Fasciola hepatica: the infection rate and the development of redial generations in Lymnaea truncatula exposed to miracidia after experimental desiccation and activation in water

1994 ◽  
Vol 68 (1) ◽  
pp. 63-66 ◽  
Author(s):  
D. Rondelaud
Keyword(s):  
Infection Rate ◽  
First Generation ◽  
Second Generation ◽  
Fasciola Hepatica ◽  
The Other ◽  
Lymnaea Truncatula

AbstractAdult Lymnaea truncatula were subjected to 10 days of experimental desiccation and then remained in water for 1 or 8 days before each was exposed to a single miracidium. The infection rate was lower in these snails than in infected controls that were not exposed to stress (52–54% vs 73%). The redial burden clearly decreased in stressed snails (18–25 rediae per snail) than in controls (43 rediae). This numerical decrease concerned essentially: i) live independent rediae of the first generation and the first cohort of the second generation, and ii) dependent rediae of subsequent generations. Mature rediae were more numerous in the first cohort of the second generation than in the other generations. Desiccation before exposure limited the size of the redial burden but placement in water for 8 days just after the stress attenuated the effects of this factor.

Effect of concurrent infection with Muellerius capillaris on the development of redial generations of Fasciola hepatica in Lymnaea truncatula

1992 ◽  
Vol 66 (2) ◽  
pp. 108-117 ◽  
Author(s):  
P. Hourdin ◽  
D. Rondelaud ◽  
J. Cabaret
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Fasciola Hepatica ◽  
Single Infection ◽  
Concurrent Infection ◽  
Double Infection ◽  
Lymnaea Truncatula ◽  
Early Cohort ◽  
Muellerius Capillaris

ABSTRACTThe rediae of Fasciola hepatica were counted according to generation in adult and juvenile Lymnaea truncatula following single infection with Fasciola hepatica, double infection with F. hepatica and then Muellerius capillaris, or double infection with M. capillaris and F. hepatica. The rediae found in double infections were essentially first generation and an early cohort from the second generation. The following differences were observed in adult snails which underwent double infection when compared to corresponding single infections: i) dependent rediae were almost completely absent; ii) degenerating independent rediae were found in identical or decreased numbers; iii) living independent rediae of the first generation were decreased in number, while those of the second generation had variable decreased numbers. The results were similar in juvenile snails with double infections, except that the numbers of degenerating independent rediae were higher than those found in corresponding single infections and the numbers of rediae of the second generation were increased. The order of exposure in double infections had no influence on the number and maturation of fasciolid rediae.

The role of style in the ethnolect: Style-shifting in the use of ethnolectal features in first- and second-generation speakers

2020 ◽  
Vol 24 (4) ◽  
pp. 861-880 ◽  
Author(s):  
Ksenia Gnevsheva
Keyword(s):  
Design Methodology ◽  
First Generation ◽  
Second Generation ◽  
The Other ◽  
Research Questions ◽  
Similarities And Differences ◽  
Style Shifting ◽  
Australian English ◽  
First And Second Generation

Aims and Objectives/Purpose/Research Questions: The paper aimed to investigate style-shifting in the use of ethnolectal features in first- and second- generation bilingual migrants. Design/Methodology/Approach: Three groups of speakers (first- and second-generation Russian–English bilinguals as well as monolingual Anglo Australians) were audio-recorded in three different styles (conversation, interview, and reading). Data and Analysis: Their production of the goose and trap vowels across the styles was analyzed quantitatively. Findings/Conclusions: Overall differences were found between the groups such that first- and second-generation speakers produced more Russian-like vowels compared to the monolinguals; with the biggest differences between the first-generation speakers and the other two groups. In terms of style-shifting, no significant differences were found in the monolingual speakers, and both first- and second-generation speakers were found to produce most Australian English-like vowels in the conversation style. At the same time, certain differences between the two bilingual groups surfaced, such as no significant differences in the first-generation speakers’ production of the goose vowel and in the vowels’ linguistic conditioning. Originality: Previous studies have compared ethnolects in the first- and second-generations of migrants and mainstream varieties in order to theorize ethnolect formation. Several studies have also investigated intraspeaker style-shifting between more ‘mainstream’ and more ‘ethnic’ in ethnolect speakers, but such style-shifting is rarely compared across generations. Significance/Implications: The similarities and differences between the two bilingual groups suggest that ethnolectal features may be originally derived from the community language but may be reallocated to other sociolinguistic meanings in the second generation.

Cercarial productivity of redial generations in single-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or Fasciola hepatica

2000 ◽  
Vol 74 (1) ◽  
pp. 1-5 ◽  
Author(s):  
M. Abrous ◽  
D. Rondelaud ◽  
G. Dreyfuss
Keyword(s):  
Fasciola Hepatica ◽  
The Other ◽  
Redial Generation ◽  
Post Exposure ◽  
Laboratory Conditions ◽  
Lymnaea Truncatula

AbstractSingle-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or with Fasciola hepatica were carried out under laboratory conditions to count free rediae, their germinal embryos, and to determine the cercarial productivity of each redial generation. In snails infected by P. daubneyi, the cercariae were produced by the first (8.7 cercariae per redia) and second (8.9 per redia) generations. At day 63 post-exposure, they corresponded, respectively, to 53.9% and 46.1% of cercariae produced by all rediae. In snails infected by F. hepatica, the majority of cercariae were produced by the R2a group (18.2 cercariae per redia) and corresponded to 66.0% of cercariae produced all rediae. The cercariae produced by the other redial groups were more limited in number: 17.5 per redia in the R1b group (28.7%) and 2.0 per redia in the R2b/R3a group (5.3%). Cercarial productivity of P. daubneyi until day 63 post-exposure was more limited in number than that of F. hepatica: a total of 145 cercariae per snail versus 427 per snail.

scholarly journals Industrial Hubs as Development Incubators

2020 ◽  
pp. 521-558
Author(s):  
Arkebe Oqubay
Keyword(s):  
South Korea ◽  
East Asia ◽  
First Generation ◽  
Second Generation ◽  
East Asian ◽  
The Other ◽  
Stages Of Development ◽  
Industrial Policies ◽  
Catch Up ◽  
East Asian Economies

Contemporary industrial hubs evolved in East Asia after the 1950s and have been associated with the industrial catch-up of the East Asian economies and their industrial policies. This chapter has three main objectives: to depict the path of hubs development in these pioneering economies and provide a synthesis of the East Asian experience; to extract relevant lessons for policymakers and practitioners; and to provide a perspective on how industrial hubs can synergize industrialization and technological catch-up. Although there are commonalities, experiences have been uneven across these economies with different stages of development. The experiences of the first-generation industrial hubs, namely, Taiwan (China), South Korea, and Singapore are reviewed, followed by China as the second generation. A synthesis, key observations, and conclusions are reviewed. The chapter will complement the other chapters under Part IV through synthesis and lessons, while it complements the analytical perspectives under Parts I and II of the Handbook, by building on arguments and conceptual perspectives.

scholarly journals STUDY OF MOLLUSCS’ INFESTATION WITH FASCIOLA HEPATICA IN BRYANSK REGION

2019 ◽  
pp. 481-486
Author(s):  
Postevoy ◽  
Andreyanov ◽  
Puzanova
Keyword(s):  
Intermediate Host ◽  
Infection Rate ◽  
Fasciola Hepatica ◽  
Pond Snail ◽  
Stages Of Development ◽  
Larval Stages ◽  
Development Cycle ◽  
Lymnaea Truncatula

The intermediate host of Fasciola hepatica is Lymnaea truncatula mollusk. However, participation of other species of mollusks (L. stagnalis, Galba palustris, etc.) in the development cycle of F. hepatica is not excluded. In this connection, we have studied the distribution of mollusks of these species in the territory of the Bryansk region. The aim of the work was to carry out a study on the invasion of fasciol larvae of mollusks on pastures of trematodiasis-unfriendly farms of the Bryansk region. On farms, the density of mollusks and their species, as well as the dynamics of the infection of mollusks by the partenite stages of F. hepatica, were determined. The work was carried out from May to October 2018 on 3 pastures with an area of 2 to 5 hectares. The study was subjected to mollusks: small pond snail L. truncatula in the amount of from 149 to 151 specimens, ordinary pond snail – L. stagnalis from 10 to 18 specimens, marsh pond snail – L. palustris from 30 to 85 specimens, iushkoviy pond snail – L. auricularia from 4 to 21 specimens. Mollusks were examined every month during the pasture period (May-October) for infection with fasciol larvae by the compressor method. It was revealed that only small pond snail L. truncatula was infested by the larval stages of development of fasciol. The rest of the limneids were free from this trematodase invasion. The small pond snail was infected more intensely in September. The fasciol larvae of the small pond snail were recorded in May, June, August and September; the infection rate was 1.3%, 2.6%, 6.6% and 8%, respectively.

scholarly journals 156 Effects of the Inductive Period, Shoot Density, and Leaf Removal on the Flowering of Heliconia rostrata Ruiz & Pavon

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 416E-417
Author(s):  
Norberto Maciel ◽  
Richard A. Criley
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Shoot Density ◽  
The Other ◽  
Leaf Removal ◽  
The Third ◽  
Intact Plants ◽  
The Relationship ◽  
Inductive Period ◽  
Short Days

Heliconia rostrata is a herbaceous-musoid sympodial rhizomatous plant that grows as clump. After three leaves are produced, each shoot of the clump may bear an inflorescence if it is induced by short days (SD). However, the relationship between shoot density and flowering has not been quantified. To evaluate the effects of the inductive period, number of shoots, and leaf removal on flowering, rhizomes were planted in 120 pots (8 L). One-third of the pots were planted with two rhizomes, while the remainder was planted with one. One-half of the pots with one rhizome were allowed to develop all their shoots for three generations, while in the remaining pots only one shoot per generation was allowed to grow. In addition, one-half of the plants in all the treatments were subjected to selective leaf removal. The plants were grown under long days (LD) >13 h in a glasshouse until four leaves were produced. Inductive SD was supplied to all the plants from 5:00 pm to 8:00 am. After 8 weeks of SD, one-half of the plants were given LD, while the other half continued under SD (conSD) until flowering. The highest percentage of flowering shoots (39% to 35%) was observed in plants under conSD; plants under SD-LD were 10% to 9%. The second generation of shoots showed the highest flowering (74% conSD and 21% SD-LD), followed by the first (62% conSD and 18% SD-LD), and third (31% conSD and 0% SD-LD) generations. Non-flowering shoots of the first generation were aborted or dead. Shoots of the third were still vegetative, since they had few leaves to be induced. Fewer flowers occurred in clumps allowed to develop all their shoots. Intact plants from rhizomes with one shoot per generation flowered more than the partially defoliated ones under conSD.

scholarly journals Estimation of Accurate and New Method for Hemodialysis Dose Calculation

2008 ◽  
Vol 1 ◽  
pp. CMU.S771
Author(s):  
Ahmad T. Azar
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Dose Calculation ◽  
The Other ◽  
New Method ◽  
Dialysis Patients ◽  
Dialysis Dose ◽  
New Formula ◽  
Hemodialysis Dose

Background The Kt/V value demonstrates the dose of hemodialysis (HD). However, because of several existing methods for calculating delivered dialysis dose, Kt/V values can, in fact, be different for the same set of pre-/post-dialysis blood urea concentrations. Methods In the study presented here, another formula was derived for calculating Kt/V from the pre- and post-dialysis BUN. We prospectively compared the Kt/V values obtained using this new formula and the Kt/V values obtained via the other existing formulae to see whether reliance on the latter approach was likely to lead to errors in over- or underprescribing dialysis regimens. Data were processed on 268 dialysis patients. Results The estimated Kt/V (Kt/Vest) values were statistically different (p < 0.05) from the calculated Kt/V values from other models, except for those Kt/V values calculated according to the lowrie (P = 0.112), Keshaviah (P = 0.069), Daugirdas First Generation (P = 0.059), Basile (P = 0.102), Ijely (P = 0.286) and Daugirdas Second Generation (P = 0.709). The best correlations were seen with the Daugirdas second generation formula (R = 0.958 and R2 = 0.919). Conclusion Since the best correlations were seen between Kt/Vest and the Daugirdas second generation Kt/V we can demonstrate that these two models are more accurate than the other models.

Redial generations ofFasciola hepatica: a review

2009 ◽  
Vol 83 (3) ◽  
pp. 245-254 ◽  
Author(s):  
D. Rondelaud ◽  
M. Belfaiza ◽  
P. Vignoles ◽  
M. Moncef ◽  
G. Dreyfuss
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Fasciola Hepatica ◽  
Abnormal Development ◽  
Third Generation ◽  
Biotic Factors ◽  
Snail Infection ◽  
Developmental Patterns ◽  
The Third

AbstractAn update on the redial generations ofFasciola hepaticawas carried out to highlight the different developmental patterns of rediae, the effects of some factors on these generations, and the consequences of such developmental patterns on cercarial productivity. The development of generations is dependent on the behaviour of the first mother redia of the first generation. If this redia remains alive throughout snail infection, it produces most second-generation rediae. In contrast, if it dies during the first weeks, daughter redia formation is ensured by a substitute redia (the second mother redia of the first generation, or the first redia of the second generation). Environmental and biotic factors do not modify the succession of redial generations, but most act by limiting the numbers of rediae, either in all generations, or in the second and/or third generations. An abnormal development of rediae reduces the number of cercariae and most are formed by the second cohort of the first generation. By contrast, most cercariae are produced by the first cohort of the second generation when redial development is normal. The mother rediae described by previous authors might correspond to the first generation and the second cohort of the second generation, while daughter rediae would be the second cohort of the second generation and the first cohort of the third generation. Under certain circumstances, daughter redia formation is ensured by the first two mother rediae or all first-generation rediae, thus demonstrating that the first mother redia is not the only larva to ensure daughter redia formation.

Larval development of Fasciola hepatica in experimental infections: variations with populations of Lymnaea truncatula

2002 ◽  
Vol 76 (2) ◽  
pp. 179-183 ◽  
Author(s):  
P. Vignoles ◽  
G. Dreyfuss ◽  
D. Rondelaud
Keyword(s):  
Retrospective Study ◽  
Genetic Variability ◽  
Larval Development ◽  
Experimental Infection ◽  
Fasciola Hepatica ◽  
The Other ◽  
Mammalian Host ◽  
Cercarial Production ◽  
Lymnaea Truncatula ◽  
Low Prevalence

AbstractA retrospective study was undertaken on 70 French populations of Lymnaea truncatula experimentally infected with Fasciola hepatica to determine whether or not susceptibility of snails to infection influenced redial and cercarial production. Results were compared with those obtained from two control populations, known for prevalences higher than 60% when experimentally infected with F. hepatica. In the 70 other populations examined, the prevalences ranged from 2 to 75%. In 55 of these populations, where the prevalence was more than 20%, a high proportion (50.1–56.8%) of snails died after cercarial shedding, whereas in the other groups (non-shedding snails with the most differentiated larvae being free cercariae, rediae containing cercariae, immature rediae, or sporocysts, respectively), snail death was significantly less. In 11 populations, where the prevalence values were 5–19%, only 14% of snails died after cercarial shedding, whereas snails with free cercariae, rediae with cercariae, or immature rediae showed significant increases in snail mortality. In the remaining four snail populations, with prevalences of less than 5%, the most differentiated larval forms were only immature rediae and/or sporocysts. Overall, the number of rediae containing cercariae significantly decreased with decreasing prevalence values. The low prevalence of experimental infection in several populations of snails might be explained by the occurrence of natural infections with miracidia originating from a mammalian host other than cattle, and/or by genetic variability in the susceptibility of snails to infection.

Redial generations of Fasciola gigantica in the pulmonate snail Lymnaea truncatula

1992 ◽  
Vol 66 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Rakotondravao ◽  
A. Moukrim ◽  
P. Hourdin ◽  
D. Rondelaud
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Histological Study ◽  
Fasciola Gigantica ◽  
Pulmonate Snail ◽  
Lymnaea Truncatula ◽  
The Mean

ABSTRACTLymnaea truncatula, 4 mm in height, were subjected to infection by a single miracidium of Fasciola gigantica, then raised at 23°C until day 60 of the experiment. Histological study of these snails demonstrated a mean redial burden of 34 parasites at day 60, of which one third were degenerating forms. The mean number of living independent rediae did not exceed 5 for the first and second generations. Conversely, in subsequent generations there were as many as 18 rediae per snail at day 60. The first living redia of the first generation in particular gave rise to daughter rediae. Mature rediae appeared at day 35 and especially concerned the first and second generations at day 60. The authors conclude that development of the first and second redial generations occurs during the same period, and that the forms of the first cohort of the second generation are produced from the first redia of the first generation which originated from the sporocyst.

Sign in / Sign up

Export Citation Format

Share Document