CYTOLOGICAL STUDIES OF THE DEVELOPMENT OF METAPHASE I IN HYBRIDS BETWEEN TRITICUM TIMOPHEEVI ZHUK. AND T. DURUM DESF.

1961 ◽  
Vol 39 (1) ◽  
pp. 81-108 ◽  
Author(s):  
E. B. Wagenaar
Keyword(s):  
Late Stage ◽  
Developmental Stages ◽  
Progressive Increase ◽  
Cell Populations ◽  
Equatorial Plate ◽  
Triticum Timopheevi ◽  
Late Stages ◽  
I Cells ◽  
Metaphase I

In two hybrids between Triticum timopheevi Zhuk. and T. durum Desf., which have irregular meioses, metaphase I was subdivided into four developmental stages, early, medium, late, and very late. This subdivision was based on the presence in the anthers of other stages that occurred together with metaphase I. It was then discovered that in metaphase I cell populations there was a progressive increase of univalents from the early and medium stages to the very late stage. This phenomenon can be explained on the assumption that metaphase I is of shorter duration in the less irregular cells which pass into anaphase I earlier than the more irregular cells. As a consequence of this developmental phenomenon at metaphase I, the anaphase I and telophase I cells in the late anthers contained fewer lagging chromosomes than the anaphase I and telophase I cells in the very late anthers. Despite these numerical differences, the degrees of lagging were remarkably similar in both stages; approximately 70% of these univalents lagged at late and very late stages in both hybrids.During metaphase I many univalents of the irregular cells moved towards the equatorial plate, became oriented, and lagged at anaphase I and telophase I. It was found that the univalents of the least irregular cells accumulated somewhat faster at the plates than those of the more irregular cells.Considering the relationships between all of the available data, the hypothesis is advanced that when a certain number of univalents have accumulated at the equatorial plate a state of equilibrium is established and anaphase I is initiated. On the basis of this hypothesis an explanation of the trends observed at metaphase I is given.

Adolescent Development and Capacity Building

2018 ◽  
Author(s):  
Esther F. Akinsola ◽  
Anne C. Petersen
Keyword(s):  
Capacity Building ◽  
Adolescent Development ◽  
Developmental Stages ◽  
Decision Makers ◽  
Developmental Tasks ◽  
Cultural Contexts ◽  
Global Policy ◽  
Development Capacity ◽  
The Social ◽  
Late Stages

This chapter describes adolescent development within the context of capacity building, reviews the global adolescent capacity-building initiatives, and provides a link between developmental tasks of adolescence and capacity building. It highlights the importance of incorporating assessment of adolescents’ capacity-building needs at individual, community, and organizational levels into global policy and programs and suggests effective approaches to building adolescent development capacity that include adopting the “stage–environment–fit,” in which stage represents the developmental stages (early, middle, late stages) of adolescents and emphasizes developmental tasks of adolescence, while environment represents the social and cultural contexts in which the adolescents live. That adolescents need to be engaged as planners, decision-makers, and participants in programs that build their capacity and translation of global policies into policies of governments is emphasized.

Ultrastructural Localization of Intracellular Calcium During Spermatogenesis of Sterlet (Acipenser ruthenus)

2016 ◽  
Vol 22 (6) ◽  
pp. 1155-1161 ◽  
Author(s):  
Amin Golpour ◽  
Martin Pšenička ◽  
Hamid Niksirat
Keyword(s):  
Intracellular Calcium ◽  
Developmental Stages ◽  
Physiological Function ◽  
Male Gamete ◽  
Ultrastructural Localization ◽  
Acrosomal Vesicle ◽  
Acipenser Ruthenus ◽  
Calcium Deposits ◽  
Late Stages ◽  
Sterlet Acipenser Ruthenus

AbstractCalcium regulates many intracellular events such as growth and differentiation during different stages of gamete development. The aim of this study was to localize and quantify the intracellular distribution of calcium during different developmental stages of spermatogenesis in sterlet, Acipenser ruthenus, using a combined oxalate–pyroantimonate technique. The distribution of calcium was described in spermatogonium, spermatocyte, spermatid, and spermatozoon stages. In the spermatogonium and spermatocyte, calcium deposits were mainly localized in the nucleus and cytoplasm. The spermatid had calcium in the nucleus, developing acrosomal vesicle, and cytoplasm. Intracellular calcium transformed from scattered deposits in spermatogonia and spermatocyte stages into an unbound form in spermatid and the spermatozoon. The proportion of area covered by calcium increased significantly (p<0.05) from early to late stages of spermatogenesis. The largest proportion of area covered by calcium was observed in the nucleus of the spermatozoon. In conclusion, although most of the intracellular calcium is deposited in limited areas of the spermatogonium and spermatocyte, it is present an unbound form in the larger area of spermatids and spermatozoa which probably reflects changes in its physiological function and homeostasis during the process of male gamete production in spermatogenesis.

The application of aqueous two-phase partition to the study of chick limb mesenchymal diversification

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 267-275
Author(s):  
C. P. Cottrill ◽  
Paul T. Sharpe ◽  
Lewis Wolpert
Keyword(s):  
Pattern Formation ◽  
Limb Development ◽  
Developmental Stages ◽  
Proximal Region ◽  
Limb Bud ◽  
Cell Populations ◽  
Two Phase ◽  
Phase Partition ◽  
Surface Character ◽  
Two Phase Partition

A technique which identifies cells differing in surface character, aqueous two-phase partition using thin-layer countercurrent distribution (TLCCD), has been used to study differentiation and pattern formation in the developing chick limb bud. The TLCCD profiles of cell populations, derived from various regions of morphologically undifferentiated mesenchyme from three different stages of limb development, have been compared. At no stage, or location, has the population been found to be homogeneous. Cells from progress zones and more proximal regions could all be resolved into several populations. The populations from progress zones at three different developmental stages were qualitatively similar but differed in the proportions of cells in each. The most striking differences in cell populations were those obtained from the most proximal region of the limb, closest to the flank, which represents the developmentally most advanced region.

Genesis of Alcohol-Induced Craniofacial Dysmorphism

2005 ◽  
Vol 230 (6) ◽  
pp. 366-375 ◽  
Author(s):  
Kathleen K. Sulik
Keyword(s):  
Mouse Model ◽  
Developmental Stages ◽  
Expression Patterns ◽  
Alcohol Exposure ◽  
The United States ◽  
Maternal Blood ◽  
Resistant Cell ◽  
Embryonic Cell ◽  
Cell Populations ◽  
Craniofacial Dysmorphism

The initial diagnosis of fetal alcohol syndrome (FAS) in the United States was made because of the facial features common to the first cohort of patients. This article reviews the development of an FAS mouse model whose craniofacial features are remarkably similar to those of affected humans. The model is based on short-term maternal treatment with a high dosage of ethanol at stages of pregnancy that are equivalent to Weeks 3 and 4 of human gestation. At these early stages of development, alcohol’s insult to the developing face is concurrent with that to the brain, eyes, and inner ear. That facial and central nervous system defects consistent with FAS can be induced by more “realistic” alcohol dosages as illustrated with data from an oral alcohol intake mouse model in which maternal blood alcohol levels do not exceed 200 mg/dl. The ethanol-induced pathogenesis involves apoptosis that occurs within 12 hrs of alcohol exposure in selected cell populations of Day 7, 8, and 9 mouse embryos. Experimental evidence from other species also shows that apoptosis underlies ethanol-induced malformations. With knowledge of sensitive and resistant cell populations at specific developmental stages, studies designed to identify the basis for these differing cellular responses and, therefore, to determine the primary mechanisms of ethanol’s teratogenesis are possible. For example, microarray comparisons of sensitive and resistant embryonic cell populations have been made, as have in situ studies of gene expression patterns in the populations of interest. Studies that illustrate agents that are effective in diminishing or exacerbating ethanol’s teratogenesis have also been helpful in determining mechanisms. Among these agents are antioxidants, sonic hedgehog protein, retinoids, and the peptides SAL and NAP.

scholarly journals Tip60 protects against amyloid-β peptide-induced transcriptomic alterations via different modes of action in early versus late stages of neurodegenerative progression

2020 ◽  
Author(s):  
Haolin Zhang ◽  
Bhanu Chandra Karisetty ◽  
Akanksha Bhatnagar ◽  
Ellen M. Armour ◽  
Mariah Beaver ◽  
...  
Keyword(s):  
Cell Death ◽  
Cognitive Deficits ◽  
Late Stage ◽  
Neurodegenerative Disorder ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Amyloid Β Peptide ◽  
Histone Deacetylase 2 ◽  
Age Related ◽  
Late Stages

ABSTRACTAlzheimer’s disease (AD) is an age-related neurodegenerative disorder hallmarked by amyloid-β (Aβ) plaque accumulation, neuronal cell death, and cognitive deficits that worsen during disease progression. Histone acetylation dysregulation, caused by an imbalance between reduced histone acetyltransferases (HAT) Tip60 and increased histone deacetylase 2 (HDAC2) levels, can directly contribute to AD pathology. However, whether such AD-associated neuroepigenetic alterations occur in response to Aβ peptide production and can be protected against by increasing Tip60 levels over the course of neurodegenerative progression remains unknown. Here we profile Tip60 HAT/HDAC2 dynamics and transcriptome-wide changes across early and late stage AD pathology in the Drosophila brain produced solely by human amyloid-β42. We show that early Aβ42 induction leads to disruption of Tip60 HAT/HDAC2 balance during early neurodegenerative stages preceding Aβ plaque accumulation that persists into late AD stages. Correlative transcriptome-wide studies reveal alterations in biological processes we classified as transient (early-stage only), late-onset (late-stage only), and constant (both). Increasing Tip60 HAT levels in the Aβ42 fly brain protects against AD functional pathologies that include Aβ plaque accumulation, neural cell death, cognitive deficits, and shorter life-span. Strikingly, Tip60 protects against Aβ42-induced transcriptomic alterations via distinct mechanisms during early and late stages of neurodegeneration. Our findings reveal distinct modes of neuroepigenetic gene changes and Tip60 neuroprotection in early versus late stages in AD that can serve as early biomarkers for AD, and support the therapeutic potential of Tip60 over the course of AD progression.

scholarly journals Plant Developmental Stage Drives the Differentiation in Ecological Role of Plant Bacterial and Fungal Microbiomes

2021 ◽  
Author(s):  
Chao Xiong ◽  
Brajesh K. Singh ◽  
Ji-Zheng He ◽  
Yan-Lai Han ◽  
Pei-Pei Li ◽  
...  
Keyword(s):  
Developmental Stage ◽  
Plant Development ◽  
Late Stage ◽  
Developmental Stages ◽  
Early Stage ◽  
Alpha Diversity ◽  
Microbial Interactions ◽  
Disease Suppression ◽  
Fungal Communities ◽  
Ecological Role

Abstract BackgroundPlants live with diverse microbial communities which profoundly affect multiple facets of host performance such as nutrition acquisition, disease suppression and productivity, but if and how host development impacts the assembly, functions and microbial interactions of crop microbiomes are poorly understood. Here we examined both bacterial and fungal communities across soils (rhizosphere and bulk soil), plant epiphytic and endophytic niches (phylloplane, rhizoplane, leaf and root endosphere), and plastic leaf of fake plant (representing environment-originating microbes) at three developmental stages of maize at two contrasting sites, and further explored the potential function of phylloplane microbiomes based on metagenomics.ResultsOur results suggested that plant developmental stage had a much stronger influence on the microbial diversity, composition and interkingdom networks in plant compartment niches than in soils, with the strongest effect in the phylloplane. Air (represented by fake plants) was an important source of phylloplane microbiomes which were co-shaped by both plant development and seasonal environmental factors. Further, we demonstrated that bacterial and fungal communities in plant compartment niches exhibited contrasting response to host developmental stages, with higher alpha diversity and stronger deterministic assembly within bacterial microbiomes at the early stage but a similar pattern within mycobiomes at the late stage. Moreover, we found that bacterial taxa played a more important role in microbial interkingdom network and crop yield prediction at the early stage, while fungal taxa did so at the late stage. Metagenomic analyses further indicated that phylloplane microbiomes possessed higher functional diversity and functional genes involved in nutrient provision and disease resistance at the early stage than the late stage. ConclusionsOur results suggest that host developmental stage profoundly influences plant microbiome assembly and functions, and the bacterial and fungal microbiomes take a differentiated ecological role at different plant development stages. This study provides empirical evidence for host exerting strong effect on plant microbiomes by deterministic selection to meet the physiological requirement of plant developmental stages. These findings have implications for the development of future tools to manipulate microbiome for sustainable increase in primary productivity.

scholarly journals Diversity and Distribution of Mid- to Late-Stage Phyllosomata of Spiny and Slipper Lobsters (Decapoda: Achelata) in the Mexican Caribbean

Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 485
Author(s):  
Rubén Muñoz de Muñoz de Cote-Hernández ◽  
Patricia Briones-Fourzán ◽  
Cecilia Barradas-Ortiz ◽  
Fernando Negrete-Soto ◽  
Enrique Lozano-Álvarez
Keyword(s):  
Late Stage ◽  
Short Term ◽  
Planktonic Larva ◽  
Assemblage Composition ◽  
Term Retention ◽  
Mexican Caribbean ◽  
Dominant Feature ◽  
Panulirus Guttatus ◽  
Late Stages ◽  
Multiple Stages

Achelata (Palinuridae and Scyllaridae) have a flat, transparent, long-lived planktonic larva called phyllosoma, which comprises multiple stages and has a duration from a few weeks (some scyllarids) to >20 months (some palinurids). The larval development of many Achelata occurs in oceanic waters, where conventional plankton nets usually collect the early- to mid-stages but not the later stages, which remain poorly known. We examined the diversity and distribution of mid- and late-stage phyllosomata in the oceanic waters of the Mexican Caribbean, where the swift Yucatan Current is the dominant feature. The plankton samples were collected at night with a large mid-water trawl in autumn 2012 (55 stations) and spring 2013 (34 stations). In total, we obtained 2599 mid- and late-stage phyllosomata (1742 in autumn, 857 in spring) of five palinurids (Panulirus argus, Panulirus guttatus, Panulirus laevicauda, Palinurellus gundlachi, Justitia longimana) and three scyllarids (Parribacus antarcticus, Scyllarides aequinoctialis, Scyllarus chacei). Overall, the mid-stages were ~2.5 times as abundant as the late stages. The palinurids far outnumbered the scyllarids, and P. argus dominated over all the other species, followed at a distance by P. guttatus. The densities of all the species were generally low, with no clear spatial pattern, and the phyllosomata assemblage composition greatly overlapped between seasons. These results suggest the extensive mixing of the organisms entrained in the strong Yucatan Current, which clearly favors the advection of the phyllosomata in this region despite the presence of some local sub-mesoscale features that may favor short-term retention.

Tail formation as a continuation of gastrulation: the multiple cell populations of the Xenopus tailbud derive from the late blastopore lip

Development ◽  
1993 ◽  
Vol 119 (4) ◽  
pp. 991-1004 ◽  
Author(s):  
L.K. Gont ◽  
H. Steinbeisser ◽  
B. Blumberg ◽  
E.M. de Robertis
Keyword(s):  
Cell Populations ◽  
Fate Map ◽  
Stages Of Development ◽  
Gene Markers ◽  
Distinct Cell ◽  
Multiple Cell ◽  
Organizer Activity ◽  
Dorsal Cells ◽  
Late Stages ◽  
Lines Of Evidence

Three lines of evidence suggest that tail formation in Xenopus is a direct continuation of events initiated during gastrulation. First, the expression of two gene markers, Xbra and Xnot2, can be followed from the blastopore lip into distinct cell populations of the developing tailbud. Second, the tip of the tail retains Spemann's tail organizer activity until late stages of development. Third, lineage studies with the tracer DiI indicate that the cells of the late blastopore are fated to form specific tissues of the tailbud, and that intercalation of dorsal cells continues during tail elongation. In particular, the fate map shows that the tip of the tail is a direct descendant of the late dorsal blastopore lip. Thus, the tailbud is not an undifferentiated blastema as previously thought, but rather consists of distinct cell populations which arise during gastrulation.

Distribution of acetylcholinesterase activity during the development of cysticercoids of Hymenolepis diminuta (Cestoda)

2006 ◽  
Vol 51 (2) ◽  
Author(s):  
Tadeusz Moczoń ◽  
Agnieszka Świetlikowska
Keyword(s):  
Nervous System ◽  
Developmental Stages ◽  
Acetylcholinesterase Activity ◽  
Hymenolepis Diminuta ◽  
Internal Wall ◽  
Early Developmental Stages ◽  
Early Developmental ◽  
Late Stages ◽  
Cyst Cavity ◽  
Developing Nervous System

AbstractThe distribution of acetylcholinesterase (AChE) in oncospheres and developing cysticercoids of Hymenolepis diminuta was examined. The enzyme was localized in the nervous system and in some non-nerve cells of these larvae. In oncospheres AChE was detected in hook muscles and in the binucleated medullar center that is known to enclose two neurons. At early developmental stages of the cysticercoids the enzyme was localized in the post-oncospheral hook muscles and in subtegumental muscle fibers of the cercomer. At medium and late stages of development the activity of AChE was detected in the developing nervous system and in two and, subsequently, in four populations of cells, which gradually spread over the whole internal wall of the cyst, thus forming a thin multilayer AChE-positive lining of the cyst cavity. Following withdrawal of the scolex the lining separates the parenchyma of the turned neck from the cyst tissues and remains AChE-positive during the whole life of the parasite, i.e. up to the death of the infected host. The role played by non-neural AChE associated with the cyst cavity lining is unknown, but seems to regulate both the transport of nutrients and minerals into the scolex and waste substances in the opposite direction.

THE ULTRASTRUCTURE OF KINETOCHORES OF UNPAIRED CHROMOSOMES IN A WHEAT HYBRID

1973 ◽  
Vol 15 (4) ◽  
pp. 801-806 ◽  
Author(s):  
E. B. Wagenaar ◽  
D. F. Bray
Keyword(s):  
Sister Chromatid ◽  
Metaphase Plate ◽  
Polar Regions ◽  
Equatorial Plate ◽  
Univalent Chromosome ◽  
Wheat Hybrid ◽  
Opposite Pole ◽  
Kinetochore Region ◽  
Metaphase I

The kinetochore region of unpaired chromosomes (univalents) consists of two kinetochores, each belonging to a sister chromatid, that are located adjacent to one another on the surface of the univalent chromosome. This condition results in a movement by the univalent towards one of the polar regions at the onset of metaphase I. Once arrived in this region, one of the sister kinetochores obtains attachments of microtubules from the opposite pole. This results in a gradual return of the univalent to the equatorial plate, where it reaches an equilibrium. The sister kinetochores remain adjacent during the movement, but once arrived at the metaphase plate they develop a typical mitotic appearance, in which the sister kinetochores have opposite positions on the chromosomes.

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