Effect of apholate and hempa on nucleic acid and protein syntheses in the yellow-fever mosquito

The growth curve, nucleic acid and protein content of the various life stages of Aedes aegypti were studied. The larvae of this mosquito were treated with sterilizing doses of the chemosterilants apholate and hempa, and their effects on the above parameters were also investigated. The body-weight increased gradually in the earlier instars and showed a sharp rise from late-fourth instar to the pupa. Adults weighed less than the pupae. Females weighed more than the males. In the controls, DNA and RNA content generally followed the growth curve. RNA content was more than DNA up to the late-fourth instar and the ratio reversed in the later stages. Protein content also followed the growth curve except in adult female, where it was more than in the pupa. In general the treatment with the chemosterilants, apholate and hempa did not seem to alter RNA, DNA and protein content in the whole insect.

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Zusammenfassung Wachstumskurve, Nukleinsäure- und Eiweißgehalt verschiedener Entwicklungsstadien der Gelbfieber-Mücke, Aedes aegypti, wurden untersucht. Die Larven dieser Mücke wurden mit sterilisierenden Dosen der Chemosterilantia Apholate und Hempa behandelt und ihre Wirkungen auf die genannten Parameter geprüft. Das Körpergewicht nahm in den frühen Stadien allmählich zu und zeigte vom Ende des 4. Stadiums bis zur Puppe einen steilen Anstieg. Adulte wogen weniger als die Puppen, Weibchen mehr als Männchen. In den Kontrollen folgte der DNS- und RNS-Gehalt im allgemeinen der Wachstumskurve. Der RNS-Gehalt war bis zum späten 4. Stadium größer als der DNS-Gehalt, in den späteren Stadien kehrte sich das Verhältnis um. Der Eiweißgehalt folgte ebenfalls der Wachstumskurve mit Ausnahme bei den Weibchen, wo er höher war als in der Puppe. Im allgemeinen schien die Behandlung mit den Chemosterilantien Apholate und Hempa den RNS-, DNS- und Eiweißgehalt im ganzen Insekt nicht zu verändern.

     

Calcium regulation of growth and differentiation of normal human keratinocytes: modulation of differentiation competence by stages of growth and extracellular calcium

In this study we examined the different aspects of the pathway leading to the differentiation of keratinocytes as a function of time in culture and calcium concentration of the culture medium. Human neonatal foreskin keratinocytes were grown in a serum-free, defined medium containing 0.07, 1.2, or 2.4 mM calcium and assayed for the rate of growth and protein synthesis, involucrin content, transglutaminase activity, and cornified envelope formation at preconfluent, confluent, and postconfluent stages of growth. We observed that keratinocytes grown to postconfluence in all calcium concentrations showed an increased protein/DNA ratio and an increased rate of membrane-associated protein synthesis. Extracellular calcium concentrations did not have a clear influence on these parameters. However, preconfluent and confluent keratinocytes grown in 0.07 mM calcium showed markedly retarded differentiation at all steps, i.e., involucrin synthesis, transglutaminase activity, and cornified envelope formation. Within 1 week after achieving confluence, these keratinocytes began synthesizing involucrin and transglutaminase and developed the ability to form cornified envelopes. Cells grown in 1.2 and 2.4 mM calcium synthesized involucrin and transglutaminase prior to confluence and were fully competent to form cornified envelopes by confluence. Thus external calcium-regulated keratinocyte differentiation is not an all or none phenomenon, but rather it is the rate at which keratinocytes differentiate that is controlled by calcium. We conclude that either or both higher extracellular calcium concentration and the achievement of cell-cell contacts lead to a coordinate increase of at least two precursors--involucrin content and transglutaminase activity--required for cornified envelope formation. We speculate that a critical level of cytosolic calcium, achieved by increased extracellular calcium or by achievement of intercellular communication established by cell-cell contact, may trigger mechanisms required for initiation of keratinocyte differentiation.     

Sperm motility initiation factor is a minor component of the Pacific herring egg chorion

Polyclonal antibodies were generated to the 105 kDa herring sperm motility initiation factor (SMIF) and used to explore the role of SMIF in sperm-egg interaction. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting with SMIF antibodies, it was demonstrated that SMIF is present as a minor (4–7% of total chorion protein) component of the chorion. The major polypeptides in the chorion migrated at 117 kDa and in a grouping between 48–54 kDa, with other minor bands above and below. The only detectable glycosylated component was the 105 kDa band, which was resolved at two isoelectric points (8.22 and 8.31) after isoelectric focusing gel electrophoresis. Using antibodies to SMIF, fertilization was blocked, sperm motility was inhibited in vitro in the presence of solubilized SMIF and SMIF binding sites on sperm were localized. Lastly, SMIF was localized to the region of the herring egg that encircles the micropyle.     

Occurrence of airborne bacteria and pathogen indicators during land application of sewage sludge.

Glass impingers (AGI-30) were used at a commercial sludge application site to determine the levels of airborne bacteria and pathogen indicators. Even though heterotrophic bacteria averaged 10(5) CFU/m3, none of the sites showed the presence of Salmonella spp. or indicators such as fecal coliforms or coliphages. Indicators such as H2S producers and pathogenic clostridia were present in locations having significant physical agitation of the sludge material. PCR-based ribotyping using the 16S-23S interspacer region is a promising method to identify the genetic relatedness and origins of airborne clostridia.     

Loss of DNA repair mechanisms in cardiac myocytes induce dilated cardiomyopathy

Cardiomyopathy is a progressive disease of the myocardium leading to impaired contractility. Genotoxic cancer therapies are known to be potent drivers of cardiomyopathy, whereas causes of spontaneous disease remain unclear. To test the hypothesis that endogenous genotoxic stress contributes to cardiomyopathy, we deleted the DNA repair gene Ercc1 specifically in striated muscle using a floxed allele of Ercc1 and mice expressing Cre under control of the muscle-specific creatinine kinase (Ckmm) promoter or depleted systemically (Ercc1^−/D mice). Ckmm-Cre^+/−;Ercc1^−/fl mice expired suddenly of heart disease by 7 months of age. As young adults, the hearts of Ckmm-Cre^+/−;Ercc1^−/fl mice were structurally and functionally normal, but by 6-months-of-age, there was significant ventricular dilation, wall thinning, interstitial fibrosis, and systolic dysfunction indicative of dilated cardiomyopathy. Cardiac tissue from the tissue-specific or systemic model showed increased apoptosis and cardiac myocytes from Ckmm-Cre^+/-;Ercc1^−/fl mice were hypersensitive to genotoxins, resulting in apoptosis. p53 levels and target gene expression, including several antioxidants, were increased in cardiac tissue from Ckmm-Cre^+/−;Ercc1^−/fl and Ercc1^−/D mice. Despite this, cardiac tissue from older mutant mice showed evidence of increased oxidative stress. Genetic or pharmacologic inhibition of p53 attenuated apoptosis and improved disease markers. Similarly, overexpression of mitochondrial-targeted catalase improved disease markers. Together, these data support the conclusion that DNA damage produced endogenously can drive cardiac disease and does so mechanistically via chronic activation of p53 and increased oxidative stress, driving cardiac myocyte apoptosis, dilated cardiomyopathy, and sudden death.     

The effect of thyrotropin releasing hormone and morphine on gastrointestinal transit

The effect of thyrotropin releasing hormone (TRH) alone and in combination with morphine on the gastrointestinal transit was investigated by using the charcoal meal test in mice. The intraperitoneal (IP) administration of TRH decreased the transit when given in a dose of 1.0 mg/kg 10 min prior to the meal. The intracerebroventricular (ICV) administration of TRH (10 μg/mouse) also inhibited the transit when given just prior to the charcoal meal. Subcutaneous (SC) administration of morphine (5, 10 and 20 mg/kg) inhibited gastrointestinal transit in a dose dependent manner. When TRH (1, 3 and 10 mg/kg, IP as well as 0.3 μg, ICV) which had no effect on the transit by itself was combined with morphine (10 mg/kg, SC), an enhancement in the inhibition of the transit was observed. TRH-induced inhibition of the transit was antagonized by naloxone (0.1 mg/kg, SC). It is concluded that TRH inhibits gastrointestinal transit in the mouse possibly via the opiate receptor system.     

Modification of an essential arginine of carbamate kinase

Carbamate kinase from Streptococcus faecalis is inactivated by butanedione in borate buffer, which implies the presence of an essential arginine at the active site of the enzyme. The inactivation reaction is first order in [butanedione] and a replot of the inactivation rate data infers that one arginine is modified. The enzyme is protected against inactivation by ADP, ATP, the metal-nucleotides and carbamyl phosphate but not by carbamate. Amino acid analyses reveal that one of three arginines is modified by butanedione in the absence of protecting agents, and the binding of ADP to the enzyme prevents modification. Thus, analysis of the data suggest that (i) substrate binding to arginine and (ii) protein conformational changes at the active site are responsible for protection of an essential arginine against modification by butanedione.