Developmental Processes In Organisms Research Articles

Two Isoforms of serpent Containing Either One or Two GATA Zinc Fingers Provide Functional Diversity During Drosophila Development.

GATA transcription factors play crucial roles in various developmental processes in organisms ranging from flies to humans. In mammals, GATA factors are characterized by the presence of two highly conserved domains, the N-terminal (N-ZnF) and the C-terminal (C-ZnF) zinc fingers. The Drosophila GATA factor Serpent (Srp) is produced in different isoforms that contains either both N-ZnF and C-ZnF (SrpNC) or only the C-ZnF (SrpC). Here, we investigated the functional roles ensured by each of these isoforms during Drosophila development. Using the CRISPR/Cas9 technique, we generated new mutant fly lines deleted for one (ΔsrpNC) or the other (ΔsrpC) encoded isoform, and a third one with a single point mutation in the N-ZnF that alters its interaction with its cofactor, the Drosophila FOG homolog U-shaped (Ush). Analysis of these mutants revealed that the Srp zinc fingers are differentially required for Srp to fulfill its functions. While SrpC is essential for embryo to adult viability, SrpNC, which is the closest conserved isoform to that of vertebrates, is not. However, to ensure its specific functions in larval hematopoiesis and fertility, Srp requires the presence of both N- and C-ZnF (SrpNC) and interaction with its cofactor Ush. Our results also reveal that in vivo the presence of N-ZnF restricts rather than extends the ability of GATA factors to regulate the repertoire of C-ZnF bound target genes.

Curvature-driven spatial patterns in growing 3D domains: A mechanochemical model for phyllotaxis.

Here we discuss the formation of phyllotactic patterns in the shoot apical meristem (SAM) of plants, where the spatial distribution of the phytohormone auxin determines phyllotaxis in a domain that is growing and changing in time. We assume that the concentration of auxin modifies the mechanical properties of the domain and that the mechanical stress field in the SAM orients the flux of auxin. To study this problem we propose a mechanism for pattern formation in growing domains with variable curvature. The dynamics of chemicals is modeled by a reaction-diffusion system that produces a three dimensional pattern of chemical concentrations that changes the stress field in the domain while growing. The growth process is modeled by a phase-field order parameter which determines the location of the boundaries of the domain. This field is coupled to the chemical concentration through a curvature term that affects the local mechanical stress in the domain. The local stress changes in turn modify the chemical patterns. Our model constitutes a useful and novel approach in theoretical biology, as many developmental processes in organisms seem to be affected by the changes of curvature, size, mechanical stress and other physical aspects. Several patterns seen in many plants are reproduced under certain conditions by our model.

The integrated stress response regulates BMP signalling through effects on translation

BackgroundDevelopmental pathways must be responsive to the environment. Phosphorylation of eIF2α enables a family of stress-sensing kinases to trigger the integrated stress response (ISR), which has pro-survival and developmental consequences. Bone morphogenetic proteins (BMPs) regulate multiple developmental processes in organisms from insects to mammals.ResultsHere we show in Drosophila that GCN2 antagonises BMP signalling through direct effects on translation and indirectly via the transcription factor crc (dATF4). Expression of a constitutively active GCN2 or loss of the eIF2α phosphatase dPPP1R15 impairs developmental BMP signalling in flies. In cells, inhibition of translation by GCN2 blocks downstream BMP signalling. Moreover, loss of d4E-BP, a target of crc, augments BMP signalling in vitro and rescues tissue development in vivo.ConclusionThese results identify a novel mechanism by which the ISR modulates BMP signalling during development.

Age-related epigenetic drift and phenotypic plasticity loss: implications in prevention of age-related human diseases.

Aging is considered as one of the most important developmental processes in organisms and is closely associated with global deteriorations of epigenetic markers such as aberrant methylomic patterns. This altered epigenomic state, referred to ‘epigenetic drift’, reflects deficient maintenance of epigenetic marks and contributes to impaired cellular and molecular functions in aged cells. Epigenetic drift-induced abnormal changes during aging are scantily repaired by epigenetic modulators. This inflexibility in the aged epigenome may lead to an age-related decline in phenotypic plasticity at the cellular and molecular levels due to epigenetic drift. This perspective aims to provide novel concepts for understanding epigenetic effects on the aging process and to provide insights into epigenetic prevention and therapeutic strategies for age-related human disease.

Effects of light and circadian clock on growth and chlorophyll accumulation of Nannochloropsis gaditana.

Circadian clocks synchronize various physiological, metabolic and developmental processes of organisms with specific phases of recurring changes in their environment (e.g. day and night or seasons). Here, we investigated whether the circadian clock plays a role in regulation of growth and chlorophyll (Chl) accumulation in Nannochloropsis gaditana, an oleaginous marine microalga which is considered as a potential feedstock for biofuels and for which a draft genome sequence has been published. Optical density (OD) of N.gaditana culture was monitored at 680 and 735nm under 12:12h or 18:6h light-dark (LD) cycles and after switching to continuous illumination in photobioreactors. In parallel, Chl fluorescence was measured to assess the quantum yield of photosystem II. Furthermore, to test if red- or blue-light photoreceptors are involved in clock entrainment in N.gaditana, some of the experiments were conducted by using only red or blue light. Growth and Chl accumulation were confined to light periods in the LD cycles, increasing more strongly in the first half than in the second half of the light periods. After switching to continuous light, rhythmic oscillations continued (especially for OD680 ) at least in the first 24h, with a 50% decrease in the capacity to grow and accumulate Chl during the first subjective night. Pronounced free-running oscillations were induced by blue light, but not by red light. In contrast, the photosystem II quantum yield was determined by light conditions. The results indicate interactions between circadian and light regulation of growth and Chl accumulation in N.gaditana.

Regulation of a Myb Transcription Factor by Cyclin-dependent Kinase 2 in Giardia lamblia

The protozoan Giardia lamblia parasitizes the human small intestine to cause diseases. It undergoes differentiation into infectious cysts by responding to intestinal stimulation. How the activated signal transduction pathways relate to encystation stimulation remain largely unknown. During encystation, genes encoding cyst wall proteins (CWPs) are coordinately up-regulated by a Myb2 transcription factor. Because cell differentiation is linked to cell cycle regulation, we tried to understand the role of cell cycle regulators, cyclin-dependent kinases (Cdks), in encystation. We found that the recombinant Myb2 was phosphorylated by Cdk-associated complexes and the levels of phosphorylation increased significantly during encystation. We have identified a putative cdk gene (cdk2) by searching the Giardia genome database. Cdk2 was found to localize in the cytoplasm with higher expression during encystation. Interestingly, overexpression of Cdk2 resulted in a significant increase of the levels of cwp gene expression and cyst formation. In addition, the Cdk2-associated complexes can phosphorylate Myb2 and the levels of phosphorylation increased significantly during encystation. Mutations of important catalytic residues of Cdk2 resulted in a significant decrease of kinase activity and ability of inducing cyst formation. Addition of a Cdk inhibitor, purvalanol A, significantly decreased the Cdk2 kinase activity and the levels of cwp gene expression and cyst formation. Our results suggest that the Cdk2 pathway may be involved in phosphorylation of Myb2, leading to activation of the Myb2 function and up-regulation of cwp genes during encystation. The results provide insights into the use of Cdk inhibitory drugs in disruption of Giardia differentiation into cysts.

Genome-Wide Deficiency Mapping of the Regions Responsible for Temporal Canalization of the Developmental Processes of Drosophila melanogaster

Developmental processes of organisms are programmed to proceed in a finely regulated manner and finish within a certain period of time depending on the ambient environmental conditions. Therefore, variation in the developmental period under controlled genetic and environmental conditions indicates innate instability of the developmental process. In this study, we aimed to determine whether a molecular machinery exists that regulates the canalization of the developmental period and, if so, to test whether the same mechanism also stabilizes a morphological trait. To search for regions that influence the instability of the developmental period, we conducted genome-wide deficiency mapping with 441 isogenic deficiency strains covering 65.5% of the Drosophila melanogaster genome. We found that 11 independent deficiencies significantly increased the instability of the developmental period and 5 of these also significantly increased the fluctuating asymmetry of wing shape although there was no significant correlation between the instabilities of developmental period and wing shape in general. These results suggest that canalization processes of the developmental period and morphological traits are at least partially independent. Our findings emphasize the potential importance of temporal variation in development as an indicator of developmental stability and canalization and provide a novel perspective for understanding the regulation of phenotypic variability.

Simulation of Developmental Process of Organism and Application to Structural Design

In the early processes of design called conceptual and preliminary design, diverse design ideas must be obtained under the constraint of unclear design conditions. Since ancient times, designers have been referred to form and structure of natural organism to create new artifacts. Design method referencing organisms could develop new designs and improve design capabilities. This paper describes a design system referencing emergent organism evolution, diversity, and environmental adaptation to obtain diverse design solutions. We simulate developmental process of organism, "induction" and "apical dominance" for diverse organism morphogenesis and propose form-generation system for obtaining diverse design solutions in a self-organizing manner using cellular automata. Generated organisms are adapted to the environment. We add a process in which forms are structurally adapted, optimizing diverse design ideas. To verify effectiveness proposal, we apply our proposal to the structural design of chairs. We discuss the effectiveness of our proposal applying organism morphogenesis for obtaining diverse design solutions.

A test of fluctuating asymmetry as a bioindicator of stress in antlered flies

Disturbances to the developmental processes of organisms produce phenotypic asymmetries. It has been hypothesized that populations subjected to sustained environmental stress will suffer greater developmental instability and, therefore, exhibit greater morphological asymmetry than healthy populations. Thus, sampling the average asymmetry of populations through time might be a useful indicator of the overall health of their corresponding habitat. This hypothesis was investigated using antler flies (Phytafmia spp.) in Papua New Guinea rainforests. The larval substrate of these flies is restricted to a few rainforest tree species found in primary forests. The prediction that fly populations in logging areas would exhibit greater asymmetry was tested by comparing fluctuating asymmetry (FA: small, random deviations from perfect symmetry) of fly populations in primary forest and logging areas, as well as from a single location across time. Only one (P. biarmala) of three species had significantly higher FA (according to a composite measure of wing venation) at logged sites than at intact forest sites, and the average FA decreased in a population of P. afcicornis over a 20-year period despite continuous logging in the area. Because some sample sizes were unavoidably small, a meta-analysis of combined effect sizes was performed and revealed a significant effect of habitat on FA across the species. Logging practices may impose stress on these flies as alleged, but if so the indication of the stress through FA levels was weak. Thus, reliance on this method as a monitoring tool for this environment should be considered with caution.

Emergent Design System for Obtaining Diverse Design Solutions in Structural Design

Conventional structural optimization methods are difficult to apply to the early process of design referred to as conceptual design, in which diverse design solutions are to be obtained. This paper describes a design method that obtains diverse design solutions. As a first step, a form-generation system that generates diverse forms is proposed. In this case, the diversity of organism is noted, and the form-generation method is referred to 'induction' and 'apical dominance' in the developmental process of organism. The proposed system, consisting of a generation process and an optimization process, is applied to the structural design of chairs, and the diversity of solutions is analyzed. As a result, it is shown that, as compared with conventional structural optimization methods, the proposed method obtains design solutions of adequate diversity. The results indicate the effectiveness of the proposed system for obtaining diverse design solutions.

Canonical and non-canonical Wnt signaling pathways in Caenorhabditis elegans: variations on a common signaling theme.

Wnt glycoproteins are signaling molecules that control a wide range of developmental processes in organisms ranging from the simple metazoan Hydra to vertebrates. Wnt signaling also plays a key role in the development of the nematode C. elegans, and is involved in cell fate specification and determination of cell polarity and cell migration. Surprisingly, the first genetic studies of Wnt signaling in C. elegans revealed major differences with the established (canonical) Wnt signaling pathways of Drosophila and vertebrates. Thus, the Wnt-dependent induction of endoderm in the early embryo and the specification of several asymmetric cell divisions during larval development are mediated by as yet novel Wnt signaling pathways that repress, rather than activate the TCF/LEF-1 transcription factor POP-1. Recently, however, it has been shown that, in addition to these divergent Wnt pathways, C. elegans also has a canonical Wnt pathway that converts POP-1 into an activator and controls the expression of several homeobox genes. Interestingly, these different Wnt pathways use distinct beta-catenins to control POP-1 function: the endoderm induction pathway requires the beta-catenin WRM-1 and parallel input from a mitogen-activated kinase (MAPK) pathway to downregulate POP-1, whereas the canonical Wnt pathway employs the beta-catenin BAR-1 to activate Wnt target gene expression.

328 生物の発生過程を模倣した自己組織型多様解導出システム(OS14-1 最適化の新展開)(OS14 最適化の理論と応用 : I.最適化の新展開と応用)

328 生物の発生過程を模倣した自己組織型多様解導出システム(OS14-1 最適化の新展開)(OS14 最適化の理論と応用 : I.最適化の新展開と応用)

Effects of heavy metals (Hg2+, cd2+, Pb2+) during the embryonic development of acridid grasshoppers (Insecta, caelifera)

Heavy metals present in the soil get differently accumulated in organisms and show different rates of toxicity at different stages of the life cycle of any organism living there. To see whether such toxicants get accumulated during the embryonic development and/or change the normal developmental processes of organisms exposed to heavy metals, freshly laid eggs and egg pods of two acridids, Aiolopus thalassinus and Eyprepocnemis plorans, were tested against different concentrations of Hg2+, Cd2+, and Pb2+. At increasing Hg2+ concentration in the substrate, an increased egg mortality and reduced nymphal hatching in A. thalassinus were observed, yet no change in the normal duration for embryonic development was noticed. A higher hatching rate of E. plorans nymphs than that of A. thalassinus could possibly be due to the higher tolerance, contributed by larger egg volume and thicker foam around the egg pods of the former. Treated concentrations of Hg2+ could be of sublethal (0.121 &mgr;g Hg2+/g substrate) to lethal (0.605 &mgr;g and more Hg2+/g substrate) doses. The mortality of eggs did not always increase with increasing substrate concentration of Cd2+ and Pb2+, and the hatching rates of both grasshopper species in many cases were even higher than that in the control. Still, lower accumulation factors of Cd2+ and Pb2+ than that of Hg2+ were found coupled with not increased mortality. The tested concentrations of Cd2+ and Pb2+ in the substrates, thus, could be of subacute doses. The embryonic development was found prolonged due to Cd2+ and Pb2+. During parallel egg and egg pod treatments, higher metal concentrations were found in not developed eggs than that in fresh nymphs hatching from the same substrates. This indicated the role of foam around the egg pods as "protective filter" against the toxic substances in the soil.

Multiple type-? transforming growth factors and their receptors

Type beta transforming growth factors are a group of homologous structurally related polypeptides that act on a wide variety of cell types to alter their proliferative and phenotypic properties. TGF-beta s form a group within a larger family of polypeptides that control developmental processes in organisms from humans to Drosophila. We have found that at least three distinct forms of TGF-beta are present in mammalian tissues. We have identified a family of cell surface glycoproteins that bind TGF-beta s with high affinity and specificity. Examination of the interactions between individual forms of TGF-beta and the individual TGF-beta receptor species has illustrated a complex pattern of ligand-receptor associations. Occupancy of a particular receptor type by TGF-beta can be correlated to the dictation of specific effects on cell proliferation and cell differentiation.