Gametocyte sex ratio of a malaria parasite: response to experimental manipulation of parasite clonal diversity

Parasitology ◽  
2004 ◽  
Vol 128 (1) ◽  
pp. 23-29 ◽  
Author(s):  
S. M. OSGOOD ◽  
J. J. SCHALL
Keyword(s):  
Sex Ratio ◽  
Malaria Parasite ◽  
Clonal Diversity ◽  
Experimental Manipulation ◽  
Sceloporus Occidentalis ◽  
Infected Blood ◽  
Single Donor ◽  
Mixed Blood ◽  
Sex Ratio Theory ◽  
Male To Female

Sex ratio theory posits that the adaptive proportion of male to female gametocytes of a malaria parasite within the vertebrate host depends on the degree of inbreeding within the vector. Gametocyte sex ratio could be phenotypically flexible, being altered based on the infection's clonal diversity, and thus likely inbreeding. This idea was tested by manipulating the clonal diversity of infections of Plasmodium mexicanum in its lizard host, Sceloporus occidentalis. Naive lizards were inoculated with infected blood from a single donor or 3 pooled donors. Donors varied in their gametocyte sex ratios (17–46% male), and sex ratio theory allowed estimation of the clonal diversity within donor and recipient infections. Phenotypic plasticity would produce a correlation between donor and recipient infections for infections initiated from a single donor, and a less female-biased gametocyte sex ratio in recipients that received a mixed blood inoculum (with predicted higher clonal diversity) than recipients receiving blood from a single donor. Neither pattern was observed. Gametocyte sex ratio of most infections ranged from 35 to 42% male, expected if clonal diversity was high for all infections. Alternative explanations are suggested for the observed variation of gametocyte sex ratio among P. mexicanum infections.

Male gametocyte fecundity and sex ratio of a malaria parasite, Plasmodium mexicanum

Parasitology ◽  
2011 ◽  
Vol 138 (10) ◽  
pp. 1203-1210 ◽  
Author(s):  
A. T. NEAL
Keyword(s):  
Genetic Variation ◽  
Sex Ratio ◽  
Evolutionary Theory ◽  
Malaria Parasite ◽  
Clonal Diversity ◽  
Male Gametes ◽  
A Value ◽  
Parasite Plasmodium ◽  
Sex Ratio Theory ◽  
Few Data

SUMMARYEvolutionary theory predicts that the sex ratio of Plasmodium gametocytes will be determined by the number of gametes produced per male gametocyte (male fecundity), parasite clonal diversity and any factor that reduces male gametes' ability to find and combine with female gametes. Despite the importance of male gametocyte fecundity for sex ratio theory as applied to malaria parasites, few data are available on gamete production by male gametocytes. In this study, exflagellating gametes, a measure of male fecundity, were counted for 866 gametocytes from 26 natural infections of the lizard malaria parasite, Plasmodium mexicanum. The maximum male fecundity observed was 8, but most gametocytes produced 2–3 gametes, a value consistent with the typical sex ratio observed for P. mexicanum. Male gametocytes in infections with higher gametocytaemia had lower fecundity. Male fecundity was not correlated with gametocyte size, but differed among infections, suggesting genetic variation for fecundity. Fecundity and sex ratio were correlated (more female gametocytes with higher fecundity) as predicted by theory. Results agree with evolutionary theory, but also suggest a possible tradeoff between production time and fecundity, which could explain the low fecundity of this species, the variation among infections, and the correlation with gametocytaemia.

Clonal diversity within infections and the virulence of a malaria parasite,Plasmodium mexicanum

Parasitology ◽  
2008 ◽  
Vol 135 (12) ◽  
pp. 1363-1372 ◽  
Author(s):  
A. M. Vardo-ZALIK ◽  
J. J. Schall
Keyword(s):  
Malaria Parasite ◽  
Blood Clotting ◽  
Haemoglobin Concentration ◽  
Clonal Diversity ◽  
Sceloporus Occidentalis ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Parasite Plasmodium ◽  
Blood Haemoglobin ◽  
The Cost

SUMMARYBoth verbal and mathematical models of parasite virulence predict that genetic diversity of microparasite infections will influence the level of costs suffered by the host. We tested this idea by manipulating the number of co-existing clones ofPlasmodium mexicanumin its natural vertebrate host, the fence lizardSceloporus occidentalis. We established replicate infections ofP.mexicanummade up of 1, 2, 3, or >3 clones (scored using 3 microsatellite loci) to observe the influence of clone number on several measures of parasite virulence. Clonal diversity did not affect body growth or production of immature erythrocytes. Blood haemoglobin concentration was highest for the most genetically complex infections (equal to that of non-infected lizards), and blood glucose levels and rate of blood clotting was highest for the most diverse infections (with greater glucose and more rapid clotting than non-infected animals). Neither specific clones nor parasitaemia were associated with virulence. In this first experiment that manipulated the clonal diversity of a naturalPlasmodium-host system, the cost of infection with 1 or 2 clones ofP.mexicanumwas similar to that previously reported for infected lizards, but the most complex infections had either no cost or could be beneficial for the host.

Gametocyte sex ratio in single-clone infections of the malaria parasite Plasmodium mexicanum

Parasitology ◽  
2010 ◽  
Vol 137 (13) ◽  
pp. 1851-1859 ◽  
Author(s):  
A.T. NEAL ◽  
J.J. SCHALL
Keyword(s):  
Genetic Variation ◽  
Sex Ratio ◽  
Malaria Parasite ◽  
Sex Ratios ◽  
Experimental Studies ◽  
Life History Trait ◽  
Gametocyte Density ◽  
Male Gametes ◽  
Single Clone ◽  
Sex Ratio Theory

SUMMARYSex ratio theory predicts that malaria parasites should bias gametocyte production toward female cells in single-clone infections because they will experience complete inbreeding of parasite gametes within the vector. A higher proportion of male gametocytes is favoured under conditions that reduce success of male gametes at reaching females such as low gametocyte density or attack of the immune system later in the infection. Recent experimental studies reveal genetic variation for gametocyte sex ratio in single-clone infections. We examined these issues with a study of experimental single-clone infections for the lizard malaria parasite Plasmodium mexicanum in its natural host. Gametocyte sex ratios of replicate single-clone infections were determined over a period of 3–4 months. Sex ratios were generally female biased, but not as strongly as expected under simple sex ratio theory. Gametocyte density was not related to sex ratio, and male gametocytes did not become more common later in infections. The apparent surplus of male gametocytes could be explained if male fecundity is low in this parasite, or if rapid clotting of the lizard blood reduces male gamete mobility. There was also a significant clone effect on sex ratio, suggesting genetic variation for some life-history trait, possibly male fecundity.

scholarly journals Sex ratios in the rodent malaria parasite, Plasmodium chabaudi

Parasitology ◽  
2003 ◽  
Vol 127 (5) ◽  
pp. 419-425 ◽  
Author(s):  
S. E. REECE ◽  
A. B. DUNCAN ◽  
S. A. WEST ◽  
A. F. READ
Keyword(s):  
Mortality Rate ◽  
Sex Ratio ◽  
Malaria Parasite ◽  
Sex Ratios ◽  
Plasmodium Chabaudi ◽  
Rodent Malaria Parasite ◽  
Malaria Parasites ◽  
Rodent Malaria ◽  
Sex Ratio Theory

The sex ratios of malaria and related Apicomplexan parasites play a major role in transmission success. Here, we address 2 fundamental issues in the sex ratios of the rodent malaria parasite, Plasmodium chabaudi. First we test the accuracy of empirical methods for estimating sex ratios in malaria parasites, and show that sex ratios made with standard thin smears may overestimate the proportion of female gametocytes. Secondly, we test whether the mortality rate differs between male and female gametocytes, as assumed by sex ratio theory. Conventional application of sex ratio theory to malaria parasites assumes that the primary sex ratio can be accurately determined from mature gametocytes circulating in the peripheral circulation. We stopped gametocyte production with chloroquine in order to study a cohort of gametocytes in vitro. The mortality rate was significantly higher for female gametocytes, with an average half-life of 8 h for female gametocytes and 16 h for male gametocytes.

scholarly journals Sex-specific deaths in Norway and Sweden during the COVID-19 pandemic: Did mandates make a difference?

2021 ◽  
pp. 140349482110100
Author(s):  
Ralph Catalano
Keyword(s):  
Sex Ratio ◽  
Infection Control ◽  
Temporal Variation ◽  
Risky Behavior ◽  
Control Strategies ◽  
Sex Ratios ◽  
Female Mortality ◽  
All Cause Mortality ◽  
Societal Expectations ◽  
Male To Female

Aims: To determine whether differences between Norway’s and Sweden’s attempts to contain SARS-CoV-2 infection coincided with detectably different changes in their all-cause mortality sex ratios. Measuring temporal variation in the all-cause mortality sex ratio before and during the pandemic in populations exposed to different constraints on risky behavior would allow us to better anticipate changes in the ratio and to better understand its association with infection control strategies. Methods: I apply time Box–Jenkins modeling to 262 months of pre-pandemic mortality sex ratios to arrive at counterfactual values of 10 intra-pandemic ratios. I compare counterfactual to observed values to determine if intra-pandemic ratios differed detectably from those expected as well as whether the Norwegian and Swedish differences varied from each other. Results: The male to female mortality sex ratio in both Norway and Sweden increased during the pandemic. I, however, find no evidence that the increase differed between the two countries despite their different COVID-19 containment strategies. Conclusion: Societal expectations of who will die during the COVID-19 pandemic will likely be wrong if they assume pre-pandemic mortality sex ratios because the intra-pandemic ratios appear, at least in Norway and Sweden, detectably higher. The contribution of differences in policies to reduce risky behavior to those higher ratios appears, however, small.

scholarly journals Molecular characterization and distribution of Plasmodium matutinum, a common avian malaria parasite

Parasitology ◽  
2017 ◽  
Vol 144 (13) ◽  
pp. 1726-1735 ◽  
Author(s):  
GEDIMINAS VALKIŪNAS ◽  
MIKAS ILGŪNAS ◽  
DOVILĖ BUKAUSKAITĖ ◽  
VAIDAS PALINAUSKAS ◽  
RASA BERNOTIENĖ ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Molecular Characterization ◽  
Malaria Parasite ◽  
Avian Malaria ◽  
Clinical Signs ◽  
Molecular Data ◽  
Infected Blood ◽  
Avian Malaria Parasite ◽  
Thrush Nightingale

SUMMARYSpecies of Plasmodium (Plasmodiidae, Haemosporida) are widespread and cause malaria, which can be severe in avian hosts. Molecular markers are essential to detect and identify parasites, but still absent for many avian malaria and related haemosporidian species. Here, we provide first molecular characterization of Plasmodium matutinum, a common agent of avian malaria. This parasite was isolated from a naturally infected thrush nightingale Luscinia luscinia (Muscicapidae). Fragments of mitochondrial, apicoplast and nuclear genomes were obtained. Domestic canaries Serinus canaria were susceptible after inoculation of infected blood, and the long-lasting light parasitemia developed in two exposed birds. Clinical signs of illness were not reported. Illustrations of blood stages of P. matutinum (pLINN1) are given, and phylogenetic analysis identified the closely related avian Plasmodium species. The phylogeny based on partial cytochrome b (cyt b) sequences suggests that this parasite is most closely related to Plasmodium tejerai (cyt b lineage pSPMAG01), a common malaria parasite of American birds. Both these parasites belong to subgenus Haemamoeba, and their blood stages are similar morphologically, particularly due to marked vacuolization of the cytoplasm in growing erythrocytic meronts. Molecular data show that transmission of P. matutinum (pLINN1) occurs broadly in the Holarctic, and the parasite likely is of cosmopolitan distribution. Passeriform birds and Culex mosquitoes are common hosts. This study provides first molecular markers for detection of P. matutinum.

scholarly journals The Effect of China’s Two-Child Policy on the Child Sex Ratio: Evidence From Shanghai, China

2022 ◽  
Vol 59 ◽  
pp. 004695802110679
Author(s):  
Di Tang ◽  
Xiangdong Gao ◽  
Jiaoli Cai ◽  
Peter. C. Coyte
Keyword(s):  
Sex Ratio ◽  
Sex Ratio At Birth ◽  
Difference In Differences ◽  
Female Sex ◽  
One Child Policy ◽  
Child Policy ◽  
Pregnancy Status ◽  
The One ◽  
Male To Female ◽  
Municipal Level

Objective: The bias towards males at birth has resulted in a major imbalance in the Chinese sex ratio that is often attributed to China’s one-child policy. Relaxation of the one-child policy has the potential to reduce the imbalance in the sex ratio away from males. In this study, we assessed whether the bias towards males in the child sex ratio was reduced as a result of the two-child policy in China. Medical records data from one large municipal-level obstetrics hospital in Shanghai, East China. Design: Matching and difference-in-differences (MDID) techniques were used to investigate the effect of the two-child policy on the imbalance in the sex ratio at birth after matching for pregnancy status and socioeconomic factors. Results: Analyzing 133,358 live births suggest that the relaxation of the one-child policy had a small, but statistically significant effect in reducing the imbalance in the male to female sex ratio at birth. Conclusion: The results demonstrate that relaxation of the one-child policy reduced the imbalance in the male to female sex ratio at birth from 1.10 to 1.05 over the study period at one of the major obstetrics and gynecology hospitals in China.

scholarly journals Ascitic Fluid Cytology Seen in a Tertiary Hospital in Nigeria

2020 ◽  
pp. 345-350
Author(s):  
CC Nwafor ◽  
K Obioha ◽  
TO Akhiwu
Keyword(s):  
Sex Ratio ◽  
Patient Care ◽  
Ascitic Fluid ◽  
Age Groups ◽  
Tertiary Hospital ◽  
Age Group ◽  
Malignant Cells ◽  
Female Ratio ◽  
Male To Female ◽  
Fluid Cytology

Ascites is a symptom that can originate due to diverse pathologies. A lot of investigations including ascitic fluid cytology (AFC) can be done on it to help determine its origin. The aim of this study, is to document the findings and highlight the importance of AFC in patient care in Uyo. All AFC reports and slides in the Department of Histopathology, University of Uyo were retrieved, reviewed and used for this study. The age ranged from 1.5 – 80 years with mean age, 41.79 (±17.23) years. About 71.8% of the ascitic fluid (AF) specimens were from patients between the 3rd and 6th decade. Females predominated in all age groups expect 10-19 year's group, with a male to female sex ratio of 1:2.4. Malignant cells were seen in 28.7% of all the samples, while 51.2% were negative for malignant cells. Malignant cells were seen in 4 (6.7%), 11 (18.3%) and 6 (10%) of the AFC performed due to various liver pathologies, ovarian malignancies and intra-abdominal malignancies respectively. Malignant cells were found more in females with a male to female ratio of 1: 3.6. Age group 40-49 years accounted for most of the malignant cases (26.6%). The pattern of AFC in Uyo is similar to the pattern in other parts of Nigeria

Sign in / Sign up

Export Citation Format

Share Document