Evolution of low-light adapted peripheral light-harvesting complexes in strains of Rhodopseudomonas palustris

Purple bacteria have peripheral light-harvesting (PLH) complexes adapted to high-light (LH2) and low-light (LH3, LH4) growth conditions. The latter two have only been fully characterised in Rhodopseudomonas acidophila 7050 and Rhodopseudomonas palustris CGA009, respectively. It is known that LH4 complexes are expressed under the control of two light sensing bacteriophytochromes (BphPs). Recent genomic sequencing of a number of Rps. palustris strains has provided extensive information on PLH genes. We show that both LH3 and LH4 complexes are present in Rps. palustris and have evolved in the same operon controlled by the two adjacent BphPs. Two rare marker genes indicate that a gene cluster CL2, containing LH2 genes and the BphP RpBphP4, was internally transferred within the genome to form a new operon CL1. In CL1, RpBphP4 underwent gene duplication to RpBphP2 and RpBphP3, which evolved to sense light intensity rather than spectral red/far-red intensity ratio. We show that a second LH2 complex was acquired in CL1 belonging to a different PLH clade and these two PLH complexes co-evolved together into LH3 or LH4 complexes. The near-infrared spectra provide additional support for our conclusions on the evolution of PLH complexes based on genomic data.     

In vitro and in vivo evaluation of insulin-producing beta TC6-F7 cells in microcapsules

In the present study, the insulin secretory capacity ofTC6-F7 cells in microcapsules was evaluated. The cell mass within capsules was found to expand in a three-dimensional fashion, in contrast to cells seeded on plates that grew as a monolayer. In invitro studies, both free and encapsulated cells were found to secreteinsulin in the absence of glucose, at 13.6 ± 1.1 and 14.5 ± 0.9 ng · 10⁶cells¹ · 60 min¹, respectively, withthe response rising to a maximum of 26.0 ± 0.8 and 31 ± 2.3 ng · 10⁶cells¹ · 60 min¹ in the presence of16.8 mM glucose. Encapsulated cells were able to produceCa²⁺ responses in the presence ofKCl (50 mM) and BAY K 8644 (100 µM). In in vivo studies,intraperitoneal transplantation of 3.0 ×10⁶ microencapsulated cellsinto mice (n = 5) withstreptozotocin-induced diabetes resulted in the restoration ofnormoglycemia up to 57 days. Insulin concentrations rose from 0.4 ± 0.1 ng/ml before the graft administration to 2.2 ± 0.8 ng/ml afterthe transplantation in the normoglycemic recipients. An oral glucosechallenge in transplant recipients demonstrated a flat glucoseresponse, suggesting extremely high glucose clearance rates. These datademonstrate the potential use of the immunoisolated -cell lines forthe treatment of diabetes.

     

Correlation between the number of adult male Pectinophora gossypiella (Saund.) (Lep., Gelechidae) catches on pheromone traps and the rate of infestation in fruiting bodies of cotton plants by young larvae in three regions of central Greece

In order to evaluate the influence of the number of catches in pheromone-baited traps on the percentage of larval infestation, six delta traps equipped with sex attractant were placed in each of three regions in Central Greece (Farkadona, Farsala, Almyros) in cotton fields from 20 June until 30 September 1995. The collection of fruiting bodies took place weekly and the counting of adults in the traps was carried out each day. The population fluctuation in all three regions was similar with their peak during the first weeks of August. In Farkadona the infestation level was low (1% at the first sampling of August) with a maximum of 9% in the last sampling of September. In Farsala and Almyros, the infestation level was already high (10% and above) in early August. There was a significant positive linear correlation between the number of moth catches and the infestation percentage from first- and second-stage larvae on the first (R = 0694) and second (R = 0.7399) boll-feeding generations.     

Paranoia,self-deception and overconfidence

Self-deception, paranoia, and overconfidence involve misbeliefs about the self, others, and world. They are often considered mistaken. Here we explore whether they might be adaptive, and further, whether they might be explicable in Bayesian terms. We administered a difficult perceptual judgment task with and without social influence (suggestions from a cooperating or competing partner). Crucially, the social influence was uninformative. We found that participants heeded the suggestions most under the most uncertain conditions and that they did so with high confidence, particularly if they were more paranoid. Model fitting to participant behavior revealed that their prior beliefs changed depending on whether the partner was a collaborator or competitor, however, those beliefs did not differ as a function of paranoia. Instead, paranoia, self-deception, and overconfidence were associated with participants’ perceived instability of their own performance. These data are consistent with the idea that self-deception, paranoia, and overconfidence flourish under uncertainty, and have their roots in low self-esteem, rather than excessive social concern. The model suggests that spurious beliefs can have value–self-deception is irrational yet can facilitate optimal behavior. This occurs even at the expense of monetary rewards, perhaps explaining why self-deception and paranoia contribute to costly decisions which can spark financial crashes and devastating wars.