Genetic transformation via particle bombardment of Catharanthus roseus plants through adventitious organogenesis of buds

In vitro propagation of Catharanthus roseus was achieved using nodal explants. Bud induction was best on medium containing 1.0 mg benzyl aminopurine l^–1. Hardening of rooted shoots to soil was very successful with 98% survival. Genetically transformed C. roseus plantlets were obtained after bombardment of nodal explants, which were then micropropagated, with DNA coated particles with green fluorescent protein (GFP) or -glucuronidase (GUS) reporter genes. Histological studies showed that the gene insertion method proved effective with many cells and different tissues displaying the reporter gene signals, showing that gene expressions were rather stable.     

Why do chlorosomal chlorophylls lack the C132 -methoxycarbonyl moiety? An in vitro model study

Effects of the C13²-methoxycarbonyl moiety on the self-assembly of chlorosomal chlorophylls (Chls) were studied. Model compounds, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-pheophorbides a and a (Zn-3¹-OH-Chls a/a, C13²-epimers) were synthesized from Chl a, and their aggregation behaviors were examined in Triton X-100 (TX-100) micellar suspensions and in 6%THF/water, in comparison with those of a pyrolized derivative, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-13²-demethoxycarbonyl-pheophorbide a (Zn-3¹-OH-pyroChl a). Zn-3¹-OH-Chl a formed self-aggregates in the TX-100 micellar suspension and gave a Q_y absorption peak at 703 nm, while Zn-3¹-OH-pyroChl a aggregates of a Q_y peak at 740 nm. In the Zn-3¹-OH-Chl a aggregate spectrum, the Q_y red-shift was smaller, the band shape was broader, and the contribution of the residual monomer was more intense than that in the Zn-3¹-OH-pyroChl a aggregate spectrum. The bulky C13²-moiety limits the ways of molecular association, and electronic interaction between the component molecules of the Zn-3¹-OH-Chl a aggregate is weakened. Stereoselective control of the aggregation of the C13²-epimer was also examined.     

Methane emissions from wet grasslands on peat soil in a nature preserve

The area of wet grasslands on peat soil in the Netherlands is slowly increasing at the expense of drained, agriculturally used grasslands. This study aimed (i) to assess the contribution of wet grasslands on peat soil to methane (CH₄) emissions, and (ii) to explain differences among sites and between years in order to improve our understanding of controlling factors. For these purposes, a field study was conducted in the period 1994–1996 in the nature preserve Nieuwkoopse Plassen, which is a former peat mining and agricultural area. Net CH₄ emissions were measured weekly to monthly with vented closed flux chambers at three representative sites, and at ditches near these sites. Three-years average of CH₄ emissions was 7.9 g CH₄ m^–2 yr^–1 for Drie Berken Zudde, 13.3 for Koole, and 20.4 for Brampjesgat. Ditches near the sites emitted 4.2–22.5 g CH₄ m^–2 yr^–1. The time-course of CH₄ emissions for all experimental sites and years was fit with a multiple linear regression model with ground water level and soil temperature as independent variables. Lowering or raising the ground water level by 5 cm could decrease or increase CH₄ emissions by 30–50%. Therefore, ground water level management of these grasslands should be done with care.     

Seasonal patterns of tissue water relations in three Mediterranean shrubs co‐occurring at a natural CO2 spring

Seasonal changes in tissue water relations of Erica arborea L., Myrtus communis L. and Juniperus communis L., grown in a Mediterranean environment, were analysed under field conditions over a 12 month period by comparing plants grown in the proximity of a natural CO₂ spring (about 700 μ mol mol ^{? 1} atmospheric CO₂ concentration, [CO₂]) with plants in ambient conditions. Tissue water relations varied in response to changes in water availability, but the seasonal course of tissue water relations parameters was also related to ontogeny. Tissue water relations of these co‐occurring shrubs were not alike. Osmotic potentials and saturated mass/dry mass ratio were lowest during peak drought stress periods. Diurnal changes in osmotic potential at the point of turgor loss were least early in the season, maximal in mid‐season, and decreased again in autumn. Turgor potentials decreased as drought progressed and were highest in late fall and mid‐winter. Symplastic water fraction was highest in mid‐spring for E. arborea and M. communis and decreased during the summer, while the opposite was observed for J. communis. Common to all species, under elevated [CO₂], was an increase of turgor pressure, particularly during the summer months. Other parameters showed species‐specific responses to long‐term elevated [CO₂]. In particular, exposure to elevated [CO₂] increased osmotic potentials in E. arborea under drought, while the opposite was the case for J. communis. Site differences in predawn to midday shifts were not strong in any of the species. Differences in tissue water relations suggest that the coexistence of these shrubs in the same environment with similar water availability are partially based on differential water relations strategies and water use patterns. Regardless of the mechanisms, growth of these shrubs in elevated [CO₂] may be either less, similarly or more affected by drought stress than plants in ambient [CO₂] depending on the species and season.     

Helicobacter pylori in Japanese river water and its prevalence in Japanese children

AIMS: The major transmission route of Helicobacter pylori remains unclear. In this study, we examined H. pylori in the environmental waters in Japan. METHODS AND RESULTS: A total of 24 water samples were collected from the upper, middle and downstream reaches of four Japanese rivers. Helicobacter pylori-specific DNA was examined using nested PCR. In addition, 224 children who lived near one river were studied by the stool antigen test for H. pylori prevalence. Helicobacter pylori DNA was detected in the water from the middle and downstream reaches of all four rivers, but not in the upper reaches. Helicobacter pylori was not found in cultured water samples with positive PCR results. Helicobacter pylori prevalence in the children examined was 9.8% for those living near the middle reaches and 23.8% nearby downstream, both of which were higher than the value in an area distant from the river (0%) (both, P < 0.01). CONCLUSIONS: Difference in H. pylori prevalence in the children may be related to the presence of H. pylori in the river. The results of this study showed that H. pylori DNA is frequently present in river water from the middle and downstream reaches in which the human biosphere is embedded. SIGNIFICANCE AND IMPACT OF THE STUDY: It is suggested that river water in the natural environment could be a risk factor for H. pylori transmission.     

Molecular confirmation of Enterococcus faecalis and E. faecium from clinical, faecal and environmental sources

AIMS: The genus Enterococcus includes opportunistic pathogens such as E. faecalis and E. faecium, and is also used to assess water quality. Speciation of enterococci in environmental studies can be particularly problematic, therefore protocols for unambiguous, DNA-based analysis could receive wide use in applications ranging from water quality monitoring to microbial source tracking. The goal of this work was to investigate the usefulness of PCR for speciation of putative, biochemically identified E. faecalis and E. faecium isolated from water, faeces and sewage. METHODS AND RESULTS: Putative enterococci (n = 139) were isolated on mEI agar from dog, human, gull and cow faeces, and from sewage, freshwaters and marine waters. A total of 128 isolates passed standard physiological tests for the genus, and were speciated by the API 20 Strep (APIStrep) biochemical test system. 42.2% were identified as E. faecalis, and all were confirmed by PCR. 19.5% were biochemically identified as E. faecium, but only seven were PCR-positive. CONCLUSIONS: The 16S rDNA of PCR-positive and PCR-negative E. faecium, including isolates that were inconclusively identified by APIStrep, was sequenced. All formed a monophyletic clade with E. faecium sequences in Genbank. SIGNIFICANCE AND IMPACT OF THE STUDY: Biochemical identification of E. faecalis agreed 100% with PCR assays, therefore a simple protocol of isolation on mEI followed by PCR should be useful for environmental studies. Discrepancies among biochemical identification, PCR confirmation and DNA sequencing were noted for E. faecium, indicating that routine isolation/identification of E. faecium from environmental samples is a much more difficult task.     

Exceptional Photosynthetic Performance of Capparis spinosa L. Under Adverse Conditions of Mediterranean summer

Diurnal and seasonal fluctuations in water potential (), stomatal conductance (g _s), transpiration rate (E), and net photosynthetic rate (P _N) were monitored in Capparis spinosa L., a Mediterranean plant growing during summer, i.e. at the period considered the most stressful for local plant life. In spite of the complete absence of rain, exhibited a modest drop at midday (–2.7 MPa), but was fully recovered overnight, indicating sufficient access to water sources. The stomata remained open throughout the day and season and the high E resulted in leaf temperatures up to 3.9 °C below air temperature. Additionally, P _N of the fully exposed leaves was higher than 25 mol m^–2 s^–1 for more than 10 h per day throughout the summer growth period. No symptoms of photooxidative stress were shown, as judged by maximum photosystem 2 photochemical efficiency (F_v/F_m) and the function of xanthophyll cycle. Indeed, diurnal inter-conversions of the xanthophyll cycle components were modest during the summer and a more intensive function of the cycle was only evident during leaf senescence in autumn. In comparison with a semi-deciduous and an evergreen sclerophyll co-existing in the same ecosystem, C. spinosa assimilated up to 3.4 times more CO₂ per m² during its growth period (May to October) and up to 1.8 times more on an annual basis.     

Birth and evolutionary history of a human minisatellite

One of the most exciting challenges in human biology is the understanding of how our genome was constructed during evolution. Here we explore the evolutionary history of the low polymorphic human minisatellite MsH42 and its flanking sequences. We show that the evolutionary birth of MsH42 took place within an intron, early in primate lineage evolution, more than 40 MYA. Then, single base-pair changes and duplications/deletions of repeat blocks by mispairing were probably the main forces governing the generation of this minisatellite and its polymorphism throughout primate evolution. Moreover, we detected several phylogenetic footprints at both sides of MsH42. We believe that our findings will contribute to the understanding of low-variability minisatellite evolution.