Effect of Lincocin Treatment on the Greening Process in Bean (Phaseolus vulgaris) Leaves

The effect of lincocin (a plastid protein synthesis inhibitor) treatment on the greening process of bean (Phaseolus vulgaris L.) leaves have been studied. In comparison with control leaves treated ones had a decreased rate of chloroplast development. They had a marked chlorophyll deficiency and a decreased chlorophyll a/b ratio. Some long and short wavelength forms of chlorophyll a were lacking as evidenced from the absorption spectra at 25°C and the fluorescence spectra at 77°K. The –¹⁴CO₂ fixation was inhibited by 80–90% in treated leaves. The fluorescence induced by the measuring light was greater in the treated leaves than in the control ones, and the kinetics of the decline of the relative fluorescence intensity were also different. Electron microscopic studies showed macrogranum-like structures and incomplete membrane vesicles in the treated plastids. After longer treatment a destruction of membranes was observed. The results indicate some structural and functional membrane deficiencies and instability of the membranes.     

Polymorphisms in Genes of Relevance for Oestrogen and Oxytocin Pathways and Risk of Barrett’s Oesophagus and Oesophageal Adenocarcinoma: A Pooled Analysis from the BEACON Consortium

Background

The strong male predominance in oesophageal adenocarcinoma (OAC) and Barrett’s oesophagus (BO) continues to puzzle. Hormonal influence, e.g. oestrogen or oxytocin, might contribute.

Methods

This genetic-epidemiological study pooled 14 studies from three continents, Australia, Europe, and North America. Polymorphisms in 3 key genes coding for the oestrogen pathway (receptor alpha (ESR1), receptor beta (ESR2), and aromatase (CYP19A1)), and 3 key genes of the oxytocin pathway (the oxytocin receptor (OXTR), oxytocin protein (OXT), and cyclic ADP ribose hydrolase glycoprotein (CD38)), were analysed using a gene-based approach, versatile gene-based test association study (VEGAS).

Results

Among 1508 OAC patients, 2383 BO patients, and 2170 controls, genetic variants within ESR1 were associated with BO in males (p = 0.0058) and an increased risk of OAC and BO combined in males (p = 0.0023). Genetic variants within OXTR were associated with an increased risk of BO in both sexes combined (p = 0.0035) and in males (p = 0.0012). We followed up these suggestive findings in a further smaller data set, but found no replication. There were no significant associations between the other 4 genes studied and risk of OAC, BO, separately on in combination, in males and females combined or in males only.

Conclusion

Genetic variants in the oestrogen receptor alpha and the oxytocin receptor may be associated with an increased risk of BO or OAC, but replication in other large samples are needed.     

Land plants acquired active stomatal control early in their evolutionary history

Stomata are pores that regulate plant gas exchange [1]. They evolved more than 400 million years ago [2, 3], but the origin of their active physiological responses to endogenous and environmental cues is unclear [2-6]. Recent research suggests that the stomata of lycophytes and ferns lack pore closure responses to abscisic acid (ABA) and CO(2). This evidence led to the hypothesis that a fundamental transition from passive to active control of plant water balance occurred after the divergence of ferns 360 million years ago [7, 8]. Here we show that stomatal responses of the lycophyte Selaginella [9] to ABA and CO(2) are directly comparable to those of the flowering plant Arabidopsis [10]. Furthermore, we show that the underlying intracellular signaling pathways responsible for stomatal aperture control are similar in both basal and modern vascular plant lineages. Our evidence challenges the hypothesis that acquisition of active stomatal control of plant carbon and water balance represents a critical turning point in land plant evolution [7, 8]. Instead, we suggest that the critical evolutionary development is represented by the innovation of stomata themselves and that physiologically active stomatal control originated at least as far back as the emergence of the lycophytes (circa 420 million years ago) [11].