Multiple pyruvate decarboxylase genes in maize are induced by hypoxia

Two cDNA clones corresponding to anaerobically induced maize mRNAs were found to have homology to a previously identified maize pyruvate decarboxylase gene. DNA sequencing and RFLP mapping indicate that these cDNAs represent two additional maize pdc genes. Each of the clones is approximately 85% identical in predicted amino acid sequence to the other two. All three clones are induced by hypoxic stress, but with different levels and kinetics of induction.     

Local denaturation in DNA molecules

A two-dimensional anharmonic model, the so-called Toda-Lennard-Jones model, is considered in order to investigate the problems related to the lifetime of the open states precursors to full denaturation, in inhomogeneous ring-shaped DNA molecules. It is found that a transition from double-stranded to single-stranded DNA occurs locally around physiological temperature. Moreover, the presence of inhomogeneities enhances the hydrogen bond breaking.     

Cryptophytes: An emerging algal group in the rapidly changing Antarctic Peninsula marine environments

The western Antarctic Peninsula (WAP) is a climatically sensitive region where foundational changes at the basis of the food web have been recorded; cryptophytes are gradually outgrowing diatoms together with a decreased size spectrum of the phytoplankton community. Based on a 11-year (2008–2018) in-situ dataset, we demonstrate a strong coupling between biomass accumulation of cryptophytes, summer upper ocean stability, and the mixed layer depth. Our results shed light on the environmental conditions favoring the cryptophyte success in coastal regions of the WAP, especially during situations of shallower mixed layers associated with lower diatom biomass, which evidences a clear competition or niche segregation between diatoms and cryptophytes. We also unravel the cryptophyte photo-physiological niche by exploring its capacity to thrive under high light stress normally found in confined stratified upper layers. Such conditions are becoming more frequent in the Antarctic coastal waters and will likely have significant future implications at various levels of the marine food web. The competitive advantage of cryptophytes in environments with significant light level fluctuations was supported by laboratory experiments that revealed a high flexibility of cryptophytes to grow in different light conditions driven by a fast photo-regulating response. All tested physiological parameters support the hypothesis that cryptophytes are highly flexible regarding their growing light conditions and extremely efficient in rapidly photo-regulating changes to environmental light levels. This plasticity would give them a competitive advantage in exploiting an ecological niche where light levels fluctuate quickly. These findings provide new insights on niche separation between diatoms and cryptophytes, which is vital for a thorough understanding of the WAP marine ecosystem.     

Comparison of European and US biological indicators for ethylene oxide sterilization

Summary Biological indicators (BIs) are used to monitor ethylene oxide (EO) gas sterilization processes for medical devices. Several European and United States BIs for EO sterilization were evaluated for resistance according to both United States Pharmacopeia (USP) XXI and United Kingdom's (UK) tests for D-values. US BIs areB. subtilis var. niger spores on paper strips or disc carriers while European BIs use aluminum strips, quartz sand, or cotton yarn. Numerous BIs per run and runs per lot, as well as 2–3 different lots of BIs from each manufacturer, were examined. Both British and US BIs met their respective label claims for rates of inactivation when tested against British and USP EO test parameters, respectively. However, Danish BIs, on cotton yarn or quartz sand, were not inactivated following USP specifications during the exposure dwell times tested (600 mg L^–1 EO, 54°C, 60% RH, 0–110 min). The Danish BIs will require further testing in order for us to determine if theirB. subtilis spores are unusually resistant to EO or if the spore carrier substrates protect the spores from the sterilizing gas. In conclusion, the British and American BIs for EO sterilization are equivalent in resistance despite differences in carrier substrate, recovery conditions, calculation methods for D-values, and the labeled sterilization conditions for use.     

Life cycle of the microbivorous Antarctic Dry Valley nematode Scottnema lindsayae (Timm 1971)

The life cycle of the Antarctic Dry Valley soil nematode, Scottnema lindsayae (Timm 1971) was studied in laboratory culture at two temperatures, 10°C and 15°C. Soil yeast and bacteria isolated with the nematodes were used as the food source. The species reproduced sexually. The higher temperature had a negative effect on the life cycle. The number of eggs per female and the number of juveniles developing per female were greater at 10°C than at 15°C. Juveniles developed faster at 10°C and four juvenile stages were observed outside of the egg at both temperatures. The unusually long life cycle (218 d at 10°C) suggests that more than one austral summer may be required for successful completion. An increase in Dry Valley soil temperatures associated with potential global environmental change may have detrimental effects on soil nematodes.     

Degradation of the insecticide Hydramethylnon byPhanerochaete chrysosporium

The decomposition of the amidinohydrazone-type insecticide Hydramethylnon (HMN) by soil fungi has been investigated. A simple spectrophotometric method was developed for the estimation of HMN in soil and fungal culture media. HMN was found to be degraded in soil with a half life of 14 to 25 days.Degradation of HMN by the lignolytic fungus,Phanerochaete chrysosporium yielded two major breakdown products;p-(trifluoromethyl)-cinnamic acid (TFCA) andp-(trifluoromethyl)-benzoic acid (TFBA). TFCA was converted to TFBA which was subsequently metabolised via themeta-fission pathway. Fluoride release from HMN could not be detected.Abbreviations BzDAc benzene, dioxane, acetic acid (60: 36: 4) - DCM dichloroethane - DNPH 2,4-dinitro-phenylhydrazine - HMN Hydramethylnon - TDAc toluene, dioxane, acetic acid (90: 30: 1) - TFCA p-(trifluoromethyl)-cinnamic acid - TFBA p-(trifluoromethyl)-benzoic acid - TFP 1,5-bis(trifluoro-p-tolyl)-1,4-pentadien-3-one - VA veratryl alcohol     

Chromosomal localization of uroplakin genes of cattle and mice

The asymmetric unit membrane (AUM) of the apical surface of mammalian urinary bladder epithelium contains several major integral membrane proteins, including uroplakins IA and IB (both 27 kDa), II (15 kDa), and III (47 kDa). These proteins are synthesized only in terminally differentiated bladder epithelial cells. They are encoded by separate genes and, except for uroplakins IA and IB, appear to be unrelated in their amino acid sequences. The genes encoding these uroplakins were mapped to chromosomes of cattle through their segregation in a panel of bovine x rodent somatic cell hybrids. Genes for uroplakins IA, IB, and II were mapped to bovine (BTA) Chromosomes (Chrs) 18 (UPK1A), 1 (UPK1B), and 15 (UPK2), respectively. Two bovine genomic DNA sequences reactive with a uroplakin III cDNA probe were identified and mapped to BTA 6 (UPK3A) and 5 (UPK3B). We have also mapped genes for uroplakins 1A and II in mice, to the proximal regions of mouse Chr 7 (Upk1a) and 9 (Upk2), respectively, by analyzing the inheritance of restriction fragment length variants in recombinant inbred mouse strains. These assignments are consistent with linkage relationships known to be conserved between cattle and mice. The mouse genes for uroplakins IB and III were not mapped because the mouse genomic DNA fragments reactive with each probe were invariant among the inbred strains tested. Although the stoichiometry of AUM proteins is nearly constant, the fact that the uroplakin genes are unlinked indicates that their expression must be independently regulated. Our results also suggest likely positions for two human uroplakin genes and should facilitate further analysis of their possible involvement in disease.