scholarly journals Regulated aggregative multicellularity in a close unicellular relative of metazoa

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Arnau Sebé-Pedrós ◽  
Manuel Irimia ◽  
Javier del Campo ◽  
Helena Parra-Acero ◽  
Carsten Russ ◽  
...  
Keyword(s):  
Life Cycle ◽  
Alternative Splicing ◽  
Splicing Regulation ◽  
Tissue Architecture ◽  
Genetic Changes ◽  
Aggregative Behavior ◽  
History Of

The evolution of metazoans from their unicellular ancestors was one of the most important events in the history of life. However, the cellular and genetic changes that ultimately led to the evolution of multicellularity are not known. In this study, we describe an aggregative multicellular stage in the protist Capsaspora owczarzaki, a close unicellular relative of metazoans. Remarkably, transition to the aggregative stage is associated with significant upregulation of orthologs of genes known to establish multicellularity and tissue architecture in metazoans. We further observe transitions in regulated alternative splicing during the C. owczarzaki life cycle, including the deployment of an exon network associated with signaling, a feature of splicing regulation so far only observed in metazoans. Our results reveal the existence of a highly regulated aggregative stage in C. owczarzaki and further suggest that features of aggregative behavior in an ancestral protist may had been co-opted to develop some multicellular properties currently seen in metazoans.

Rites of Passage

2018 ◽  
Author(s):  
Axel Michaels
Keyword(s):  
Life Cycle ◽  
Old Age ◽  
Sexual Maturity ◽  
Rites Of Passage ◽  
Life And Death ◽  
Transformational Process ◽  
Local Contexts ◽  
Vulnerable Community ◽  
History Of ◽  
The Individual

This chapter examines the classical Hindu life-cycle rites, the term saṃskāra and its history, and the main sources (Gṛhyasūtras and Dharma texts). It presents a history of the traditional saṃskāras and variants in local contexts, especially in Nepal. It describes prenatal, birth and childhood, initiation, marriage, old-age, death, and ancestor rituals. Finally, it analyzes the transformational process of these life-cycle rituals in the light of general theories on rites of passage. It proposes, in saṃskāras, man equates himself with the unchangeable and thus seems to counteract the uncertainty of the future, of life and death, since persons are confronted with their finite existence. For evidently every change, whether social or biological, represents a danger for the cohesion of the vulnerable community of the individual and society. These rituals then become an attempt of relegating the effects of nature or of mortality: birth, teething, sexual maturity, reproduction, and dying.

scholarly journals Nova Regulates GABAA Receptor γ2 Alternative Splicing via a Distal Downstream UCAU-Rich Intronic Splicing Enhancer

2003 ◽  
Vol 23 (13) ◽  
pp. 4687-4700 ◽  
Author(s):  
B. Kate Dredge ◽  
Robert B. Darnell
Keyword(s):  
Alternative Splicing ◽  
Rna Binding ◽  
Splice Acceptor Site ◽  
Acceptor Site ◽  
Splicing Regulation ◽  
Globin Genes ◽  
Enhancer Element ◽  
Intronic Splicing Enhancer ◽  
Splicing Enhancer

ABSTRACT Nova is a neuron-specific RNA binding protein targeted in patients with the autoimmune disorder paraneoplastic opsoclonus-myoclonus ataxia, which is characterized by failure of inhibition of brainstem and spinal motor systems. Here, we have biochemically confirmed the observation that splicing regulation of the inhibitory GABAA receptor γ2 (GABAARγ2) subunit pre-mRNA exon E9 is disrupted in mice lacking Nova-1. To elucidate the mechanism by which Nova-1 regulates GABAARγ2 alternative splicing, we systematically screened minigenes derived from the GABAARγ2 and human β-globin genes for their ability to support Nova-dependent splicing in transient transfection assays. These studies demonstrate that Nova-1 acts directly on GABAARγ2 pre-mRNA to regulate E9 splicing and identify an intronic region that is necessary and sufficient for Nova-dependent enhancement of exon inclusion, which we term the NISE (Nova-dependent intronic splicing enhancer) element. The NISE element (located 80 nucleotides upstream of the splice acceptor site of the downstream exon E10) is composed of repeats of the sequence YCAY, consistent with previous studies of the mechanism by which Nova binds RNA. Mutation of these repeats abolishes binding of Nova-1 to the RNA in vitro and Nova-dependent splicing regulation in vivo. These data provide a molecular basis for understanding Nova regulation of GABAARγ2 alternative splicing and suggest that general dysregulation of Nova's splicing enhancer function may underlie the neurologic defects seen in Nova's absence.

Sequence variation and evolution of nuclear DNA in man and the primates

1981 ◽  
Vol 292 (1057) ◽  
pp. 133-142 ◽  
Keyword(s):  
Dna Sequence ◽  
Sequence Variation ◽  
Nuclear Dna ◽  
Sequence Divergence ◽  
Gene Arrangement ◽  
Human Populations ◽  
Genetic Changes ◽  
Detailed Structural Analysis ◽  
Dna Sequence Variation ◽  
History Of

Recent advances in nucleic acid technology have facilitated the detection and detailed structural analysis of a wide variety of genes in higher organisms, including those in man. This in turn has opened the way to an examination of the evolution of structural genes and their surrounding and intervening sequences. In a study of the evolution of haemoglobin genes and neighbouring sequences in man and the primates, we have investigated gene arrangement and DNA sequence divergence both within and between species ranging from Old World monkeys to man. This analysis is beginning to reveal the evolutionary constraints that have acted on this region of the genome during primate evolution. Furthermore, DNA sequence variation, both within and between species, provides, in principle, a novel and powerful method for determining inter-specific phylogenetic distances and also for analysing the structure of present-day human populations. Application of this new branch of molecular biology to other areas of the human genome should prove important in unravelling the history of genetic changes that have occurred during the evolution of man.

The reproduction and larval development of Nereis fucata (Savigny)

1959 ◽  
Vol 38 (1) ◽  
pp. 65-80 ◽  
Author(s):  
J. B. Brown-Gilpin
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Experimental Methods ◽  
Point Of View ◽  
Hermit Crabs ◽  
Special Importance ◽  
Reproductive Patterns ◽  
Complete Life Cycle ◽  
History Of ◽  
The Many

The wide variety of reproductive patterns and behaviour in the many species of Nereidae already studied clearly justifies further research. But the life history of Nereis fucata (Savigny) is not only of interest from the comparative point of view. Its commensal habit (it occurs within shells occupied by hermit crabs) immediately gives it a special importance. This alone warrants a detailed study, particularly as no commensal polychaete has yet been reared through to metamorphosis and settlement on its host (Davenport, 1955; Davenport & Hickok, 1957). The numerous interesting problems which arise, and the experimental methods needed to study them, are, however, beyond the range of a paper on nereid development. It is therefore proposed to confine the present account to the reproduction and development up to the time when the larvae settle on the bottom. The complete life cycle, the mechanism of host-adoption, and related topics, will be reported in later papers.

History of microfinance in Bangladesh: A life cycle theory approach

2017 ◽  
Vol 61 (4) ◽  
pp. 703-733 ◽  
Author(s):  
Md Aslam Mia ◽  
Hwok-Aun Lee ◽  
VGR Chandran ◽  
Rajah Rasiah ◽  
Mahfuzur Rahman
Keyword(s):  
Life Cycle ◽  
Theory Approach ◽  
Life Cycle Theory ◽  
History Of

scholarly journals A STUDY OF THE LIFE HISTORY OF TRICHOBILHARZIA CAMERONI SP. NOV. (FAMILY SCHISTOSOMATIDAE)

1953 ◽  
Vol 31 (4) ◽  
pp. 351-373 ◽  
Author(s):  
Liang-Yu Wu
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Room Temperature ◽  
Migratory Birds ◽  
Local Infection ◽  
Domestic Ducks ◽  
Ottawa River ◽  
Daughter Sporocyst ◽  
Physa Gyrina ◽  
History Of

A cause of swimmer's itch in the lower Ottawa River is Trichobilharzia cameroni sp. nov. Its life cycle has been completed experimentally in laboratory-bred snails and in canaries and ducks, and the various stages are described. The eggs are spindle-shaped. The sporocysts are colorless and tubular. Mother sporocysts become mature in about a week. The younger daughter sporocyst is provided with spines on the anterior end and becomes mature in about three weeks. The development in the snail requires from 28 to 35 days. A few cercariae were found to live for up to 14 days at 50 °C., although their life at 16° to 18 °C. was about four days. Cercariae kept at room temperature for 60 to 72 hr. were found infective. The adults become mature in canaries and pass eggs in about 12 to 14 days. Physa gyrina is the species of snail naturally infected. It was found in one case giving off cercariae for five months after being kept in the laboratory. Domestic ducks were found to become infected until they were at least four months old, with the parasites developing to maturity in due course; no experiments were made with older ducks. Furthermore, miracidia were still recovered from the faeces four months after the duck had been experimentally infected, and it is suggested that migratory birds are the source of the local infection.

Sign in / Sign up

Export Citation Format

Share Document