Autoregulation of Nisin Biosynthesis in Lactococcus lactis by Signal Transduction

The post-translationally modified, antimicrobial peptide nisin is secreted by strains of Lactococcus lactis that contain the chromosomally located nisin biosynthetic gene cluster nisABTCIPRKFEG. When a 4-base pair deletion is introduced into the structural nisA gene (ΔnisA), transcription of ΔnisA is abolished. Transcription of the ΔnisA gene is restored by adding subinhibitory amounts of nisin, nisin mutants, or nisin analogs to the culture medium, but not by the unmodified precursor peptide or by several other antimicrobial peptides. Upon disruption of the nisK gene, which encodes a putative sensor protein that belongs to the class of two-component regulators, transcription of ΔnisA was no longer inducible by nisin. Fusion of a nisA promoter fragment to the promoterless reporter gene gusA resulted in expression of gusA in L. lactis NZ9800 (ΔnisA) only upon induction with nisin species. The expression level of gusA was directly related to the amount of inducer that was added extracellularly. These results provide insight into a new mechanism of autoregulation through signal transduction in prokaryotes and demonstrate that antimicrobial peptides can exert a second function as signaling molecules.

Photophysics of lead-free tin halide perovskite films and solar cells

The last five years have seen very active research in the field of environmentally friendly lead-free perovskite solar cells. Tin halide perovskites are certainly one of the most promising alternatives to lead-based perovskites, while the performance of present tin-based perovskite solar cells is still relatively low. Nevertheless, recent experiments on thin films with improved quality have indicated that tin halide perovskites can, in principle, provide a high device performance. In this Perspective, we summarize recent progress in the understanding of the fundamental photophysics of tin halide perovskite thin films. To identify the reason for the low performance of present devices, we discuss the energy loss mechanisms in solar cell structures from the viewpoint of photocarrier dynamics

Biological Functions of the Novel Collectins CL-L1, CL-K1, and CL-P1

Collectins are characterized by a collagen-like sequence and a carbohydrate recognition domain and are members of the vertebrate C-type lectin superfamily. Recently, “novel collectins”, different from “classical collectins” consisting of mannan-binding lectin (MBL) and surfactant proteins A and D (SP-A and SP-D), have been found by reverse genetics. These “novel collectins” consist of collectin liver 1 (CL-L1), collectin kidney 1 (CL-K1), and collectin placenta 1 (CL-P1) and are encoded by three separate genes. Experimental findings on human and animal collectins have shown that both novel collectins and classical collectins play an important role in innate immunity. Based on our recent results and those of others, in this paper, we summarize the new biological functions of these novel collectins in embryonic morphogenesis and development

Shepherding Heterogeneous Flocks: Overview and Prospect

The problem of guiding a flock of several autonomous agents using repulsion force exerted by a smaller number of agents is called the shepherding problem and has been attracting attention due to its potential engineering applications. Although several works propose methodologies for achieving the shepherding task in this context, most assume that sheep agents have the same dynamics, which only sometimes holds in reality. The objective of this discussion paper is to overview a recent research trend addressing the gap mentioned above between the commonly placed uniformity assumption and the reality. Specifically, we first introduce recent guidance methods for heterogeneous flocks and then describe the prospects of the shepherding problem for heterogeneous flocks

ICR News 2022

This Annual Report covers from 1 January to 31 December 202