scholarly journals The Tissue Tropisms and Transstadial Transmission of a Rickettsia Endosymbiont in the Highland Midge, Culicoides impunctatus (Diptera: Ceratopogonidae)

2020 ◽  
Author(s):  
Jack Pilgrim ◽  
Stefanos Siozios ◽  
Matthew Baylis ◽  
Gregory D. D. Hurst
Keyword(s):  
Vertical Transmission ◽  
Developmental Stages ◽  
Fat Body ◽  
Horizontal Transmission ◽  
Follicle Cells ◽  
Biting Midges ◽  
Diverse Range ◽  
Suspensory Ligament ◽  
Transstadial Transmission ◽  
Tissue Tropisms

AbstractRickettsia are a group of intracellular bacteria which can manipulate host reproduction and alter sensitivity to natural enemy attack in a diverse range of arthropods. The maintenance of Rickettsia endosymbionts in insect populations can be achieved through both vertical and horizontal transmission routes. For example, the presence of the symbiont in the follicle cells and salivary glands of Bemisia whiteflies allows Belli group Rickettsia transmission via the germline and plants, respectively. However, the transmission routes of other Rickettsia, such as those in the Torix group of the genus, remain underexplored. Through fluorescence in-situ hybridisation (FISH) and transmission electron microscopy (TEM) screening, this study describes the pattern of Torix Rickettsia tissue tropisms in the highland midge, Culicoides impunctatus (Diptera: Ceratopogonidae). Of note is high intensity of infection of the ovarian suspensory ligament, suggestive of a novel germline targeting strategy. Additionally, localisation of the symbiont in tissues of several developmental stages suggests transstadial transmission is a major route of ensuring maintenance of Rickettsia within C. impunctatus populations. Aside from providing insights into transmission strategies, Rickettsia presence in the fat body of larvae indicates potential host fitness and vector capacity impacts to be investigated in the future.Importance StatementMicrobial symbionts of disease vectors have garnered recent attention due to their ability to alter vectorial capacity. Their consideration as a means of arbovirus control depends on symbiont vertical transmission which leads to spread of the bacteria through a population. Previous work has identified a Rickettsia symbiont present in several vector species of biting midges (Culicoides spp.), however, symbiont transmission strategies and host effects remain underexplored. In this study, we describe the presence of Rickettsia in the ovarian suspensory ligament and the ovarian epithelial sheath of Culicoides impunctatus. Infection of these organs suggest the connective tissue surrounding developing eggs is important for ensuring vertical transmission of the symbiont in midges and possibly other insects. Additionally, our results indicate Rickettsia localisation in the fat body of Culicoides impunctatus. As viruses spread by midges often replicate in the fat body, this implies possible vector competence effects to be further investigated.

scholarly journals Tissue Tropisms and Transstadial Transmission of a Rickettsia Endosymbiont in the Highland Midge, Culicoides impunctatus (Diptera: Ceratopogonidae)

2020 ◽  
Vol 86 (20) ◽  
Author(s):  
Jack Pilgrim ◽  
Stefanos Siozios ◽  
Matthew Baylis ◽  
Gregory D. D. Hurst
Keyword(s):  
Vertical Transmission ◽  
Fat Body ◽  
Germ Line ◽  
Horizontal Transmission ◽  
Follicle Cells ◽  
Biting Midges ◽  
Diverse Range ◽  
Suspensory Ligament ◽  
Transstadial Transmission ◽  
Tissue Tropisms

ABSTRACT Rickettsia is a genus of intracellular bacteria which can manipulate host reproduction and alter sensitivity to natural enemy attack in a diverse range of arthropods. The maintenance of Rickettsia endosymbionts in insect populations can be achieved through both vertical and horizontal transmission routes. For example, the presence of the symbiont in the follicle cells and salivary glands of Bemisia whiteflies allows Belli group Rickettsia transmission via the germ line and plants, respectively. However, the transmission routes of other Rickettsia bacteria, such as those in the Torix group of the genus, remain underexplored. Through fluorescence in situ hybridization (FISH) and transmission electron microscopy (TEM) screening, this study describes the pattern of Torix Rickettsia tissue tropisms in the highland midge, Culicoides impunctatus (Diptera: Ceratopogonidae). Of note is the high intensity of infection of the ovarian suspensory ligament, suggestive of a novel germ line targeting strategy. Additionally, localization of the symbiont in tissues of several developmental stages suggests transstadial transmission is a major route for ensuring maintenance of Rickettsia within C. impunctatus populations. Aside from providing insights into transmission strategies, the presence of Rickettsia bacteria in the fat body of larvae indicates potential host fitness and vector capacity impacts to be investigated in the future. IMPORTANCE Microbial symbionts of disease vectors have garnered recent attention due to their ability to alter vectorial capacity. Their consideration as a means of arbovirus control depends on symbiont vertical transmission, which leads to spread of the bacteria through a population. Previous work has identified a Rickettsia symbiont present in several species of biting midges (Culicoides spp.), which transmit bluetongue and Schmallenberg arboviruses. However, symbiont transmission strategies and host effects remain underexplored. In this study, we describe the presence of Rickettsia in the ovarian suspensory ligament of Culicoides impunctatus. Infection of this organ suggests the connective tissue surrounding developing eggs is important for ensuring vertical transmission of the symbiont in midges and possibly other insects. Additionally, our results indicate Rickettsia localization in the fat body of Culicoides impunctatus. As the arboviruses spread by midges often replicate in the fat body, this location implies possible symbiont-virus interactions to be further investigated.

scholarly journals Vertical Transmission of a Drosophila Endosymbiont Via Cooption of the Yolk Transport and Internalization Machinery

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Jeremy K. Herren ◽  
Juan C. Paredes ◽  
Fanny Schüpfer ◽  
Bruno Lemaitre
Keyword(s):  
Vertical Transmission ◽  
Fat Body ◽  
Germ Line ◽  
Ovarian Follicle ◽  
Follicle Cells ◽  
Content Type ◽  
Vector Borne Diseases ◽  
Severe Reduction ◽  
Female Germ Line ◽  
Vector Borne

ABSTRACTSpiroplasmais a diverse bacterial clade that includes many vertically transmitted insect endosymbionts, includingSpiroplasma poulsonii, a natural endosymbiont ofDrosophila melanogaster. These bacteria persist in the hemolymph of their adult host and exhibit efficient vertical transmission from mother to offspring. In this study, we analyzed the mechanism that underlies their vertical transmission, and here we provide strong evidence that these bacteria use the yolk uptake machinery to colonize the germ line. We show thatSpiroplasmareaches the oocyte by passing through the intercellular space surrounding the ovarian follicle cells and is then endocytosed into oocytes within yolk granules during the vitellogenic stages of oogenesis. Mutations that disrupt yolk uptake by oocytes inhibit verticalSpiroplasmatransmission and lead to an accumulation of these bacteria outside the oocyte. Impairment of yolk secretion by the fat body results inSpiroplasmanot reaching the oocyte and a severe reduction of vertical transmission. We propose a model in whichSpiroplasmafirst interacts with yolk in the hemolymph to gain access to the oocyte and then uses the yolk receptor, Yolkless, to be endocytosed into the oocyte. Cooption of the yolk uptake machinery is a powerful strategy for endosymbionts to target the germ line and achieve vertical transmission. This mechanism may apply to other endosymbionts and provides a possible explanation for endosymbiont host specificity.IMPORTANCEMost insect species, including important disease vectors and crop pests, harbor vertically transmitted endosymbiotic bacteria. Studies have shown that many facultative endosymbionts, includingSpiroplasma, confer protection against different classes of parasites on their hosts and therefore are attractive tools for the control of vector-borne diseases. The ability to be efficiently transmitted from females to their offspring is the key feature shaping associations between insects and their inherited endosymbionts, but to date, little is known about the mechanisms involved. In oviparous animals, yolk accumulates in developing eggs and serves to meet the nutritional demands of embryonic development. Here we show thatSpiroplasma coopts the yolk transport and uptake machinery to colonize the germ line and ensure efficient vertical transmission. The uptake of yolk is a female germ line-specific feature and therefore an attractive target for cooption by endosymbionts that need to maintain high-fidelity maternal transmission.

Two actions of juvenile hormone on the follicle cells of Rhodnius prolixus Stål

1975 ◽  
Vol 53 (8) ◽  
pp. 1187-1188 ◽  
Author(s):  
Randa Abu-Hakima ◽  
K. G. Davey
Keyword(s):  
Juvenile Hormone ◽  
Developmental Stages ◽  
Normal Animal ◽  
Rhodnius Prolixus ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Intercellular Spaces

The follicular epithelium of vitellogenic oocytes from allatectomized females of Rhodnius fails to develop large intercellular spaces when exposed to juvenile hormone (JH) in vitro. This suggests that in the normal animal, the follicle cells require JH at two developmental stages. Differentiation of the cells in the presence of JH represents one requirement, and only those cells which have undergone this initial priming are fully competent to exhibit the second response, the development of intercellular spaces.

Oogenesis in Lucilia Cuprina (Wied.) (Diptera: Calliphoridae). Ii. The Effect of Aziridinyl Chemosterilants on Oogenesis.

1979 ◽  
Vol 27 (3) ◽  
pp. 349 ◽  
Author(s):  
GAC Beattie
Keyword(s):  
Direct Effect ◽  
Nurse Cell ◽  
Ovarian Development ◽  
Fat Body ◽  
Endocrine System ◽  
Lucilia Cuprina ◽  
Follicle Cells ◽  
Cell Nuclei

Inhibition of ovarian development in L. cuprina by two aziridinyl chemosterilants, N,N'-hexamethylenebis(1-aziridinecarboxamide) and N. N'bisaziridinyl-N"-cyclohexylphosphine sulphide, was due to the direct effect of the sterilants on the ovary. The sterilants caused infecundity by interfering with mitosis in the follicle cells. Contrary to the accepted view, no evidence was obtained to suggest that infecundity resulted from inhibition of endomitosis in the nurse cell nuclei. Neither sterilant prevented the digestion of protein by the midgut, nor did they prevent the endocrine system and fat body from functioning.

scholarly journals Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis

2020 ◽  
Vol 125 (6) ◽  
pp. 981-991 ◽  
Author(s):  
Pedro E Gundel ◽  
Prudence Sun ◽  
Nikki D Charlton ◽  
Carolyn A Young ◽  
Tom E X Miller ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Transmission Rate ◽  
Horizontal Transmission ◽  
Fungal Endophytes ◽  
Natural Populations ◽  
Plant Tolerance ◽  
Hyphal Density ◽  
Symbiotic Fungi ◽  
Symbiont Transmission ◽  
Fitness Benefits

Abstract Background and Aims The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloë spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission? Methods We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloë. We measured plant fitness (survival, growth, reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission. Key Results Poa autumnalis hosted two Epichloë taxa, an undescribed vertically transmitted Epichloë sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivory increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission. Conclusions Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations.

scholarly journals Evolution of early male-killing in horizontally transmitted parasites

2015 ◽  
Vol 282 (1818) ◽  
pp. 20152068 ◽  
Author(s):  
Veronika Bernhauerová ◽  
Luděk Berec ◽  
Daniel Maxin
Keyword(s):  
Empirical Evidence ◽  
Vertical Transmission ◽  
Bacterial Strain ◽  
Horizontal Transmission ◽  
Distinct Species ◽  
High Efficacy ◽  
Infected Male ◽  
Male Killing ◽  
Wide Range ◽  
Male Killer

Early male-killing (MK) bacteria are vertically transmitted reproductive parasites which kill male offspring that inherit them. Whereas their incidence is well documented, characteristics allowing originally non-MK bacteria to gradually evolve MK ability remain unclear. We show that horizontal transmission is a mechanism enabling vertically transmitted bacteria to evolve fully efficient MK under a wide range of host and parasite characteristics, especially when the efficacy of vertical transmission is high. We also show that an almost 100% vertically transmitted and 100% effective male-killer may evolve from a purely horizontally transmitted non-MK ancestor, and that a 100% efficient male-killer can form a stable coexistence only with a non-MK bacterial strain. Our findings are in line with the empirical evidence on current MK bacteria, explain their high efficacy in killing infected male embryos and their variability within and across insect taxa, and suggest that they may have evolved independently in phylogenetically distinct species.

scholarly journals Theca: the forgotten cell of the ovarian follicle

Reproduction ◽  
2010 ◽  
Vol 140 (4) ◽  
pp. 489-504 ◽  
Author(s):  
J M Young ◽  
A S McNeilly
Keyword(s):  
Granulosa Cells ◽  
Developmental Stages ◽  
Vascular System ◽  
Ovarian Follicle ◽  
Primary Follicle ◽  
Diverse Range ◽  
Theca Cells ◽  
Structural Support ◽  
Highly Active ◽  
Thecal Cells

Theca cells function in a diverse range of necessary roles during folliculogenesis; to synthesize androgens, provide crosstalk with granulosa cells and oocytes during development, and provide structural support of the growing follicle as it progresses through the developmental stages to produce a mature and fertilizable oocyte. Thecal cells are thought to be recruited from surrounding stromal tissue by factors secreted from an activated primary follicle. The precise origin and identity of these recruiting factors are currently not clear, but it appears that thecal recruitment and/or differentiation involves not just one signal, but a complex and tightly controlled combination of multiple factors. It is clear that thecal cells are fundamental for follicular growth, providing all the androgens required by the developing follicle(s) for conversion into estrogens by the granulosa cells. Their function is enabled through the establishment of a vascular system providing communication with the pituitary axis throughout the reproductive cycle, and delivering essential nutrients to these highly active cells. During development, the majority of follicles undergo atresia, and the theca cells are often the final follicular cell type to die. For those follicles that do ovulate, the theca cells then undergo hormone-dependent differentiation into luteinized thecal cells of the corpus luteum. While the theca is an essential component of follicle development and ovulation, we do not yet fully understand the control of recruitment and function of theca cells, an important consideration since their function appears to be altered in certain causes of infertility.

scholarly journals Application of the Neospora Caninum IgG Avidity ELISA in Assessment of Chronic Reproductive Losses after an Outbreak of Neosporosis in a Herd of Beef Cattle

2003 ◽  
Vol 15 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Camilla Björkman ◽  
Milton M. McAllister ◽  
Jenny Frössling ◽  
Katarina Näslund ◽  
Felicia Leung ◽  
...  
Keyword(s):  
Point Source ◽  
Pregnancy Rate ◽  
Vertical Transmission ◽  
Neospora Caninum ◽  
Horizontal Transmission ◽  
Beef Cows ◽  
Abortion Rate ◽  
Reproductive Effects ◽  
Igg Avidity ◽  
Beef Herd

Point-source infections are most likely the cause for Neospora caninum–induced abortion outbreaks in cattle, whereas an increased annual abortion rate may be a consequence of vertical transmission. The aims of the present study were to examine the reproductive effects of neosporosis in a beef herd for 3 years, after a point-source outbreak and to use IgG avidity serology to examine the chronicity of infections and patterns of transmission. During the study, 76–78% of animals were seropositive for N. caninum. The pregnancy rate varied from 88% to 94%, without any reduction in the pregnancy rate of seropositive cows compared with seronegative cows. The annual abortion rate was 2.5–5.5%, and all but 1 abortion occurred in seropositive dams. The efficiency of vertical transmission was estimated to be 85%. Several calves, born to seronegative dams, were seropositive at 6–13 months of age, indicating a 22% mean annual rate of horizontal transmission. The mean avidity in seropositive cows increased from 30 during the initial outbreak to 74 after 3 years. The mode of IgG avidity was 21–40 during the initial abortion outbreak, 41–60 after 1 year, and 61–80 after 2 and 3 years. The results reveal high annual rates of both vertical and horizontal transmission of N. caninum in a herd of beef cows and provide further validation on the ability of the N. caninum IgG avidity ELISA to accurately assess the chronicity of infection.

Ovarian morphology and oogenesis of Leptodesmus dentellus (Diplopoda, Polydesmida, Chelodesmidae)

2013 ◽  
Vol 63 (2) ◽  
pp. 169-184
Author(s):  
Márcia C. Zirondi ◽  
Tamaris G. Pinheiro ◽  
Carmem S. Fontanetti
Keyword(s):  
Developmental Stages ◽  
Fat Body ◽  
Reproductive Organ ◽  
The Body ◽  
Anterior Region ◽  
Follicular Epithelium ◽  
Ovarian Morphology ◽  
Juvenile Stages ◽  
Double Origin

This study presents the ovarian morphology and the dynamics of the vitellogenesis process in the oocytes of the diplopod Leptodesmus dentellus. The oocytes are arranged in clusters called ovisacs which are distributed in pairs along the midline of the body forming the ovary. Regions similar to the germarium appear paired in the anterior region of the ovary; however, the development of the oocytes of this species does not follow a regionalisation in the reproductive organ. Cells in three developmental stages are found throughout the length of the ovary. Calcium, proteins, lipids and neutral polysaccharides were detected in the oocytes of L. dentellus. The polysaccharides and the proteins found in the oocytes have a double origin: endogenous, with the participation of the germinative vesicle, and exogenous, from follicular epithelium. The origin of the lipids is exogenous, i.e., they are incorporated into the oocytes, probably derived from the perivisceral fat body, which are highly developed in this region. The deposition of calcium is pre-vitellogenic and probably functions as a reserve during the juvenile stages.

scholarly journals Viral hepatitis B and C in HIV-exposed South African infants

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Cynthia Tamandjou Tchuem ◽  
Mark Fredric Cotton ◽  
Etienne Nel ◽  
Richard Tedder ◽  
Wolfgang Preiser ◽  
...  
Keyword(s):  
South Africa ◽  
Hepatitis B ◽  
Vertical Transmission ◽  
Horizontal Transmission ◽  
Hbv Dna ◽  
Molecular Testing ◽  
Lamivudine Resistance ◽  
Hiv Exposed Infants ◽  
Hcv Antibody ◽  
Hiv Exposed

Abstract Background Whilst much attention is given to eliminating HIV mother-to-child transmission (MTCT), little has been done to ensure the same for hepatitis B virus (HBV) transmission. The introduction of HBV immunization at six weeks of age has reduced HBV horizontal transmission in South Africa. However, in order to eliminate HBV MTCT, further interventions are needed. The risk of hepatitis C virus (HCV) MTCT in HIV-infected (HIV+) African women is not yet well described. This study aimed to determine the rate of HBV and HCV vertical transmission in HIV-exposed infants in South Africa. Methods Serum samples from infants enrolled in an isoniazid prevention study (P1041) were screened for HBV and HCV serology markers; screening was performed on samples collected at approximately 60 weeks of age of the infants. HBV DNA was quantified in HBsAg positive samples and HBV strains characterized through gene sequencing. All HCV antibody samples with inconclusive results underwent molecular testing. Results Three of 821 infants were positive for both HBsAg and HBV DNA. All HBV strains belonged to HBV sub-genotype A1. The rtM204I mutation associated with lamivudine resistance was identified in one infant, a second infant harboured the double A1762T/G1764A BCP mutation. Phylogenetic analysis showed clustering between mother and infant viral genomic sequences. Twenty-one of 821 HIV-exposed infants tested had inconclusive HCV antibody results, none were HCV PCR positive. Conclusions This study suggests that HBV vertical transmission is likely to be occurring in HIV-exposed infants in South Africa.. A more robust strategy of HBV prevention, including birth dose vaccination, is required to eradicate HBV MTCT. HCV infection was not detected.

Sign in / Sign up

Export Citation Format

Share Document