Lymnaea glabra: progressive increase in susceptibility to Fasciola hepatica through successive generations of experimentally infected snails

2014 ◽  
Vol 89 (4) ◽  
pp. 398-403 ◽  
Author(s):  
D. Rondelaud ◽  
F.F. Djuikwo Teukeng ◽  
P. Vignoles ◽  
G. Dreyfuss

AbstractExperimental infections of Lymnaea glabra (two populations) with Fasciola hepatica were carried out during seven successive snail generations, to determine if prevalence and intensity of snail infection increased over time through descendants of snails already infected with F. hepatica. Controls were descendants coming from uninfected parents and infected according to the same protocol. No larval forms were found in the bodies of control snails coming from uninfected parents. In contrast, prevalence and intensity of F. hepatica infection in snails originating from infected parents progressively increased from the F2 or F3 to the F6 generation of L. glabra. In another experiment carried out with the F7 generations of L. glabra and a single generation of Galba truncatula (as controls), the prevalence of F. hepatica infection and the total number of cercariae were lower in L. glabra (without significant differences between both populations). If the number of cercariae shed by infected snails was compared to overall cercarial production noted in snails containing cercariae but dying without emission, the percentage was greater in G. truncatula (69% instead of 52–54% in L. glabra). Even if most characteristics of F. hepatica infection were lower in L. glabra, prevalence and intensity of parasite infection increased with snail generation when tested snails came from infected parents. This mode of snail infection with F. hepatica suggests an explanation for cases of fasciolosis occurring in cattle-breeding farms where paramphistomosis is lacking and G. truncatula is absent.

2012 ◽  
Vol 88 (1) ◽  
pp. 105-111 ◽  
Author(s):  
D. Rondelaud ◽  
R. Mouzet ◽  
P. Vignoles ◽  
G. Dreyfuss ◽  
J. Cabaret

AbstractSeveral experiments on the breeding of trematode-infected Galba truncatula for obtaining and packaging Fasciola hepatica and Paramphistomum daubneyi metacercariae were carried out to determine the more convenient methods to use for commercial production of these infective stages. Compared to the breeding of infected snails in aquaterraria, the use of 14-cm Petri dishes allowed a greater prevalence of snail infection and a higher number of metacercariae. The production of these larvae was still 2.3–3.4 times greater if infected snails were dissected during the patent period. The aspiration of these metacercariae at the extremity of a Pasteur pipette significantly shortens the time necessary for their transfer from Petri dishes to Eppendorf tubes. Using 14-cm Petri dishes, snail dissection and metacercarial aspiration for their transfer strongly reduce the cost price for metacercarial production of the trematodes Fasciola hepatica and Paramphistomum daubneyi.


2009 ◽  
Vol 84 (1) ◽  
pp. 77-80
Author(s):  
P. Vignoles ◽  
F. Aimeur ◽  
A. Titi ◽  
D. Rondelaud ◽  
A. Mekroud ◽  
...  

AbstractExperimental infections of pre-adult Galba truncatula (two populations) using one, two, three or five miracidia of Fasciola hepatica per snail were carried out to determine the total number of cercariae produced by snails when they were sacrificed at day 70 post-exposure (at 24°C). When the number of miracidia used for each snail increased at exposure, significant numerical augmentations of live rediae and of intraredial differentiating cercariae were noted. In contrast, only insignificant differences between mean numbers of free cercariae were found. The number of metacercariae produced by each snail (after shedding and/or after dissection) increased in infections with up to three miracidia per snail in each population and strongly decreased in infections with five miracidia per snail. Compared to the other types of infections, the delay of cercarial differentiation noted in the five-miracidia groups was probably due to the volume of the snail host, which would be too small to assure the complete development of five sporocysts.


1982 ◽  
Vol 12 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Kamlesh R. Patel ◽  
Graeme P. Berlyn

Embryo expiants ofPinuscoulteri D. Don. were cultured on agar media (modified from Campbell and Durzan 1975) only supplemented with 2.25 mg•L−1 of benzyl amino purine (BAP). Nuclear DNA contents were measured in cells of the embryo explants, callus, and buds regenerated from these explants, and sand-germinated seedlings. Measurements were made at weekly intervals during 6 weeks of culture. Absolute amounts of cellular DNA were determined with a microspectrophotometer using chicken erythrocytes as an internal standard. Initially, the nuclei had a DNA level between 2C and 4C with a mean of 3C. The sand-grown seedlings remained within this range, with an increased frequency of 4C nuclei in the 6-week seedlings. However, cells from callus and regenerated buds showed a progressive increase in DNA level over time. After 42 days in culture, the buds contained large populations of cells at the 8C level and a considerable number of cells with DNA levels above 8C. In addition, the nuclei showed a considerable increase in chromosomal aberrations including bridges, micronuclei, lagging chromosomes, and fragmentation. Nuclear volume also increased over time in the regenerated buds. It is therefore concluded that culture conditions, perhaps cytokinin content, increased the levels of nuclear DNA. These increased levels could be the result of polyploidy, polyteny, hyperaneuploidy, or a combination of these types of nuclear organization.


2019 ◽  
Vol 57 ◽  
pp. 60-67
Author(s):  
G. D. Іlyashenko

Dairy cattle breeding is one of the leading livestock sectors whose purpose is to ensure the production of high quality dairy raw materials in volumes meeting the scientifically grounded standards of state food security and expanding the export potential of the agrarian sector. The purpose of our research was to study the status and prospects of dairy cattle breeding in the Kirovograd region. Material and methods of research. The research was carried out on the basis of the electronic database of breeding goals (including 2312 cows), official statistics and estimates of cattle of various breeds that are involved in the production of dairy direction in the breeding farms of the Kirovograd region. The analysis used zootechnical and statistical methods. The calculations were carried out using the software package "STATISTICA-6,1" Results. According to the research (2001–2018), the cattle population in the Kirovograd oblast decreased by a factor of 2.6. Thus, as of January 1, 2018, its number constituted 96.3 thousand heads in all categories of farms, 53.1 thousand of them were cows, the number of which also decreased by 2.4 times. Specific gravity of cattle population of farms remains significant and makes up 72.7%, and 80.6% in the livestock of cows. The largest number of cows of agricultural enterprises declined significantly. Thus, as of January 1, 2018, their number was 10.3 thousand goals, which is 4.7 times less than in the same period of 2001. In the households there is also a tendency for a permanent reduction of cows, the difference is, respectively, 37.0 thousand heads or 46.4% The development of dairy cattle breeding is characterized by two opposite tendencies: reduction of livestock of cows and increase of their productivity. Thus, in agricultural enterprises in 2010, compared to 2000, hopes per cow increased by 2.5 times, in all categories of farms by 1.8 times. In 2017, the increase in dairy costs in agricultural enterprises compared to 2010 amounted to 60.0% in farms of all categories 12.2%. The researches found that in the agricultural enterprises of the oblast as of January 1, 2018 there are 26256 head of cattle, including 10281 cows. The breeding part of the existing cows is 3.013 heads, 29.3% of the total number located in 10 breeding farms. The analysis of the genealogy structure showed that the experimental population of cows belongs to 18 lines and related groups of which the most numerous Chifa 1427381 – 20.4%, Starbuck 352790 – 20.1%, Henev 1629391 – 18.6% , Eleusis 1491007 – 11.2%, Family 267150 – 10.8%. Among the indicated lines, the lowest level of milk productivity was first-born cows. The 1491007, the milk of milk for 305 days of lactation was 4466 ± 99.8 kg, and the milk fat was 168.2 ± 6.5 kg. Analogues l Starbak 352779 was characterized by the highest milk productivity, its level was 5696 + 98.8 kg and 224.9 ± 9.7 kg, respectively. The difference in stomach was 1230 ± 140.4 kg (td = 10.2) and at the release of milk fat 56.7 ± 5.28 kg (td = 10.2) at P < 0.001. However, the latter were markedly less service life (125 against 168 days) and logically higher reproduction rate compared to other lines. An analysis of the intensity of the formation of live weight of young animals has been established for its highest growth in heifers of controlled herds in the period from 9 to 12 months. Thus, in animals of Ukrainian red breed, the growth rate of live weight during this period was 75 kg, Ukrainian red-shrimp 61 kg, Ukrainian black-and-white 73 kg, Holstein 76 kg. Accordingly, during this period, the average daily gain of live weight of young breeds of these breeds was 833 g; 678 g; 811 g, 835 g. The sharp fluctuations of average daily increments during growing periods, first of all, testify to the unequal conditions of growing and feeding young animals than the breed differences. In general, as a result of the analysis of the formation of live weight of heifers, a significant level of phenotypic variability was observed, which confirms sufficient genetic resources and preconditions for selection on the given sign. Therefore, proceeding from the above, in the long run, selection work for breeding improvement of cattle breeding farms of the Kirovograd region should be conducted in accordance with certain promising directions according to groups of breeds. Conclusions. A very important factor in the growth of milk production in the Kirovograd region is high-yield pedigree cattle. The main task on the way of bringing breeding cases in dairy farming to the modern level is the introduction of computer breeding records in breeding farms. This will allow to estimate in the near future bulls-pedigrees, which were used in the past in these farms, to allocate among them complex improvers for precisely the specific conditions and maximally attract them for reproduction. On the other hand, a reliable clogging of poor quality in the genetic sense of sperm production, which leads to negative consequences, will be posed. When establishing the assessment of the breeding value of bulls and developing a single plan of breeding and breeding work in the region, one can proceed to the next step of improving breeding and breeding business, introducing a progressive method of raising the breeding value of animals of large-scale breeding. As a result, the profit from the breeding of highly productive animals, well adapted to specific conditions, will significantly exceed the costs. At the same time, the proposed measures will allow the breeding business to be brought up to the modern world level and stimulate highly productive cattle breeding.


Parasitology ◽  
1999 ◽  
Vol 118 (4) ◽  
pp. 407-415 ◽  
Author(s):  
C. D. M. MÜLLER-GRAF ◽  
M. E. J. WOOLHOUSE ◽  
C. PACKER

Infection with the cestode Spirometra spp. was studied in 2 populations of lions in the Serengeti and the Ngorongoro Crater in Tanzania, East Africa. These 2 lion populations lived in different habitats and were known to differ genetically: lions in the Serengeti were outbred, whereas lions in the Ngorongoro Crater were inbred. Faecal samples were collected from 112 individually known lions between March 1991 and November 1992. Over 60% of lions were infected and the median intensity of infection was 975 eggs per g of faeces. The distribution of egg counts was overdispersed. There was variability through time, though this was unrelated to seasons delimited by rainfall. There were no significant differences in levels of infection between age classes; cubs less than 9 months were already heavily infected. Sex and reproductive status did not have a significant effect. However, there were significant differences in intensities of infection between the Crater and the Serengeti populations – Spirometra spp. showed a higher level of infection intensity in the Crater population – with some variation between prides within these populations. Allozyme heterozygosity scores were available for a subset of 28 lions but were unrelated to levels of Spirometra infection. It was not possible to ascribe differences in levels of parasite infection to genetic rather than ecological factors.


Author(s):  
Liliana María Favre

This chapter discusses software evolution, challenges and strategic directions in the context of MDA. Various authors agreed that it is difficult to define completely software and then, software evolution. Software is certainly more that bits stored in a file, it is an abstract idea that encompasses the concepts, algorithms embodied in the implementation as well as all its associated artifacts and processes. Research seems to confirm that computer software and process software have much in common. Osterweil (2003) assures that software processes are software too. In other paper (Osterweil, 2007), he suggests analyzing the nature of software and proposes to define taxonomies for exploring characteristics and approaches to the development, verification of qualities and software evolution. The exploration of these questions is an important current of software engineering research. On the other hand, evolution is defined as a process of gradual change and development from fewer and simpler forms to higher, more complex, or better ones. In biology, evolution is related to develop over time often many generations, into forms that are better adapted to survive changes in their environment. Thus, evolution captures the notion of something improving and changes occur in species in successive generations, i.e. individuals get old and species evolve. Jazayeri (2005) analyzes the definition of software evolution. The concept of “specie” in software may be associated to meta-levels describing families (species) of software systems. These meta-levels or architectures are created as improvements to previous existing ones and describe evolved families of software systems.


2018 ◽  
Vol 15 (17) ◽  
pp. 5343-5363 ◽  
Author(s):  
Alessandra D'Angelo ◽  
Federico Giglio ◽  
Stefano Miserocchi ◽  
Anna Sanchez-Vidal ◽  
Stefano Aliani ◽  
...  

Abstract. High-latitude regions are warming faster than other areas due to reduction of snow cover and sea ice loss and changes in atmospheric and ocean circulation. The combination of these processes, collectively known as polar amplification, provides an extraordinary opportunity to document the ongoing thermal destabilisation of the terrestrial cryosphere and the release of land-derived material into the aquatic environment. This study presents a 6-year time series (2010–2016) of physical parameters and particle fluxes collected by an oceanographic mooring in Kongsfjorden (Spitsbergen, Svalbard). In recent decades, Kongsfjorden has been experiencing rapid loss of sea ice coverage and retreat of local glaciers as a result of the progressive increase in ocean and air temperatures. The overarching goal of this study was to continuously monitor the inner fjord particle sinking and to understand to what extent the temporal evolution of particulate fluxes was linked to the progressive changes in both Atlantic and freshwater input. Our data show high peaks of settling particles during warm seasons, in terms of both organic and inorganic matter. The different sources of suspended particles were described as a mixing of glacier carbonate, glacier siliciclastic and autochthonous marine input. The glacier releasing sediments into the fjord was the predominant source, while the sediment input by rivers was reduced at the mooring site. Our time series showed that the seasonal sunlight exerted first-order control on the particulate fluxes in the inner fjord. The marine fraction peaked when the solar radiation was at a maximum in May–June while the land-derived fluxes exhibited a 1–2-month lag consistent with the maximum air temperature and glacier melting. The inter-annual time-weighted total mass fluxes varied by 2 orders of magnitude over time, with relatively higher values in 2011, 2013, and 2015. Our results suggest that the land-derived input will remarkably increase over time in a warming scenario. Further studies are therefore needed to understand the future response of the Kongsfjorden ecosystem alterations with respect to the enhanced release of glacier-derived material.


2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
Virginie Fabre ◽  
Silvana Condemi ◽  
Anna Degioanni ◽  
Estelle Herrscher

During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.


2018 ◽  
Vol 56 (1) ◽  
pp. 118-133 ◽  
Author(s):  
Faten Ghosn ◽  
Alex Braithwaite ◽  
Tiffany S Chu

How do individuals’ personal experiences with various aspects of political violence affect their attitudes toward hosting conflict refugees? More specifically, how do their personal exposure to violence, their own personal experience of being displaced, and their recent contact with refugees influence these attitudes? To explore answers to these questions, we draw upon a recent survey of 2,400 Lebanese residents where we identify individuals who experienced violence during the Lebanese civil war (1975–90), those forced to flee their homes during that conflict, and those who enjoy recent contact with Syrian immigrant and/or displaced populations. We examine whether these distinct experiences affect respondents’ regard for members of the Syrian refugee population. Results demonstrate that historical exposure to violence and experience of displacement have no discernible impact on individual attitudes toward hosting refugees. We find much stronger evidence that attitudes are associated with whether individual respondents have had contact with Syrians in Lebanon; those with such interactions are significantly more likely to support hosting refugees, to consider hiring a refugee, or to allow one of their children to marry a refugee. Our findings suggest exposure to violence by itself does not correlate to positive sentiments toward refugees, especially over time. Further, finding ways to create positive contact between refugees and native populations may be associated with improving attitudes and relations between the two populations.


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