Catch-up growth in Japanese quail (Coturnix Japonica): relationships with food intake, metabolic rate and sex

The effects of early environmental conditions can profoundly affect individual development and adult phenotype. In birds, limiting resources can affect growth as nestlings, but also fitness and survival as adults. Following periods of food restriction, individuals may accelerate development, undergoing a period of rapid “catch-up” growth, in an attempt to reach the appropriate size at adulthood. Previous studies of altricial birds have shown that catch-up growth can have negative consequences in adulthood, although this has not been explored in species with different developmental strategies. Here, we investigated the effects of resource limitation and the subsequent period of catch-up growth, on the morphological and metabolic phenotype of adult Japanese quail (Coturnix japonica), a species with a precocial developmental strategy. Because males and females differ in adult body size, we also test whether food restriction had sex-specific effects. Birds that underwent food restriction early in development had muscles of similar size and functional maturity, but lower adult body mass than controls. There was no evidence of sex-specific sensitivity of food restriction on adult body mass; however, there was evidence for body size. Females fed ad lib were larger than males fed ad lib, while females subjected to food restriction were of similar size to males. Adults that had previously experienced food restriction did not have an elevated metabolic rate, suggesting that in contrast to altricial nestlings, there was no metabolic carry-over effect of catch-up growth into adulthood. While Japanese quail can undergo accelerated growth after re-feeding, timing of food restriction may be important to adult size, particularly in females. However, greater developmental flexibility compared to altricial birds may contribute to the lack of metabolic carryover effects at adulthood.     

Maize chromosomal knobs are located in gene-dense areas and suppress local recombination

Knobs are conspicuous heterochromatic regions found on the chromosomes of maize and its relatives. The number, locations, and sizes of knobs vary dramatically, with most lines containing between four and eight knobs in mid-arm positions. Prior data suggest that some knobs may reduce recombination. However, comprehensive tests have not been carried out, primarily because most knobs have not been placed on the genetic map. We used fluorescent in situ hybridization and two recombinant inbred populations to map seven knobs and to accurately place three knobs from the B73 inbred on the genomic sequence assembly. The data show that knobs lie in gene-dense regions of the maize genome. Comparisons to 23 other recombinant inbred populations segregating for knobs at the same sites confirm that large knobs can locally reduce crossing over by as much as twofold on a cM/Mb scale. These effects do not extend beyond regions ~10 cM to either side of knobs and do not appear to affect linkage disequilibrium among genes within and near knob repeat regions of the B73 RefGen_v2 assembly.     

RECONSTRUCTING THE COMPLEX EVOLUTIONARY ORIGIN OF WILD ALLOPOLYPLOID TOBACCOS (NICOTIANA SECTION SUAVEOLENTES)

Nicotiana (Solanaceae) provides an ideal system for understanding polyploidization, a pervasive and powerful evolutionary force in plants, as this genus contains several groups of allotetraploids that formed at different times from different diploid progenitors. However, the parental lineages of the largest group of allotetraploids, Nicotiana section Suaveolentes, have been problematic to identify. Using data from four regions of three low‐copy nuclear genes, nuclear ribosomal DNA, and regions of the plastid genome, we have reconstructed the evolutionary origin of sect. Suaveolentes and identified the most likely diploid progenitors by using a combination of gene trees and network approaches to uncover the most strongly supported evidence of species relationships. Our analyses best support a scenario where a member of the sect. Sylvestres lineage acted as the paternal progenitor and a member of either sect. Petunioides or sect. Noctiflorae that also contained introgressed DNA from the other, or a hypothetical hybrid species between these two sections, was the maternal progenitor. Nicotiana exemplifies many of the factors that can complicate the reconstruction of polyploid evolutionary history and highlights how reticulate evolution at the diploid level can add even greater complexity to allopolyploid genomes.     

Sensitivity to RNA interference-mediated gene silencing in intact and ligated larvae of the armyworm, Mythimna separata (Lepidoptera: Noctuidae)

RNA interference (RNAi) is a common tool for analysis of gene function in both model and non-model insects, but it is becoming evident that RNAi efficiency varies considerably from species to species. We examined RNAi efficiency in larvae of the armyworm Mythimna separata (Walker) using multiple genes and tissues. First, we showed that five different target genes exhibited distinct tissue distribution patterns by quantitative determination of mRNA in total hemocytes, foregut, midgut, hindgut, Malpighian tubules and fat body: neuroglian mRNA was most abundant in fat body; inhibitor of apoptosis proteins mRNA was found to be ubiquitous; aquaporin 4 mRNA was most enriched in hindgut; cueball and prophenoloxidase 2 were mainly expressed in hemocytes. Second, we assessed sensitivity to gene silencing by double-strand RNA injection of these five genes in the six different tissues. We found that these genes generally showed refractoriness to double-strand RNA-mediated gene knockdown irrespective of the tissue tested. Finally, we demonstrated that appreciable gene knockdown was achieved at least in the adhering hemocyte fraction when larval isolated abdomen was prepared by ligation and subjected to dsRNA injection. Our study thus added detailed information on the refractoriness of larval tissues of a lepidopteran insect to gene silencing through RNAi and provided a new potential approach to improve RNAi efficiency.     

Advanced glycation end products suppress osteoblastic differentiation of stromal cells by activating endoplasmic reticulum stress

Advanced glycation end products (AGEs) are involved in bone quality deterioration in diabetes mellitus. We previously showed that AGE2 or AGE3 inhibited osteoblastic differentiation and mineralization of mouse stromal ST2 cells, and also induced apoptosis and decreased cell growth. Although quality management for synthesized proteins in endoplasmic reticulum (ER) is crucial for the maturation of osteoblasts, the effects of AGEs on ER stress in osteoblast lineage are unknown. We thus examined roles of ER stress in AGE2- or AGE3-induced suppression of osteoblastogenesis of ST2 cells. An ER stress inducer, thapsigargin (TG), induced osteoblastic differentiation of ST2 cells by increasing the levels of Osterix, type 1 collagen (Col1), alkaline phosphatase (ALP) and osteocalcin (OCN) mRNA. AGE2 or AGE3 suppressed the levels of ER stress sensors such as IRE1α, ATF6 and OASIS, while they increased the levels of PERK and its downstream molecules, ATF4. A reduction in PERK level by siRNA did not affect the AGEs-induced suppression of the levels of Osterix, Col1 and OCN mRNA. In conclusion, AGEs inhibited the osteoblastic differentiation of stromal cells by suppressing ER stress sensors and accumulating abnormal proteins in the cells. This process might accelerate AGEs-induced suppression of bone formation found in diabetes mellitus.     

Breast cancer cell behaviors on staged tumorigenesis-mimicking matrices derived from tumor cells at various malignant stages

Extracellular matrix (ECM) has been focused to understand tumor progression in addition to the genetic mutation of cancer cells. Here, we prepared “staged tumorigenesis-mimicking matrices” which mimic in vivo ECM in tumor tissue at each malignant stage to understand the roles of ECM in tumor progression. Breast tumor cells, MDA-MB-231 (invasive), MCF-7 (non-invasive), and MCF-10A (benign) cells, were cultured to form their own ECM beneath the cells and formed ECM was prepared as staged tumorigenesis-mimicking matrices by decellularization treatment. Cells showed weak attachment on the matrices derived from MDA-MB-231 cancer cells. The proliferations of MDA-MB-231 and MCF-7 was promoted on the matrices derived from MDA-MB-231 cancer cells whereas MCF-10A cell proliferation was not promoted. MCF-10A cell proliferation was promoted on the matrices derived from MCF-10A cells. Chemoresistance of MDA-MB-231 cells against 5-fluorouracil increased on only matrices derived from MDA-MB-231 cells. Our results showed that the cells showed different behaviors on staged tumorigenesis-mimicking matrices according to the malignancy of cell sources for ECM preparation. Therefore, staged tumorigenesis-mimicking matrices might be a useful in vitro ECM models to investigate the roles of ECM in tumor progression.     

Dual role of p53 amyloid formation in cancer; loss of function and gain of toxicity

The tumor suppressor p53 plays an important role in genome integrity. It is frequently mutated in all types of human cancers, making p53 a key factor in cancer progression. Two phenotypic consequences of these alterations are dominant; a loss of function and a gain of function of p53, which, in several cases, accumulates in intracellular aggregates. Although the nature of such aggregates is still unclear, recent evidence indicates that p53 can undergo conformational transitions leading to amyloid formation. Amyloid diseases, such as, Alzheimer’s disease, are characterized by the accumulation of insoluble aggregates displaying the fibrillar conformation. We decided to investigate the propensity of wild type p53 to aggregate and its consequent assembly into different amyloid species, such as oligomers and fibrils; and to determine if these changes in conformation lead to a loss of function of p53. Furthermore, we analyzed cases of Basal Cell Carcinoma (BCC), for the presence of p53 amyloids. Here, we show that p53 forms amyloid oligomers and fibrils, which coincide with p53 inability of binding to DNA consensus sequences. Both p53 amyloid oligomers and fibrils were detected in BCC cancer samples. Additionally, we demonstrate that p53 oligomers are the most cytotoxic to human cell cultures.Our study reveals p53 amyloid formation and demonstrates its dual role in the pathogenesis of cancer by producing a loss of protein function and a gain of toxic function, extensively described in several amyloidogenic diseases. Our results suggest that under certain circumstances, cancer could be considered a protein-conformation disease.     

Nuclear-encoded chloroplast RNA polymerase sigma factor SIG2 activates chloroplast-encoded phycobilisome genes in a red alga, Cyanidioschyzon merolae

The phycobilisome (PBS) is a photosynthetic light-harvesting complex in red algae, whose structural genes are separately encoded by both the nuclear and chloroplast genomes. While the expression of PBS genes in both genomes is responsive to environmental changes to modulate light-harvesting efficiency, little is known about how gene expression of the two genomes is coordinated. In this study, we focused on the four nuclear-encoded chloroplast sigma factors to understand aspects of this coordination, and found that SIG2 directs the expression of chloroplast PBS genes in the red alga Cyanidioschyzon merolae.