Enhanced thermal stability and mismatch discrimination of mutation-carrying DNA duplexes and their kinetic and thermodynamic properties in microchannel laminar flow

This article reports the enhancement of thermal stability involving normal duplex and mutation-carrying DNA duplexes in microchannel laminar flow. The application of an in-house temperature-controllable microchannel-type flow cell is demonstrated for improved discrimination of mismatch base pairs such as A-G and T-G that are difficult to distinguish due to the rather small thermal destabilizations. Enhancement in thermal stability is reflected by an increased thermal melting temperature achieved in microchannel laminar flow as compared with batch reactions. To examine the kinetics and thermodynamics of duplex-coil equilibrium of DNA oligomers, denaturation-renaturation hysteresis curves were measured. The influence of microchannel laminar flow on DNA base mismatch analysis was described from the kinetic and thermodynamic perspectives. An increasing trend was observed for association rate constant as flow rate increased. In contrast, an apparent decrease in dissociation rate constant was observed with increasing flow rate. The magnitudes of the activation energies of dissociation were nearly constant for both the batch and microchannel laminar flow systems at all flow rates. In contrast, the magnitudes of activation energies of association decreased as flow rate increased. These results clearly show how microchannel laminar flow induces change in reaction rate by effecting change in activation energy. We anticipate, therefore, that this approach based on microchannel laminar flow system holds great promise for improved mismatch discrimination in DNA analyses, particularly on single-base-pair mismatch, by pronouncedly enhancing thermal stability.     

Monograph of Carex section Schiedeanae (Cyperaceae): Unexpected taxonomic and ecological diversity in a Mexican sedge clade

Carex section Schiedeanae (subg. Euthyceras) has long been thought to comprise at most five species of Mexican sedges. Our morphological studies in the field and herbarium, however, supported by more recent DNA sequencing work, demonstrate that the section is, in fact, three times as species-rich, making it one of the largest sections in Mexico. Its 15 species range from Chihuahua to Tamaulipas south to Veracruz and Oaxaca; a single species, Carex muriculata, extends into the United States. The section has unusual inflorescences with simple (except in Carex complexa), uniformly androgynous, sessile spikes, utriculiform cladoprophylls, and perigynia with a unique combination of pubescence types composed of papillae; unicellular, simple hairs; and (in many species) multicellular tubercles. We recognize five previously described species (C. muriculata,Carex perstricta,Carex schiedeana, Carex stellata, and Carex vizarronensis) and describe 10 additional species (Carex angustilepis, Carex cabralii, Carex complexa, Carex dentata, Carex gypsophila, Carex mesophila, Carex paneroi, Carex planilamina, Carex revoluta, and Carex tehuacana). We have expanded the morphological features used in the section to include particularly anther, staminate scale, and style features, and more detailed micromorphology of the perigynia, especially indumentum. In total, 13 of the 15 species recognized herein, with a total of 32 individuals, were examined for ETS and ITS for phylogenetic reconstruction. Phylogenetically, the xeric species (plus C. paneroi) form a grade leading to a clade of the more mesophytic species adapted to forest understories, plus the unique cliff dwelling C. complexa.     

Hepatoprotective and antineoplastic properties of Protaetia brevitarsis larvae

Protaetia brevitarsis larvae have been used as a traditional medicine to treat various liver diseases. Freeze‐dried powder and solvent partitioned fractions of Protaetia brevitarsis larvae, in this study, were examined for hepatoprotective and antitumor activities in vivo and in vitro. Oral administration of the powder reduced signs of acute and chronic liver injuries in diethylnitrosamine‐induced hepatotoxic mouse model. Various cancer cell types, but not normal primary hepatocytes, were killed by the hexane, ethyl acetate and butanol fractions, which were partitioned from larval extracts. Apoptosis and autophagy were primarily induced in cancer cells by hexane and ethyl acetate fractions, respectively, and can be the cytotoxic mechanisms of the fractions. Further analyses of the insect fractions could lead to identification of novel bioactive substances that can be exploited as therapeutics for various human liver diseases.     

Haem iron intake in 12-36 month old children depleted in iron: case-control study.

OBJECTIVE: To compare the intakes of haem and non-haem iron in iron depleted and iron replete children. DESIGN: Case-control study. SETTING: Early Childhood Centres and a long day care centre in Sydney, Australia. SUBJECTS: Children aged 12-36 months depleted in iron and controls matched for age and sex. MEAN OUTCOME MEASURES: Iron status by using plasma ferritin concentration. A three day weighed dietary intake record completed by the parents. Risk factors for iron deficiency assessed by questionnaire. RESULTS: Fifty six iron depleted and 68 iron replete children participated. The average daily intake of haem iron was significantly lower in the iron depleted group (t = 2.392, P = 0.018); there was a tendency towards a lower average daily intake of non-haem iron (t = 1.724, P = 0.086) and vitamin C (t = 1.921, P = 0.057) for iron depleted children. Low intake of haem iron (< 0.71 mg/day) was significantly associated with iron depletion with an odds ratio fo 3.0 (P = 0.005). The proportion of iron depleted children who were given whole cows'' milk before 12 months of age was almost double that of iron replete children; multivariate analysis showed that both haem iron intake and age of introduction of cows'' milk were independently associated with iron depletion. CONCLUSIONS: The results of this study show that, in young children in developed countries, a lower haem iron intake is a major risk factor for iron depletion; the introduction of whole cows'' milk before 12 months is further confirmed as a risk factor. Parental education on nutrition should now focus on these two aspects of nutrition for infants and young children.