 °C. Survival times at 25 mm were not increased by disturbing the water and the times at greater depths were no different, providing the water was still. If the water was regularly disturbed then the greater the depth the longer the survival time at any one temperature. Survival times in deoxygenated water indicated that lethal conditions may not be entirely due to deoxygenation of the water.     

Differentiation between larvae of Tipula paludosa and Tipula oleracea (Diptera: Tipulidae) using isoelectric focusing, and their occurrence in grassland in northern Britain

Thin layer agarose isoelectric focusing (IEF) was used to separate proteins from the larvae of Tipula oleracea Linnaeus and Tipula paludosa Meigen (Diptera, Nematocera). Silver staining revealed protein banding patterns which consistently distinguished these two species at any stage in their life cycles. Within the pH range 5–6 Tipula paludosa contained one major protein band and T. oleracea two bands, with the pI value of the T. paludosa protein being slightly higher than those of T. oleracea. The IEF method is particularly useful for the larval stages of these species because they are often visually inseparable. Leather jackets obtained during a survey of Northern Ireland and north-eastern and western Scotland were tested to determine the distribution and frequency of these species occurring in grassland. In each area surveyed T. paludosa predominated with only one field in Northern Ireland and north-eastern Scotland found to contain T. oleracea. In western Scotland T. oleracea occurred in five fields each year of the survey, and was locally abundant on the Isle of Bute in the 1990/91 survey making up 15% of the total larvae tested.     

The incidence of Rasajeyna nannyla in Tipula paludosa and Tipula vittata at two sites in Northumberland,England

Rasajeyna nannyla was an established pathogen at the two sample sites, and under the relatively constant conditions during two seasons, there was little change in the incidence of this pathogen. The incidence of R. nannyla was higher in Tipula vittata, a leatherjacket inhabiting damp regions of the sample sites, than in T. paludosa which inhabits drier regions. Monthly fluctuations of the level of R. nannyla in leatherjackets were not related to monthly variations in temperature. The incidence of R. nannyla in T. paludosa as a function of temperature is a significant positive slope, whereas the incidence of R. nannyla in T. vittata as a function of temperature is a significant negative slope.     

Metabolic changes in diseased insects. IV. Radioautographic studies on protein changes in nuclear polyhedrosis, densonucleosis, and Tipula iridescent virus infections

Changes in glutamic acid, leucine, arginine, and tyrosine in Lepidoptera and Hymenoptera tissues infected with nuclear polyhedrosis (NPV), densonucleosis (DNV), or Tipula iridescent (TIV) viruses were studied by radioautography with a view to determining the effect of the viruses on protein metabolism.     

Metabolic DNA in Spinach Stems in Connexion with Ageing

IF DNA is stable it ought to be synthesized only in cells preparing to divide, or during polyploidization or repair. Our results, however, suggest that the DNA synthesized in differentiated cells has a metabolic turnover, related to cell ageing¹. We call this DNA “metabolic”.     

Metabolic DNA in the hepatocyte nuclei in newborn rats.

The behaviour in time of labelled nuclear DNA in the hepatocytes of newborn rats was studied using autoradiographic and biochemical techniques in two groups of experiments. In the first group H-3-thymidine was injected to the mothers at the 16th day of pregnancy and the amount of labelled DNA was evaluated in the newborns after delivery. In the second group H-3-thymidine was injected to the newborns two hours after birth and the labelled DNA was studied at the same time intervals as the first group. The amount of labelled thymidine incorporated into the first group of animals remains constant for the first three days of life, thereafter a reduction in specific activity of DNA is observed concomitant with an increase of the percentage of labelled nuclei and a decrease of the number of grains per nucleus. These results show that mitotic divisions, which are absent during the first three days of life, take place between the third and sixth days of life. The decrease of the specific activity is therefore due to dilution and not to loss of labelled DNA. In the second group of experiments the DNA labelled with H-3-thymidine shows a decrease by about 30--40% per day during the first three days of life accompanied by a decrease in the number of grains per nucleus without changes in the percentage of labelled nuclei. These data show that DNA synthesized during the first day after birth is metabolically unstable, unlike that synthesized during foetal life.     

Microspectrofluorometric Measurement of Chloroplast DNA in Dividing and Expanding Leaf Cells of Spinacia oleracea

Absolute DNA amounts of individual chloroplasts from mesophyll and epidermal cells of developing spinach leaves were measured by microspectrofluorometry using the DNA-specific stain, 4,6-diamidino-2-phenyl indole, and the bacterium, Pediococcus damnosus, as an internal standard. Values obtained by this method showed that DNA amounts of individual chloroplasts from mesophyll cells fell within a normal distribution curve, although mean DNA amounts changed during leaf development and also differed from the levels in epidermal chloroplasts. There was no evidence in the data of plastids containing either the high or low levels of DNA which would be indicative of discontinuous polyploidy of plastids, or of division occurring in only a small subpopulation of chloroplasts. By contrast, the distribution of nuclear DNA amounts in the same leaf tissues in which cell division was known to be occurring showed a clear bimodal distribution. We consider that the distribution of chloroplast DNA in the plastid population shows that there is no S-phase of chloroplast DNA synthesis, all chloroplasts in the population in young leaf cells synthesize DNA, and all chloroplasts divide.     

The effect of soil flooding on the survival and development of the eggs of Tipula oleracea L. and T.paludosa Meigen (Diptera: Tipulidae)

A comparison is made of the survival and development of eggs of Tipula oleracea and T.paludosa, at certain temperatures, under water only or under water standing over soil. The significance the activity of the soil microflora and mechanical disturbance of the water is discussed.     

Metabolic rate and directional nucleotide substitution in animal mitochondrial DNA

There is marked heterogeneity of nucleotide composition in mitochondrial DNA across divergent animals. Differences in nucleotide composition presumably reflect differences in directional nucleotide substitution for A+T or G+C nucleotides. In mitochondrial DNA, there is A+T directional nucleotide substitution in most (if not all) animals surveyed, and the magnitude of directional A+T nucleotide substitution differs greatly within and among groups. Differences in directional nucleotide substitution among lineages of mammals can be explained by changes in metabolic physiology. This relationship is thought to be mediated by the effect of oxygen radicals because these toxic compounds are by-products of aerobic metabolism and are known mutagens. Association between metabolism and nucleotide composition provides additional evidence in favor of the hypothesis that rates and patterns of nucleotide substitution in mitochondrial DNA can be influenced by factors that impinge on rates of endogenous DNA damage.      

The Role of Mitochondrial DNA ORIB Polymorphism in Metabolic Syndrome

The development of the metabolic syndrome (MS) involves many genes. Certain evidence exists in the literature on the association of polymorphism in the mitochondrial DNA (mtDNA) oriB site, also known as the polycytosine pathway, with the development of insulin resistance, type 2 diabetes mellitus (T2DM) and other metabolic disorders in various ethnic populations. It is suggested that certain polymorphisms at this site are associated with mtDNA copy number in the cell. In this study, using capillary sequencing, we have identified various allelic variants of the mtDNA oriB site in patients with MS (n = 106) and conditionally healthy donors (n = 71). The mtDNA copy number in blood leukocytes was determined by the droplet digital polymerase chain reaction (ddPCR). It has been shown that the variant of the continuous polycytosine tract is significantly more frequent in MS patients with T2DM (p < 0.01). In general, the mtDNA copy number of blood leukocytes was lower in MS patients than in controls. We did not find any correlations between the oriB site variability and the mtDNA copy number.     

Die Chromosomen von Tipula paludosa Meig. in Eibildung und Spermatogenese

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