Environment-conditioned male fertility of HD-ZIP IV transcription factor mutant ocl4: impact on 21-nt phasiRNA accumulation in pre-meiotic maize anthers

Environment-conditioned genic male sterility is a key strategy used to produce hybrid seeds efficiently in many crops, with the exception of maize. The underlying molecular mechanisms of environment-conditioned sterility are poorly understood. Here, we report a derivative line of the male sterile outer cell layer 4 (ocl4) mutant of maize, in which fertility was restored and perpetuated over several generations, under warm growing conditions. Conditionally fertile ocl4 anthers exhibit the anatomical abnormality of a partially duplicated endothecial layer, just like their sterile counterparts. We profiled the dynamics of phased, small interfering RNAs (phasiRNAs) during pre-meiotic development in fully sterile and various grades of semi-fertile ocl4 anthers. We found that the biogenesis of 21-nt phasiRNAs is largely dependent on Ocl4 at three key steps: (1) production of PHAS precursor transcripts, (2) expression of miR2118 that modulates precursor processing, and (3) accumulation of 21-nt phasiRNAs. We propose that 21-nt reproductive phasiRNAs buffer development under unfavorable environmental conditions and are dispensable under favorable conditions.

Induced aneuploidy disrupts MCF10A acini formation and CCND1 expression

ABSTRACTAbnormal karyotypes, namely aneuploidy, can be detected in nearly all cancer entities at different grades. The impact of these altering mutations on epigenetic regulation, especially on promoter-enhancer interactions are not well understood. Here, we applied a 3D model of MCF10A cells in a high-content screen to measure induced aneuploidy by RNA interference of 82 mitotic genes associated with aneuploidy and breast cancer. Perturbation of ESPL1 and TOP2A expression led to increased mitotic instability and subsequent aneuploidy and polylobed nuclei. During acinus formation these polylobed cells disrupted proper acinus rotation inhibiting the development of a hollow lumen and a polarized outer cell layer. Further, gene expression profiling identified upregulated CCND1 among other breast cancer related genes. We show that acquisition of aneuploidy affects the morphogenesis of MCF10A acini and expression of cancer relevant genes. By conducting 4C chromosome capturing experiments we linked the alteration of interactions of the promoter region to CCND1 upregulation.

The multiple functions of the proepicardial/epicardial cell lineage in heart development

The epicardium is the outer cell layer of the vertebrate heart. In recent years, both the embryonic and adult epicardium have revealed unsuspected peculiarities and functions, which are essential for cardiac development. In this chapter we review the current literature on the epicardium, and describe its evolutionary origin, the mechanisms leading to the induction of its extracardiac progenitor tissue, the proepicardium, and the way in which the proepicardium is transferred to the heart to form the epicardium. We also describe the epicardial epithelial–mesenchymal transition from which mesenchymal cells originate, and the developmental fate of these cells, which contribute to the vascular, interstitial, valvular, and adipose tissue. Finally, we review the molecular interactions established between the epicardium and the myocardium, which are key for myocardial development and can also play a role in cardiac homeostasis. This chapter highlights how the epicardium has become a major protagonist in cardiac biology.

The nervous system of the neotropical millipede Gymnostreptus olivaceus Schubart, 1944 (Spirostreptida, Spirostreptidae) shows an additional cell layer

This study presents a morphological description of the central nervous system of the neotropical millipede Gymnostreptus olivaceus and the first report of an outer cell layer surrounding the nervous system in Diplopoda. The nervous system of this species consists of a brain formed by the fusion of proto-, deuto- and tritocerebrum, as well as a ventral nerve cord with metamerically arranged ganglia that extends through the entire length of the animal’s body. The optic lobes, mushroom bodies and olfactory glomeruli of this species were located and described. As has been reported for other millipedes, the nervous system of G. olivaceus comprises a cortical layer in which three types of neurons could be identified and an inner region of neuropil, both of which are wrapped and protected by a perineurium and a neural lamella. However, more externally to the neural lamella, there is a discontinuous and irregular outer cell sheath layer containing distinctive cells whose function appears to be linked to the nutrition and protection of neurons.

Lack of response of INT-407 cells to the presence of non-culturableCampylobacter jejuni

SUMMARYMany contradictory articles on the infectivity of non-culturableCampylobacter jejunican be found. We studied the effect of non-culturableC. jejuniin anin vitroassay. To prevent the potential effect of a few culturable bacteria in the non-culturable suspension, INT-407 cells, which mimic the outer cell layer in the small intestines, were exposed to culturableC. jejunisuspensions with or without non-culturableC. jejuni. The number of bacteria adhering to and/or invading INT-407 cells and the IL-8 secretion were measured. No differences were found between bacterial suspensions with or without non-culturableC. jejuniadded. These findings show that non-culturableC. jejunido not adhere to or invade INT-407 cells and do not induce an immune response. As previous studies showed a correlation between the usedin vitroassays and the effectin vivo, our study strongly suggests that culturability is a good indicator of the risk forC. jejuniinfection.

Inactivation of swmA Results in the Loss of an Outer Cell Layer in a Swimming Synechococcus Strain

ABSTRACT The mechanism of nonflagellar swimming of marine unicellular cyanobacteria remains poorly understood. SwmA is an abundant cell surface-associated 130-kDa glycoprotein that is required for the generation of thrust in Synechococcus sp. strain WH8102. Ultrastructural comparisons of wild-type cells to a mutant strain in which the gene encoding SwmA has been insertionally inactivated reveal that the mutant lacks a layer external to the outer membrane. Cryofixation and freeze-substitution are required for the preservation of this external layer. Freeze fracturing and etching reveal that this additional layer is an S-layer. How the S-layer might function in motility remains elusive; however, this work describes an ultrastructural component required for this unique type of swimming. In addition, the work presented here describes the envelope structure of a model swimming cyanobacterium.

Na+/H+ exchangers in the human eccrine sweat duct

Using an anti-NHE1 antibody, we demonstrate the presence of a Na+/H+ exchanger of isoform 1 (NHE1) in the human eccrine sweat duct. A strong staining was observed at the basolateral membrane of the outer cell layer (NHE1basal), at the junction between inner and outer cells layers (NHE1inter), and along the lateral membranes (NHE1later) of all cells of the duct. At the luminal membrane, no staining was demonstrated either for NHE1 or NHE3. To investigate Na+/H+ mediated proton transport, straight sweat duct portions were isolated and perfused in vitro under HCO3--free conditions. In the presence of basolateral 5-ethyl- N-isopropyl amiloride (EIPA), an acidification of 0.29 ± 0.03 pH units was observed, whereas no effect was observed with luminal EIPA. Bath sodium removal generated a stronger acidification (0.41 ± 0.09 pH units). Removal of luminal sodium (in the absence or presence of basolateral EIPA), or low luminal chloride, led to an alkalinization, presumably due to a decrease in intracellular sodium, strongly suggesting functional activity of NHE1inter. We therefore conclude that in the sweat duct, NHE1 plays a major role in intracellular pH regulation.