The life history and ecology of the snow alga Chloromonas polyptera comb. nov. (Chlorophyta, Volvocales)

1983 ◽  
Vol 61 (9) ◽  
pp. 2416-2429 ◽  
Author(s):  
Ronald W. Hoham ◽  
John E. Mullet ◽  
Stephen C. Roemer
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Laboratory Observation ◽  
Vegetative Cells ◽  
Snow Algae ◽  
Algal Succession ◽  
Snow Alga ◽  
Low Levels ◽  
Increasing Temperature ◽  
First Time

Snow algae previously designated as Carteria nivale, Scotiella polyptera, S. polyptera var. polimantii, and S. polyptera var. magellanica were found to be developmental stages of the zygote of Chloromonas polyptera comb. nov. Five species of Scotiella from snow have now been identified as zygotes of different specis of Chloromonas. In this life cycle, biflagellate vegetative cells, zoospores, gametes, and sexual reproduction are reported for the first time. The different forms of the zygote have been reported previously in the literature from several parts of the world, but have been misinterpreted as several distinct taxa of snow algae. The stages in the life cycle of Chloromonas polyptera occur in old, rapidly melting snowbanks, usually less than 30 cm deep. In the same snowbanks, zygotes of C. polyptera germinate later than those reported for Chloromonas nivalis, Chloromonas brevispina, and Chloromonas pichinchae indicating the occurrence of algal succession. Higher light intensity and a more saturated snowbank appear necessary for germination of zygotes of C. polyptera when compared with other species of Chloromonas found in snow. Low levels of carbon dioxide in snow may be limiting for growth of C. polyptera and vegetative cells are sensitive to increasing temperature as observed through laboratory observation. Freezing does not appear to initiate meiosis in the zygotes of C. polyptera as reported for other Volvocalean algae found in snow.

scholarly journals Ultrastructure of Lobosphaera reniformis (Watanabe) Komárek et Fott (Chlorellales) from King George Island, South Shetland Islands, Antarctica

2014 ◽  
Vol 63 (2) ◽  
pp. 205-210 ◽  
Author(s):  
A. Massalski ◽  
T. Mrozińska ◽  
M. Olech
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
South Shetland Islands ◽  
King George Island ◽  
Vegetative Cells ◽  
Shetland Islands ◽  
Complete Life Cycle ◽  
Laboratory Cultures ◽  
First Time

<i>Lobosphaera reniformis</i> (Wat.) Kom. et Fott (=<i>Chlorella reniformis</i> Wat.) so far known only from Japan, and Papua Island, was for the first time found in Antarctica (King George Island, South Shetland Islands). In laboratory cultures a complete life cycle was obtained, and most of its stages were followed by the electron microscopy. Reproduction is by morphologically different autospores. In some large vegetative cells two Golgi apparatuses lying side by side were observed.

scholarly journals Life cycle of Early Cambrian microalgae from theSkiagia-plexus acritarchs

2010 ◽  
Vol 84 (2) ◽  
pp. 216-230 ◽  
Author(s):  
Małgorzata Moczydłowska
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Biological Species ◽  
Complex Life Cycle ◽  
Early Cambrian ◽  
Closely Related Species ◽  
Vegetative Cells ◽  
Depositional Settings ◽  
Sexual Generation ◽  
Sheath Structure

Light microscopy studies on new materials and museum collections of early Cambrian organic-walled microfossils, informally called acritarchs, provide the observations on phenetic features that permit a comparison to certain Modern microalgae and the recognition of various developmental stages in their life cycle. the microfossils derive from various depositional settings in Estonia, Australia, Greenland, Sweden, and Poland. the exceptionally preserved microfossils reveal the internal body within the vesicle, the endocyst, and the process of releasing the endocyst from the cyst. Vegetative cells, cysts, and endocysts are distinguished, and the hypothetical reconstruction of a complex life cycle with the alternation of sexual and asexual generations is proposed. Acritarchs from theSkiagia-plexus are cysts, and likely zygotes in the sexual generation, which periodically rested as “benthic plankton.” Some microfossils of theLeiosphaeridia-plexus that are inferred to be vegetative cells were planktonic and probably haplobiontic. These form-taxa may belong to a single biological species, or a few closely related species, and represent the developmental stages and alternating generations in a complex life cycle that is expressed by polymorphic, sphaero- and acanthomorphic acritarchs. the morphological resemblance and diagnostic cell wall ultrastructure with the trilaminar sheath structure known from earlier studies suggest that the early Cambrian microfossils are the ancestral representatives and/or early lineages to the Modern class Chlorophyceae and the orders Volvocales and Chlorococcales.

scholarly journals The morphology of the immature stages of Squamapion atomarium (Kirby, 1808) (Coleoptera, Brentidae) and notes on its life cycle

ZooKeys ◽  
2019 ◽  
Vol 892 ◽  
pp. 103-120
Author(s):  
Krzysztof Pawlęga ◽  
Jacek Łętowski ◽  
Ewelina Szwaj ◽  
Tomasz Gosławski
Keyword(s):  
Life Cycle ◽  
Body Size ◽  
Developmental Stages ◽  
Morphological Features ◽  
Morphological Data ◽  
Immature Stages ◽  
Head Shape ◽  
Mature Larva ◽  
Development Cycle ◽  
First Time

The immature stages (egg, mature larva and pupa) of Squamapion atomarium (Kirby, 1808), as well as its development cycle and the phenology of its developmental stages, are described for the first time. The larva and pupa of S. atomarium have typical morphological features of the subfamily Apioninae. Morphological data on the immature stages were compared with the only fully described Squamapion species, S. elongatum (Germar, 1817). The larvae of the two species differ in body size and shape, head shape, setae length, the chaetotaxy of the mouthparts, and individual types of setae on the pronotum and thorax. In the case of the pupa, there are also differences in body size and in the type of setae and chaetotaxy of the head, pronotum, metanotum and abdomen.

Timing of the appearance of ubiquitinated histones in developing new macronuclei of Tetrahymena thermophila

1991 ◽  
Vol 69 (1) ◽  
pp. 66-71 ◽  
Author(s):  
James R. Davie ◽  
Rueyling Lin ◽  
C. David Allis
Keyword(s):  
Life Cycle ◽  
Western Blotting ◽  
Vegetative Growth ◽  
Tetrahymena Thermophila ◽  
Ciliated Protozoan ◽  
Active Chromatin ◽  
Somatic Nucleus ◽  
Vegetative Cells ◽  
Low Levels

Vegetative cells of the ciliated protozoan Tetrahymena thermophila contain a transcriptionally active macronucleus and a transcriptionally inert micronucleus. During vegetative growth, macronuclear histones H2A and H2B and micronuclear H2A are ubiquitinated. Despite differences in function, macro- and micro-nuclei are related. During conjugation (the sexual phase of the life cycle in Tetrahymena), postzygotic division products of micronuclei give rise to new micro- and macro-nuclei. Using an anti-ubiquitin antibody in Western blotting experiments, we determined the levels of ubiquitinated histones in new macro- and micro-nuclei at various times during conjugation. Very soon after the second postzygotic division (approximately 8 h) when new macronuclei begin to synthesize RNA, ubiquitinated H2B and polyubiquitinated H2A are present. At this time micronuclei have only low levels of ubiquitinated H2A. During later stages of conjugation (15 h), the level of polyubiquitinated H2A decreases, while ubiquitinated H2B increases in developing new macronuclei, attaining levels of ubiquitinated H2B approaching that of parental macronuclei. Ubiquitinated histones are not detectable in the 15-h micronuclei. These results show that ubiquitination of H2B coincides with the transformation of an inert germinal nucleus into that of a transcriptionally active somatic nucleus, suggesting that ubiquitinated H2B has a role in maintaining the transcriptionally active chromatin state.Key words: histone ubiquitination, Tetrahymena thermophila, chromatin, transcription.

scholarly journals Probing the floral developmental stages, bisexuality and sex reversions in castor (Ricinus communis L.)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sujatha Thankeswaran Parvathy ◽  
Amala Joseph Prabakaran ◽  
Thadakamalla Jayakrishna
Keyword(s):  
Developmental Stages ◽  
Ricinus Communis ◽  
Sex Expression ◽  
Pistil Abortion ◽  
Ricinus Communis L ◽  
Sex Reversion ◽  
Stage 4 ◽  
Meristem Development ◽  
Male Specific ◽  
First Time

AbstractCastor (Ricinus communis L) is an ideal model species for sex mechanism studies in monoecious angiosperms, due to wide variations in sex expression. Sex reversion to monoecy in pistillate lines, along with labile sex expression, negatively influences hybrid seed purity. The study focuses on understanding the mechanisms of unisexual flower development, sex reversions and sex variations in castor, using various genotypes with distinct sex expression pattern. Male and female flowers had 8 and 12 developmental stages respectively, were morphologically similar till stage 4, with an intermediate bisexual state and were intermediate between type 1 and type 2 flowers. Pistil abortion was earlier than stamen inhibition. Sex alterations occurred at floral and inflorescence level. While sex-reversion was unidirectional towards maleness via bisexual stage, at high day temperatures (Tmax > 38 °C), femaleness was restored with subsequent drop in temperatures. Temperature existing for 2–3 weeks during floral meristem development, influences sexuality of the flower. We report for first time that unisexuality is preceded by bisexuality in castor flowers which alters with genotype and temperature, and sex reversions as well as high sexual polymorphisms in castor are due to alterations in floral developmental pathways. Differentially expressed (male-abundant or male-specific) genes Short chain dehydrogenase reductase 2a (SDR) and WUSCHEL are possibly involved in sex determination of castor.

scholarly journals Malaria parasites both repress host CXCL10 and use it as a cue for growth acceleration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yifat Ofir-Birin ◽  
Hila Ben Ami Pilo ◽  
Abel Cruz Camacho ◽  
Ariel Rudik ◽  
Anna Rivkin ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Cerebral Malaria ◽  
Survival Strategy ◽  
Parasitic Disease ◽  
Malaria Parasites ◽  
Sensing System ◽  
Rich Domain ◽  
Cargo Delivery ◽  
Low Levels

AbstractPathogens are thought to use host molecular cues to control when to initiate life-cycle transitions, but these signals are mostly unknown, particularly for the parasitic disease malaria caused by Plasmodium falciparum. The chemokine CXCL10 is present at high levels in fatal cases of cerebral malaria patients, but is reduced in patients who survive and do not have complications. Here we show a Pf ‘decision-sensing-system’ controlled by CXCL10 concentration. High CXCL10 expression prompts P. falciparum to initiate a survival strategy via growth acceleration. Remarkably, P. falciparum inhibits CXCL10 synthesis in monocytes by disrupting the association of host ribosomes with CXCL10 transcripts. The underlying inhibition cascade involves RNA cargo delivery into monocytes that triggers RIG-I, which leads to HUR1 binding to an AU-rich domain of the CXCL10 3’UTR. These data indicate that when the parasite can no longer keep CXCL10 at low levels, it can exploit the chemokine as a cue to shift tactics and escape.

scholarly journals Combining QTL Mapping and Gene Expression Analysis to Elucidate the Genetic Control of ‘Crumbly’ Fruit in Red Raspberry (Rubus idaeus L.)

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 794
Author(s):  
Luca M. Scolari ◽  
Robert D. Hancock ◽  
Pete E. Hedley ◽  
Jenny Morris ◽  
Kay Smith ◽  
...  
Keyword(s):  
Genetic Control ◽  
Developmental Disorder ◽  
Molecular Mechanisms ◽  
Developmental Stages ◽  
Microarray Experiment ◽  
Rubus Idaeus ◽  
Red Raspberry ◽  
Genotype By Sequencing ◽  
First Time ◽  
Selection Of

‘Crumbly’ fruit is a developmental disorder in raspberry that results in malformed and unsaleable fruits. For the first time, we define two distinct crumbly phenotypes as part of this work. A consistent crumbly fruit phenotype affecting the majority of fruits every season, which we refer to as crumbly fruit disorder (CFD) and a second phenotype where symptoms vary across seasons as malformed fruit disorder (MFD). Here, segregation of crumbly fruit of the MFD phenotype was examined in a full-sib family and three QTL (Quantitative Trait Loci) were identified on a high density GbS (Genotype by Sequencing) linkage map. This included a new QTL and more accurate location of two previously identified QTLs. A microarray experiment using normal and crumbly fruit at three different developmental stages identified several genes that were differentially expressed between the crumbly and non-crumbly phenotypes within the three QTL. Analysis of gene function highlighted the importance of processes that compromise ovule fertilization as triggers of crumbly fruit. These candidate genes provided insights regarding the molecular mechanisms involved in the genetic control of crumbly fruit in red raspberry. This study will contribute to new breeding strategies and diagnostics through the selection of molecular markers associated with the crumbly trait.

scholarly journals Mitochondrial Processes during Early Development of Dictyostelium discoideum: From Bioenergetic to Proteomic Studies

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 638
Author(s):  
Monika Mazur ◽  
Daria Wojciechowska ◽  
Ewa Sitkiewicz ◽  
Agata Malinowska ◽  
Bianka Świderska ◽  
...  
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Coupling Efficiency ◽  
Slime Mold ◽  
Intact Cells ◽  
Life Cycle Stages ◽  
Early Developmental Stages ◽  
Proteomic Study ◽  
And Function ◽  
Early Developmental

The slime mold Dictyostelium discoideum’s life cycle includes different unicellular and multicellular stages that provide a convenient model for research concerning intracellular and intercellular mechanisms influencing mitochondria’s structure and function. We aim to determine the differences between the mitochondria isolated from the slime mold regarding its early developmental stages induced by starvation, namely the unicellular (U), aggregation (A) and streams (S) stages, at the bioenergetic and proteome levels. We measured the oxygen consumption of intact cells using the Clarke electrode and observed a distinct decrease in mitochondrial coupling capacity for stage S cells and a decrease in mitochondrial coupling efficiency for stage A and S cells. We also found changes in spare respiratory capacity. We performed a wide comparative proteomic study. During the transition from the unicellular stage to the multicellular stage, important proteomic differences occurred in stages A and S relating to the proteins of the main mitochondrial functional groups, showing characteristic tendencies that could be associated with their ongoing adaptation to starvation following cell reprogramming during the switch to gluconeogenesis. We suggest that the main mitochondrial processes are downregulated during the early developmental stages, although this needs to be verified by extending analogous studies to the next slime mold life cycle stages.

The developmental stages of Neobrachiella robusta (Wilson, 1912), a parasitic copepod of Sebastes (Teleostei: Scorpaeniformes)

1987 ◽  
Vol 65 (6) ◽  
pp. 1331-1336
Author(s):  
Z. Kabata
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Parasitic Copepod ◽  
Gill Arch ◽  
Gill Rakers ◽  
Copepodid Stage

The morphology of the developmental stages of Neobrachiella robusta (Wilson, 1912) (Copepoda: Siphonostomatoida) is described. The copepod is parasitic on the gill rakers of Sebastes alutus (Gilbert, 1890) (Teleostei: Scorpaeniformes). The life cycle of this copepod consists of a copepodid stage, followed by four chalimus stages and a relatively long preadult stage, which undergoes extensive metamorphosis. The copepods aggregate on the outer row of long gill rakers of the first gill arch, as many as 97% of them being attached to these rakers. Some of the rakers become distorted, but a connection between the presence of N. robusta and these abnormalities could not be established.

Research of Graphic User Interface of Carbon Dioxide Emission Evaluation Model in Construction Life Cycle Based on Matlab

2013 ◽  
Vol 689 ◽  
pp. 546-550
Author(s):  
Xue Hong Gan ◽  
Wei Wang ◽  
Shi Mei Liu
Keyword(s):  
Carbon Dioxide ◽  
Life Cycle ◽  
Evaluation Model ◽  
Carbon Dioxide Emission ◽  
Graphic User Interface ◽  
Property Management ◽  
Low Carbon ◽  
Management Responsibility ◽  
Residential Quarter ◽  
First Time

To build carbon dioxide emission evaluation model in construction life cycle is the key link to make low-carbon research of theoretical studies head towards practical application. For the first time, residential quarter is selected as the object in the study, carbon dioxide emission management responsibility of owner and property being considered and carbon dioxide emission evaluation model in construction life cycle based on matlab as well as database of carbon dioxide factor being built initially. Net carbon dioxide emission information will be shown timely, then carbon dioxide emission and absorption can be adjusted by property management accordingly.

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