Temperature thresholds and statistical modelling of larval Wuchereria bancrofti (Filariidea: Onchocercidae) developmental rates

Parasitology ◽  
1997 ◽  
Vol 114 (2) ◽  
pp. 123-134 ◽  
Author(s):  
F. LARDEUX ◽  
J. CHEFFORT
Keyword(s):  
Wuchereria Bancrofti ◽  
Developmental Rate ◽  
Statistical Modelling ◽  
Original Method ◽  
Frequency Data ◽  
Larval Stages ◽  
A Value ◽  
Temperature Thresholds ◽  
Developmental Rates ◽  
Aedes Polynesiensis

Developmental rates for Wuchereria bancrofti larvae maturing in the vector Aedes polynesiensis were estimated by analysing stage-frequency data consisting of counts of larval stages in mosquitoes reared at 20, 22·5, 25, 27·5, 30 and 32 °C. Base temperatures (i.e. low temperature thresholds) for W. bancrofti development were estimated by the x-intercept method and the model of Lactin et al. (1995). Resulting values were similar with both methods and were ≈12·5 °C for microfilariae (mf) in thorax, ≈17 °C for L1, 15·5 °C for L2 and 16·5 °C for L3. Upper thresholds estimated by the Lactin et al. model were 29·3 °C for mf, 29·1 °C for L1, 32·2 °C for L2 and 31·5 °C for L3. In addition, an original method was devised for computing the L3 upper threshold, by modelling L3 length shrinkage with temperature. It gave a value of 31·4 °C. At 32 °C, L2 and L3 stages exhibited altered morphology, larvae being shorter and wider than expected. The model of Lactin et al. described adequately the non-linear relationship between developmental rate and temperature, but a linear degree-day approach may be applied for temperatures below 27–28 °C.

scholarly journals 43IMPROVED IN VITRO DEVELOPMENT OF PORCINE NUCLEAR TRANSFER EMBRYOS WITH 6-DMAP FOLLOWING FUSION

2004 ◽  
Vol 16 (2) ◽  
pp. 144
Author(s):  
G.-S. IM ◽  
L. Lai ◽  
Z. Liu ◽  
Y. Hao ◽  
C.M. Murphy ◽  
...  
Keyword(s):  
Nuclear Transfer ◽  
Electric Pulse ◽  
Developmental Rate ◽  
Cell Number ◽  
Blastocyst Stage ◽  
In Vitro Development ◽  
Electric Pulses ◽  
Developmental Rates ◽  
Vitro Development

Although nuclear transfer (NT) has successfully produced cloned piglets, the development to blastocyst and to term is still low. Activation of the NT embryos is one of the key factors to improve the developmental ability of porcine NT embryos. Electric pulses as well as chemicals have been used to activate porcine NT embryos. This study was conducted to investigate the effect of continued activation following fusion pulses on in vitro development of porcine NT Embryos. Oocytes derived from a local abattoir were matured for 42 to 44h and enucleated. Ear skin cells were obtained from a 4-day-old transgenic pig transduced with eGFP recombinant retrovirus. Enucleated oocytes were reconstructed and cultured in PZM-3 in a gas atmosphere of 5% CO2 in air. Cleavage and blastocyst developmental rates were assessed under a stereomicroscope on Day 3 or 6. Blastocysts were stained with 5μg of Hoechst 33342 and total cell number was determined with an epifluorescent microscope. In Experiment 1, oocytes were activated with two 1.2kV/cm for 30μs (E) in 0.3M mannitol supplemented with either 0.1 or 1.0mM Ca2+. In each treatment, activated oocytes were divided into three groups. The first group was control (E). Other two groups were exposed to either ionomycin and 6-DMAP (E+I+D) or 6-DMAP (E+D) immediately after the electric pulses. In Experiment 2, fusion was conducted by using 1.0mM Ca2+ in the fusion medium. Fused NT embryos were divided into three treatments. NT embryos were fused and activated simultaneously with electric pulse as a control (C); the second group was treated with 6-DMAP immediately after fusion treatment (D0); and the third group was treated with 6-DMAP at 20min (D20) after fusion. In experiment 1, for 0.1mM Ca2+, developmental rates to the blastocyst stage for E, E+I+D or E+D were 12.5, 26.7 and 22.5%, respectively. For 1.0mM Ca2+, developmental rates to the blastocyst stage were 11.4, 28.3 and 35.6%, respectively. The activated oocytes treated with 6-DMAP following the electric pulses by using 1.0mM Ca2+ in fusion medium had higher (P<0.05) developmental rates to the blastocyst stage. In Experiment 2, developmental rates to the blastocyst stage for C, D0 or D20 were 10.0, 12.3, and 19.9%, respectively. Developmental rate to the blastocyst stage was higher (P<0.05) in D20. Fragmentation rates were 19.9, 10.8, and 9.0%, respectively. Regardless of Ca2+ concentration in fusion medium, continued treatments with chemicals following electric pulses supported more development of porcine activated oocytes. Treating NT embryos with 6-DMAP alone after fusion was completed by using 1.0mM Ca2+ in fusion medium improved the developmental rates to the blastocyst stage and prevented fragmentation accompanied by electric fusion. This study was supported by NIH NCRR 13438 and Food for the 21st Century.

Prevalence of Wuchereria bancrofti Infection in Mosquitoes from Pangani District, Northeastern Tanzania

2019 ◽  
Vol 1 (1) ◽  
pp. 30-34
Author(s):  
Godlisten S. Materu
Keyword(s):  
Anopheles Gambiae ◽  
Disease Burden ◽  
Mosquito Control ◽  
Anopheles Funestus ◽  
Wuchereria Bancrofti ◽  
Mosquito Vectors ◽  
Larval Stages ◽  
Polymerase Chain ◽  
Control Light ◽  
Susceptibility Profiles

Background: Wuchereria bancrofti is the most widely distributed of the 3 nematodes known to cause lymphatic filariasis, the other 2 being Brugia malayi and Brugia timori. Anopheles gambiae and Anopheles funestus are the main vectors. However, the relative contributions of mosquito vectors to disease burden and infectivity are becoming increasingly important in coastal East Africa, and this is particularly true in the urban and semiurban areas of Pangani District, Tanzania. Methods: Mosquitoes were sampled from 5 randomly selected villages of Pangani District, namely, Bweni, Madanga, Meka, Msaraza, and Pangani West. Sampling of mosquitoes was done using standard Centers for Disease Control light traps with incandescent light bulbs. The presence of W. bancrofti in mosquitoes was determined via polymerase chain reaction (PCR) assays using NV1 and NV2 primers, and PoolScreen 2 software was used to determine the estimated rate of W. bancrofti infection in mosquitoes. Results: A total of 951 mosquitoes were collected, of which 99.36% were Culex quinquefasciatus, 0.32% were Anopheles gambiae, and 0.32% other Culex species. The estimated rate of W. bancrofti infection among these mosquitoes was 3.3%. Conclusion: This was the first study employing the use of PoolScreen PCR to detect W. bancrofti circulating in mosquito vectors in Pangani District, northeastern Tanzania. The presence of W. bancrofti infection suggests the possibility of infected humans in the area. The high abundance of Cx. quinquefasciatus calls for integrated mosquito control interventions to minimise the risk of W. bancrofti transmission to humans. Further research is required to gain an in-depth understanding of the W. bancrofti larval stages in mosquitoes, their drug sensitivity and susceptibility profiles, and their fecundity.

Developmental divergence among hatchery strains of rainbow trout (Salmo gairdneri). II. Hybrids

1985 ◽  
Vol 27 (3) ◽  
pp. 298-307 ◽  
Author(s):  
Moira M. Ferguson ◽  
Roy G. Danzmann ◽  
Fred W. Allendorf
Keyword(s):  
Rainbow Trout ◽  
First Generation ◽  
Developmental Rate ◽  
Salmo Gairdneri ◽  
Maternal Parent ◽  
Reciprocal Hybrids ◽  
Hatching Time ◽  
Developmental Rates ◽  
Developmental Divergence ◽  
Additive Genetic Effects

The developmental rates of first generation hybrids between six closely related hatchery strains of rainbow trout are compared using hatching time, morphology, and the pattern of ontogenetic change of four enzymes. Hybrid developmental rates can not be explained by additive genetic effects. Nine of 14 hybrid types developed slower than their maternal parent. These results are consistent with a hypothesis of regulatory divergence between the hybridizing strains. Heterotic effects were observed in five hybrid groups in that hybrids developed faster than their maternal parent. A strong dominance component was observed in the reciprocal hybrids of one strain. There was no association between the degree of perturbation of hybrid developmental rates and the genetic distance between hybridizing strains. Hybrids between more distantly related strains were no more delayed in their development than those from closely related strains.Key words: developmental rate, rainbow trout, hybrids, gene regulation.

scholarly journals Embryonic communication in the nest: metabolic responses of reptilian embryos to developmental rates of siblings

2011 ◽  
Vol 279 (1734) ◽  
pp. 1709-1715 ◽  
Author(s):  
Jessica K. McGlashan ◽  
Ricky-John Spencer ◽  
Julie M. Old
Keyword(s):  
Developmental Stages ◽  
Incubation Temperature ◽  
Developmental Rate ◽  
Freshwater Turtle ◽  
Heart Rates ◽  
Developmental Rates ◽  
Environmentally Cued Hatching ◽  
Developmental Asynchrony ◽  
Developmental Conditions ◽  
Australian Freshwater

Incubation temperature affects developmental rates and defines many phenotypes and fitness characteristics of reptilian embryos. In turtles, eggs are deposited in layers within the nest, such that thermal gradients create independent developmental conditions for each egg. Despite differences in developmental rate, several studies have revealed unexpected synchronicity in hatching, however, the mechanisms through which synchrony are achieved may be different between species. Here, we examine the phenomenon of synchronous hatching in turtles by assessing proximate mechanisms in an Australian freshwater turtle ( Emydura macquarii ). We tested whether embryos hatch prematurely or developmentally compensate in response to more advanced embryos in a clutch. We established developmental asynchrony within a clutch of turtle eggs and assessed both metabolic and heart rates throughout incubation in constant and fluctuating temperatures. Turtles appeared to hatch at similar developmental stages, with less-developed embryos in experimental groups responding to the presence of more developed eggs in a clutch by increasing both metabolic and heart rates. Early hatching did not appear to reduce neuromuscular ability at hatching. These results support developmental adjustment mechanisms of the ‘catch-up hypothesis’ for synchronous hatching in E. macquarii and implies some level of embryo–embryo communication. The group environment of a nest strongly supports the development of adaptive communication mechanisms between siblings and the evolution of environmentally cued hatching.

Variation in the vector competence of Aedes polynesiensis for Wuchereria bancrofti

Parasitology ◽  
1995 ◽  
Vol 111 (1) ◽  
pp. 19-29 ◽  
Author(s):  
A.-B. Failloux ◽  
M. Raymond ◽  
A. Ung ◽  
P. Glaziou ◽  
P. M. V. Martin ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Experimental Infection ◽  
Vector Competence ◽  
Geographic Origin ◽  
Wuchereria Bancrofti ◽  
Infective Stage ◽  
Intermediate Hosts ◽  
Mosquito Mortality ◽  
Aedes Polynesiensis ◽  
Different Levels

SUMMARYThe vector competences of 6 geographic strains of Aedes polynesiensis for Wuchereria bancrofti were studied using two types of experimental infections. Experimental infection of laboratory-bred mosquitoes fed on the carriers' forearms with different levels of microfilaraemia showed that microfilariae (mf) uptake was directly proportional to the carrier's mf density and, as mf densities decreased, concentration capacity of Ae. polynesiensis increased. It was also shown that infection has an important effect on mosquito mortality, and that the mortality rate differed among mosquito strains. In infections using artificial feeders, the mf uptake was closely regulated, thus showing differences in the vectorial efficiency of Ae. polynesiensis related to the geographic origin of the mosquito strain. The mosquitoes from the Society archipelago were more efficient intermediate hosts than geographically distant strains when infected with W. bancrofti from an island within the archipelago (Tahiti). Mosquito strains from the Society archipelago developed the highest proportion of infective-stage larvae and exhibited the lowest mortality rate when infected with sympatric Tahitian W. bancrofti.

scholarly journals Characterization of the larval stages of Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) using head capsule width

2001 ◽  
Vol 61 (1) ◽  
pp. 125-131 ◽  
Author(s):  
O. FRANCISCO ◽  
A. P. do PRADO
Keyword(s):  
Age Structure ◽  
Developmental Rate ◽  
Head Capsule ◽  
Larval Instars ◽  
Alphitobius Diaperinus ◽  
Larval Stages ◽  
Mean Width ◽  
The Mean ◽  
Coleoptera Tenebrionidae

The mean width (n = 5) of the cephalic capsule instar of Alphitobius diaperinus was determined. The larvae were reared at 27ºC (± 0.1ºC). The result showed that A. diaperinus has eight larval instars. The head capsule of the 1st instar larvae measured x = 0.228 (SD = 0.0192) and the last instar larval measured x = 1.339 (SD = 0.0436). The developmental rate, determined by Dyar-Hutchinson's rule, was 1.29. These data may be useful for studies on phenology and age structure of A. diaperinus in the field.

Timing of spawning and assessment of a degree-day model to predict the in situ embryonic developmental rate of white sucker, Catostomus commersoni

1997 ◽  
Vol 54 (9) ◽  
pp. 2040-2048 ◽  
Author(s):  
P Hamel ◽  
P Magnan ◽  
M Lapointe ◽  
P East
Keyword(s):  
Developmental Rate ◽  
Threshold Temperature ◽  
White Sucker ◽  
Catostomus Commersoni ◽  
Egg Hatching ◽  
Degree Day ◽  
Risk Of Predation ◽  
Influence Of Water ◽  
Developmental Rates ◽  
Developmental Phases

We sampled eggs and larvae of white sucker, Catostomus commersoni, on six spawning grounds to (i) determine the influence of water temperature and discharge on spawning and (ii) assess the reliability of four degree-day equations developed to predict the attainment of organogenesis, eyed egg, hatching, and swim-up phases. We estimated a threshold temperature for spawning of 13°C at four sites and 10°C at two colder sites. A delay of 2 or 3 days was observed between the threshold and the onset of spawning. On average, the degree-day equations predicted the attainment of the developmental phases with an accuracy of 1.6 days, except at the two colder sites, where developmental rates were faster than predicted. The lower spawning temperatures and faster developmental rates observed at the colder sites were interpreted as adaptations to the reduced growing season. Finally, at one site the drift of swim-up larvae occurred over a 6-day period even though spawning lasted 24 days; it was not possible to determine the exact duration of drift at the other sites. This synchronization could be an adaptation lowering the risk of predation on individual larvae, as all the larvae enter the lake within a few days.

Developmental rates of the aphid Aphis pomi (Aphidoidea: Aphididae) and its parasitoid Aphidius ervi (Hymenoptera: Aphidiidae)

Biologia ◽  
2010 ◽  
Vol 65 (5) ◽  
Author(s):  
Radovan Malina ◽  
Ján Praslička ◽  
Janka Schlarmannová
Keyword(s):  
Developmental Rate ◽  
Aphidius Ervi ◽  
Degree Days ◽  
Developmental Threshold ◽  
Aphis Pomi ◽  
Developmental Rates

AbstractDevelopmental rates of the aphid Aphis pomi and its parasitoid Aphidius ervi were compared at four constant temperatures (15, 20, 25, 30°C). Aphis pomi required 159.07 degree-days (DD) above lover developmental threshold (LDT) of 0.3°C. Aphidius ervi required 229.73 DD above LDT of 5.98°C. Developmental rate of A. pomi is higher than the developmental rate of A. ervi at the same conditions

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