Physiological changes in cultured sorghum cells in response to induced water stress : I. Free proline

Ten varieties of Sorghum bicolor (L.) Moench were grown as callus cultures under conditions of water stress, which was induced by addition of polyethylene glycol (molecular weight 8000) in the medium. Growth and free proline were estimated in the control and water-stressed cultures. In all varieties, proline levels were low in the absence of water stress and the levels increased in response to water stress. However, the magnitude of these increases were not correlated with stress tolerance of the individual varieties in culture. Thus increase in proline seems to be an incidental consequence of stress in vitro and not an adaptive response to combat water stress in sorghum.     

Screening for drought tolerance in Sorghum using cell culture

Summary Callus growth from 10 cultivars ofSorghum bicolor (L.) Moench was measured with increasing levels of polyethylene glycol (PEG) as an osmoticum in the medium to determine whether differences among these cultivars at the cellular level in response to osmotic stress existed. These cellular ratings were compared to field ratings from the 10 tolerant-to-susceptible cultivars when grown under drought conditions to determine whether cellular ratings corresponded to differences in drought tolerance at the plant level. Callus cultures were grown on Murashige and Skoog inorganic salt formulation plus vitamins, 2,4-dichlorophenoxyacetic acid (2,4-D), kinetin and sucrose, supplemented with 0 to 25% (wt/vol) PEG corresponding to −0.2 to −1.62 MPa osmotic potential. Results suggest that PEG-induced osmotic stress on callus cultures can be used to screen sorghum cultivars for potential early field (preflowering) drought tolerance. This implies that at least a component of the early field drought tolerance in sorghum may have a cellular basis. This study was supported by U.S. Agency for International Development Grant AID/DSAN/XII/G-0149, and USDA Competitive Grants Program.     

Th17 Inflammation Model of Oropharyngeal Candidiasis in Immunodeficient Mice

Oropharyngeal Candidiasis (OPC) disease is caused not only due to the lack of host immune resistance, but also the absence of appropriate regulation of infection-induced immunopathology. Although Th17 cells are implicated in antifungal defense, their role in immunopathology is unclear. This study presents a method for establishing oral Th17 immunopathology associated with oral candidal infection in immunodeficient mice. The method is based on reconstituting lymphopenic mice with in vitro cultured Th17 cells, followed by oral infection with Candida albicans (C. albicans). Results show that unrestrained Th17 cells result in inflammation and pathology, and is associated with several measurable read-outs including weight loss, pro-inflammatory cytokine production, tongue histopathology and mortality, showing that this model may be valuable in studying OPC immunopathology. Adoptive transfer of regulatory cells (T_regs) controls and reduces the inflammatory response, showing that this model can be used to test new strategies to counteract oral inflammation. This model may also be applicable in studying oral Th17 immunopathology in general in the context of other oral diseases.     

Effects of Vocal Fold Nodules on Glottal Cycle Measurements Derived from High-Speed Videoendoscopy in Children

The goal of this study is to quantify the effects of vocal fold nodules on vibratory motion in children using high-speed videoendoscopy. Differences in vibratory motion were evaluated in 20 children with vocal fold nodules (5–11 years) and 20 age and gender matched typically developing children (5–11 years) during sustained phonation at typical pitch and loudness. Normalized kinematic features of vocal fold displacements from the mid-membranous vocal fold point were extracted from the steady-state high-speed video. A total of 12 kinematic features representing spatial and temporal characteristics of vibratory motion were calculated. Average values and standard deviations (cycle-to-cycle variability) of the following kinematic features were computed: normalized peak displacement, normalized average opening velocity, normalized average closing velocity, normalized peak closing velocity, speed quotient, and open quotient. Group differences between children with and without vocal fold nodules were statistically investigated. While a moderate effect size was observed for the spatial feature of speed quotient, and the temporal feature of normalized average closing velocity in children with nodules compared to vocally normal children, none of the features were statistically significant between the groups after Bonferroni correction. The kinematic analysis of the mid-membranous vocal fold displacement revealed that children with nodules primarily differ from typically developing children in closing phase kinematics of the glottal cycle, whereas the opening phase kinematics are similar. Higher speed quotients and similar opening phase velocities suggest greater relative forces are acting on vocal fold in the closing phase. These findings suggest that future large-scale studies should focus on spatial and temporal features related to the closing phase of the glottal cycle for differentiating the kinematics of children with and without vocal fold nodules.     

Anthessius spp. (Anthessiidae) associated with Tridacnidae (Mollusca: Bivalvia) removed to a new genus Tridachnophilus

Genus Anthessius includes 36 species. Previous attempts to clarify the interspecific affinities reached no definite conclusions. Humes and Ho (1965) found that, based on the armature of the third exopod segment of the fourth leg, the known species could be arranged into two groups, but that this difference did not correspond with host preferences. The present study of A. alatus Humes and Stock shows that species of Anthessius associated with Tridacnidae differ from the rest (except A. fitchi Illg) in the marked indentation of the cephalosome and in the presence of well developed cephalosomal and metasomal epimeral lobes producing a very characteristic shape. They are here removed to a new genus, Tridachnophilus.     

Breaking Caenorhabditis elegans the easy way using the Balch homogenizer: an old tool for a new application

The biochemical quantification of sterols in insects has been difficult because only small amounts of tissues can be obtained from insect bodies and because sterol metabolites are structurally related. We have developed a highly specific and sensitive quantitative method for determining of the concentrations of seven sterols—7-dehydrocholesterol, desmosterol, cholesterol, ergosterol, campesterol, stigmasterol, and β-sitosterol—using a high performance liquid chromatography–atmospheric pressure chemical ionization–tandem mass spectrometry (HPLC/APCI-MS/MS). The sterols were extracted from silkworm larval tissues using the Bligh and Dyer method and were analyzed using HPLC/APCI-MS/MS with selected reaction monitoring, using cholesterol-3,4-¹³C₂ as an internal standard. The detection limits of the method were between 12.1 and 259 fmol. The major sterol in most silkworm larval tissues was cholesterol, whereas only small quantities of the dietary sterols were detected. Thus, a simple, sensitive, and specific method was successfully developed for the quantification of the sterol concentrations in each tissue of an individual silkworm larva. This method will be a useful tool for investigating to molecular basis of sterol physiology in insects, facilitating the quantification of femtomole quantities of sterols in biological samples.     

Co-expression of Pennisetum glaucum vacuolar Na⁺/H⁺ antiporter and Arabidopsis H⁺-pyrophosphatase enhances salt tolerance in transgenic tomato

Salinity is one of the major abiotic stresses affecting plant productivity. Tomato (Solanum lycopersicum L.), an important and widespread crop in the world, is sensitive to moderate levels of salt in the soil. To generate tomato plants that can adapt to saline soil, AVP1, a vacuolar H(+)-pyrophosphatase gene from Arabidopsis thaliana, and PgNHX1, a vacuolar Na(+)/H(+) antiporter gene from Pennisetum glaucum, were co-expressed by Agrobacterium tumefaciens-mediated transformation. A sample of transformants was self-pollinated, and progeny were evaluated for salt tolerance in vitro and in vivo. It is reported here that co-expression of AVP1 and PgNHX1 confers enhanced salt tolerance to the transformed tomato compared with the AVP1 and PgNHX1 single gene transgenic plants and the wild-type. These transgenic plants grew well in the presence of 200 mM NaCl while wild-type plants exhibited chlorosis and died within 3 weeks. The transgenic line co-expressing AVP1 and PgNHX1 retained more chlorophyll and accumulated 1.4 times more proline as a response to stress than single gene transformants. Moreover, these transgenic plants accumulated a 1.5 times higher Na(+) content in their leaf tissue than the single gene transformants. The toxic effect of Na(+) accumulation in the cytosol is reduced by its sequestration into the vacuole. The physiological analysis of the transgenic lines clearly demonstrates that co-expression of AVP1 and PgNHX1 improved the osmoregulatory capacity of double transgenic lines by enhanced sequestration of ions into the vacuole by increasing the availability of protons and thus alleviating the toxic effect of Na(+).