Studies on gametogenesis in Tachygonetria vivipara Wedl, 1862 and Thelandros alatus Wedl, 1862 (Oxyuroidea; Nematoda) from Uromastix acanthinurus in Morocco

1983 ◽  
Vol 61 (10) ◽  
pp. 2357-2360 ◽  
Author(s):  
Martin L. Adamson ◽  
Annie J. Petter
Keyword(s):  
Life Cycle ◽  
Chromosome Pairing ◽  
Diploid Number ◽  
In Utero ◽  
Female Progeny ◽  
New Host ◽  
Transformation Zone ◽  
Bivalent Formation

Chromosome changes during gametogenesis in Thelandros alatus and Tachygonetria vivipara, pharyngodonids (Oxyuroidea; Nematoda) from Uromastix acanthinurus from Morocco, indicate that both species are haplodiploid. Meiosis was normal in females of Thelandros alatus. There were five bivalents, indicating a diploid number of 10 chromosomes. Most embryos in utero contained 5 chromosomes but one was observed with 10. Spermatogonial divisions contained five chromosomes; there was no evidence of chromosome pairing nor bivalent formation in males and divisions in the transformation zone of the testis contained five chromosomes with fuzzy outlines. There was no evidence of chromosome pairing nor bivalent formation in males of Tachygonetria vivipara. Oviparous and ovoviviparous females were examined. Three bivalents formed indicating a diploid number of six chromosomes. Chromosomes were counted in 179 embryos from 79 oviparous females; 128 were diploid (i.e., female) and 51 were haploid (i.e., male). It is suggested that the life cycle of T. vivipara resembles that of Gyrinicola batrachiensis: hosts are colonized by thick-shelled eggs, most of which develop into ovoviviparous females, and these females, if not fecundated, produce males parthenogenetically which develop in the same host. After being fecundated (sometimes by way of mother-son matings) the same females produce oviparous female progeny which develop in the same host. Eggs from oviparous females colonize a new host.

Studies on gametogenesis in Gyrinicola batrachiensis (Walton, 1929) (Oxyuroidea: Nematoda)

1981 ◽  
Vol 59 (7) ◽  
pp. 1368-1376 ◽  
Author(s):  
M. L. Adamson
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Division ◽  
Diploid Number ◽  
Polar Body ◽  
Rana Clamitans ◽  
First Report ◽  
Bivalent Formation ◽  
Normal Meiosis

Cytological aspects of gametogenesis were investigated in populations of Gyrinicola batrachiensis (Oxyuroidea; Nematoda) from various anuran hosts. Populations parasitizing Rana clamitans reproduced by haplodiploidy. Females had eight chromosomes and oocytes underwent normal meiosis. Fertilized eggs containing eight chromosomes and unfertilized eggs containing four chromosomes were observed in the uterus of females. Males had four chromosomes and spermatozoa were produced mitotically. This is the first report of haplodiploidy in a nematode. Populations of G. batrachiensis parasitizing tadpoles in ponds where R. clamitans was absent reproduced by apomictic thelytoky. Females had six, seven, or eight chromosomes depending on the strain. There was no chromosome pairing nor bivalent formation. A diploid number of univalents divided to form a single polar body and a pronucleus. Apomictic strains of G. batrachiensis probably arose when mutations supressed the first meiotic division in haplodiploid strains. Apomictic females do not need to locate a mate and can begin to reproduce as soon as they are mature. Gyrinicola batrachiensis occurs only in the tadpole stage and apomictic strains are most successful in anurans in which the tadpole stage is brief.

Effect of In-Utero Exposure to High Dose Diethylstilbestrol on Intervertebral Disk in Adult Male and Female Progeny

2012 ◽  
Vol 2 (1_suppl) ◽  
pp. s-0032-1319931-s-0032-1319931
Author(s):  
S. Al Rowas ◽  
R. Gawri ◽  
R. Haddad ◽  
A. Almaawi ◽  
L. E. Chalifour ◽  
...  
Keyword(s):  
Adult Male ◽  
In Utero ◽  
Intervertebral Disk ◽  
In Utero Exposure ◽  
High Dose ◽  
Female Progeny ◽  
Male And Female

Autonomy and integration in complex parasite life cycles

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1824-1846 ◽  
Author(s):  
DANIEL P. BENESH
Keyword(s):  
Life Cycle ◽  
Holistic Approach ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Functional Specialization ◽  
Life Stages ◽  
Free Living ◽  
New Host ◽  
Complex Life Cycles ◽  
Life Cycle Stages

SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

CHROMOSOME PAIRING IN POA ANNUA L.

1973 ◽  
Vol 15 (3) ◽  
pp. 549-551 ◽  
Author(s):  
W. M. Ellis ◽  
B. T. O. Lee ◽  
D. M. Calder
Keyword(s):  
Chromosome Pairing ◽  
Breeding System ◽  
Tetraploid Plant ◽  
Poa Annua ◽  
Diploid Population ◽  
Bivalent Formation

Cytological studies carried out on six tetraploid and one diploid population and a synthesized tetraploid plant have shown regular bivalent formation at meiosis. This regularity appears to be genetically controlled in this species. Plants from all the populations behave as diploids. The implications of this regular disomic chromosome pairing on recombination, variation and the breeding system of P. annua are considered.

scholarly journals A Comparison of Stage Conversion in the Coccidian Apicomplexans Toxoplasma gondii, Hammondia hammondi, and Neospora caninum

2020 ◽  
Vol 10 ◽  
Author(s):  
Sarah L. Sokol-Borrelli ◽  
Rachel S. Coombs ◽  
Jon P. Boyle
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Stress Responses ◽  
Neospora Caninum ◽  
Life Forms ◽  
New Host ◽  
Environmental Signals ◽  
Stage Conversion ◽  
Genetic Components ◽  
Species Specific

Stage conversion is a critical life cycle feature for several Apicomplexan parasites as the ability to switch between life forms is critical for replication, dissemination, pathogenesis and ultimately, transmission to a new host. In order for these developmental transitions to occur, the parasite must first sense changes in their environment, such as the presence of stressors or other environmental signals, and then respond to these signals by initiating global alterations in gene expression. As our understanding of the genetic components required for stage conversion continues to broaden, we can better understand the conserved mechanisms for this process and unique components and their contribution to pathogenesis by comparing stage conversion in multiple closely related species. In this review, we will discuss what is currently known about the mechanisms driving stage conversion in Toxoplasma gondii and its closest relatives Hammondia hammondi and Neospora caninum. Work by us and others has shown that these species have some important differences in the way that they (1) progress through their life cycle and (2) respond to stage conversion initiating stressors. To provide a specific example of species-specific complexities associated with stage conversion, we will discuss our recent published and unpublished work comparing stress responses in T. gondii and H. hammondi.

Notes on rust fungi in China 8. Pucciniastrum tiliae life cycle and new host plants inferred from phylogenetic evidence

Mycotaxon ◽  
2020 ◽  
Vol 135 (3) ◽  
pp. 490-499
Author(s):  
Jing-Xin Ji ◽  
Zhuang Li ◽  
Yu Li ◽  
Makoto Kakishima
Keyword(s):  
Life Cycle ◽  
Northeast China ◽  
Host Plants ◽  
Phylogenetic Analyses ◽  
Rust Fungus ◽  
Rust Fungi ◽  
New Host ◽  
First Time

The life cycle connection between spermogonial and aecial stages of a rust fungus found on Abies holophylla and uredinial and telial stages on Tilia mongolica and T. mandshurica collected in northeast China were confirmed by phylogenetic analyses. The rust, identified as Pucciniastrum tiliae, was confirmed by morphological observations. The life cycle of this rust fungus is reported for the first time in China, and A. holophylla and T. mongolica represent new host plants for the species.

Evidence for Sex-specific Effects of TCDD on Male and Female Progeny Exposed in Utero

Epidemiology ◽  
2006 ◽  
Vol 17 (Suppl) ◽  
pp. S93
Author(s):  
B Le Magueress-Battistoni ◽  
F Odet ◽  
C Guigon ◽  
A Vérot ◽  
R Guyot ◽  
...  
Keyword(s):  
In Utero ◽  
Female Progeny ◽  
Male And Female ◽  
Specific Effects

scholarly journals Zoonotic Implications of Onchocerca Species on Human Health

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 761
Author(s):  
Maria Cambra-Pellejà ◽  
Javier Gandasegui ◽  
Rafael Balaña-Fouce ◽  
José Muñoz ◽  
María Martínez-Valladares
Keyword(s):  
Life Cycle ◽  
Human Health ◽  
One Health ◽  
Parasitic Disease ◽  
New Host ◽  
Ocular Tissues ◽  
Subcutaneous Nodules ◽  
Wide Geographical Distribution ◽  
And Control ◽  
Prepatency Period

The genus Onchocerca includes several species associated with ungulates as hosts, although some have been identified in canids, felids, and humans. Onchocerca species have a wide geographical distribution, and the disease they produce, onchocerciasis, is generally seen in adult individuals because of its large prepatency period. In recent years, Onchocerca species infecting animals have been found as subcutaneous nodules or invading the ocular tissues of humans; the species involved are O. lupi, O. dewittei japonica, O. jakutensis, O. gutturosa, and O. cervicalis. These findings generally involve immature adult female worms, with no evidence of being fertile. However, a few cases with fertile O. lupi, O. dewittei japonica, and O. jakutensis worms have been identified recently in humans. These are relevant because they indicate that the parasite’s life cycle was completed in the new host—humans. In this work, we discuss the establishment of zoonotic Onchocerca infections in humans, and the possibility of these infections to produce symptoms similar to human onchocerciasis, such as dermatitis, ocular damage, and epilepsy. Zoonotic onchocerciasis is thought to be an emerging human parasitic disease, with the need to take measures such as One Health Strategies, in order to identify and control new cases in humans.

Planktonic Distribution of Sea Lice Larvae, Lepeophtheirus Salmonis, in Killary Harbour, West Coast of Ireland

1998 ◽  
Vol 78 (3) ◽  
pp. 853-874 ◽  
Author(s):  
M. Costelloe ◽  
J. Costelloe ◽  
G. O'Donohoe ◽  
N.J. Coghlan ◽  
M. Oonk ◽  
...  
Keyword(s):  
Life Cycle ◽  
Water Temperature ◽  
West Coast ◽  
Distribution Density ◽  
Sea Lice ◽  
Lepeophtheirus Salmonis ◽  
Summer Period ◽  
New Host ◽  
Resident Fish ◽  
Subsequent Decrease

The distribution of Lepeophtheirus salmonis larvae in Killary Harbour was investigated by taking plankton tows from a number of stations on a regular basis during the spring/summer period in 1995 and 1996. Current patterns, ovigerous lice loads on the resident fish and water temperature and salinity were also recorded during the study. Larvae were only found consistently at a station close to a salmon farm at the mouth of the harbour. In the inner harbour, close to the mouths of two rivers, larvae were recovered in sporadic time blocks. Highest densities of larvae were found at the beginning of the study in both years in the inner harbour with a subsequent decrease in the following months. The distribution, density and origin of the larvae are discussed in relation to the prevailing current patterns in the harbour, the ovigerous lice loads on the resident fish and the requirements of the larvae to locate a new host and complete the life cycle.

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