Laboratory studies on the larval biology of Simulium venustum Say (Diptera: Simuliidae)

1976 ◽  
Vol 54 (10) ◽  
pp. 1657-1663 ◽  
Author(s):  
Joseph E. Mokry
Keyword(s):  
Growth Rate ◽  
Growth Curves ◽  
Temperature Profiles ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Larval Biology ◽  
Temperature Growth ◽  
Complete Development ◽  
Blackfly Larvae ◽  
Pass Through

Larvae reared from field-collected eggs of Simulium venustum were found to pass through six larval instars. Temperature strongly affected both the growth rate of larvae and their survival. At 5, 10, and 12 °C all S. venustum larvae died before reaching the sixth instar. At 15 °C, larvae were found to be able to complete development to the sixth instar, although only 10.5% survived to this stage. Increases in temperature led to increases in survival and rate of growth, with the best survival (20.4%) at 22 °C; most larvae required 22 days to reach this stage. Above 22 °C, survival decreased (5.7%), although the growth rate continued to increase. A growth model for blackfly larvae simulating natural conditions was constructed using temperature–growth curves obtained in laboratory trials and comparing these data with stream temperature profiles.

Probiotics Slow the Growth of Pathogenic Bacteria

2019 ◽  
Vol 14 (1) ◽  
pp. 28-31 ◽  
Author(s):  
Rowles H. L.
Keyword(s):  
Growth Rate ◽  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Diarrheal Disease ◽  
Growth Curves ◽  
Mortality Rates ◽  
Controlled Delivery ◽  
E Coli ◽  
Multiple Strains ◽  
Commercial Probiotics

Probiotics are live microorganisms, which when ingested in sufficient amounts, confer health benefits to the host by improving the gut microflora balance. The purpose of this research was to determine whether commercial probiotic products containing multitude of commensal bacteria would reduce the growth rate of pathogenic bacteria, specifically Escherichia coli and Salmonella typhimurium. Growth curves were established, and the growth rates were compared for samples of E. coli, S. typhimurium, Nature’s Bounty Controlled Delivery probiotic, Sundown Naturals Probiotic Balance probiotic, and cocultures of the pathogenic bacteria mixed with the probiotics. The findings of this research were that the commercial probiotics significantly reduced the growth rate of E. coli and S. typhimurium when combined in cocultures. Probiotics containing multiple strains may be taken prophylactically to reduce the risk of bacterial infections caused by E. coli and S. typhimurium. Probiotics could be used to reduce the high global morbidity and mortality rates of diarrheal disease.

scholarly journals Chasing the ghost of infection past: identifying thresholds of change during the COVID-19 infection in Spain

2020 ◽  
Vol 148 ◽  
Author(s):  
Luis Santamaría ◽  
Joaquín Hortal
Keyword(s):  
Public Health ◽  
Growth Rate ◽  
Health Communication ◽  
Communication Strategies ◽  
Growth Curves ◽  
Personal Hygiene ◽  
Exponential Growth Rate ◽  
Public Health Communication ◽  
Containment Measures ◽  
Key Events

Abstract One of the largest nationwide bursts of the first COVID-19 outbreak occurred in Spain, where infection expanded in densely populated areas through March 2020. We analyse the cumulative growth curves of reported cases and deaths in all Spain and two highly populated regions, Madrid and Catalonia, identifying changes and sudden shifts in their exponential growth rate through segmented Poisson regressions. We associate these breakpoints with a timeline of key events and containment measures, and data on policy stringency and citizen mobility. Results were largely consistent for infections and deaths in all territories, showing four major shifts involving 19–71% reductions in growth rates originating from infections before 3 March and on 5–8, 10–12 and 14–18 March, but no identifiable effect of the strengthened lockdown of 29–30 March. Changes in stringency and mobility were only associated to the latter two shifts, evidencing an early deceleration in COVID-19 spread associated to personal hygiene and social distancing recommendations, followed by a stronger decrease when lockdown was enforced, leading to the contention of the outbreak by mid-April. This highlights the importance of combining public health communication strategies and hard confinement measures to contain epidemics.

scholarly journals The differential transmissibility of myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale)

1975 ◽  
Vol 75 (2) ◽  
pp. 237-247 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan
Keyword(s):  
Host Resistance ◽  
Oryctolagus Cuniculus ◽  
Selective Advantage ◽  
Myxoma Virus ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Male And Female ◽  
The Mean ◽  
Virus Strains ◽  
Sampling Times

SUMMARYLaboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

A note on growth curves of rabbit lines selected on growth rate or litter size

1993 ◽  
Vol 57 (2) ◽  
pp. 332-334 ◽  
Author(s):  
A. Blasco ◽  
E. Gómez
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Growth Curves ◽  
Live Weight ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Standard Errors ◽  
Adult Weight ◽  
Weight Growth ◽  
Using Data

Two synthetic lines of rabbits were used in the experiment. Line V, selected on litter size, and line R, selected on growth rate. Ninety-six animals were randomly collected from 48 litters, taking a male and a female each time. Richards and Gompertz growth curves were fitted. Sexual dimorphism appeared in the line V but not in the R. Values for b and k were similar in all curves. Maximum growth rate took place in weeks 7 to 8. A break due to weaning could be observed in weeks 4 to 5. Although there is a remarkable similarity of the values of all the parameters using data from the first 20 weeks only, the higher standard errors on adult weight would make 30 weeks the preferable time to take data for live-weight growth curves.

High temperature growth rate in MOCVD growth of AlGaAs

1984 ◽  
Vol 68 (1) ◽  
pp. 169-175 ◽  
Author(s):  
Tetsuo Soga ◽  
Yasuhito Takahashi ◽  
Shiro Sakai ◽  
Masayoshi Umeno
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Temperature Growth ◽  
Mocvd Growth

Decomposition of Growth Curves into Growth Rate and Acceleration: a Novel Procedure to Monitor Bacterial Growth and the Time-Dependent Effect of Antimicrobials

2021 ◽  
Author(s):  
M. Luisa Navarro-Pérez ◽  
M. Coronada Fernández-Calderón ◽  
Virginia Vadillo-Rodríguez
Keyword(s):  
Growth Rate ◽  
Mathematical Models ◽  
Bacterial Growth ◽  
Time Course ◽  
Antimicrobial Agents ◽  
Numerical Procedure ◽  
Growth Curves ◽  
Predictive Microbiology ◽  
Insight Into ◽  
Over Time

In this paper, a simple numerical procedure is presented to monitor the growth of Streptococcus sanguinis over time in the absence and presence of propolis, a natural antimicrobial. In particular, it is shown that the real-time decomposition of growth curves obtained through optical density measurements into growth rate and acceleration can be a powerful tool to precisely assess a large range of key parameters [ i.e. lag time ( t 0 ), starting growth rate ( γ 0 ), initial acceleration of the growth ( a 0 ), maximum growth rate ( γ max ), maximum acceleration ( a max ) and deceleration ( a min ) of the growth and the total number of cells at the beginning of the saturation phase ( N s )] that can be readily used to fully describe growth over time. Consequently, the procedure presented provides precise data of the time course of the different growth phases and features, which is expected to be relevant, for instance, to thoroughly evaluate the effect of new antimicrobial agents. It further provides insight into predictive microbiology, likely having important implications to assumptions adopted in mathematical models to predict the progress of bacterial growth. Importance: The new and simple numerical procedure presented in this paper to analyze bacterial growth will possibly allow identifying true differences in efficacy among antimicrobial drugs for their applications in human health, food security, and environment, among others. It further provides insight into predictive microbiology, likely helping in the development of proper mathematical models to predict the course of bacterial growth under diverse circumstances.

scholarly journals Growth curve of Atlantoscia floridana (van Name) (Crustacea, Isopoda, Philosciidae) from a Brazilian Restinga Forest

2004 ◽  
Vol 21 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Paula Beatriz Araujo ◽  
Georgina Bond-Buckup
Keyword(s):  
Growth Rate ◽  
Growth Curve ◽  
Urban Areas ◽  
Field Data ◽  
Growth Curves ◽  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Differential Growth ◽  
Estimate Life Expectancy ◽  
Males And Females

The terrestrial isopod Atlantoscia floridana (van Name, 1940) occurs from the U.S.A. (Florida) to Brazil and Argentina. In the southernmost Brazilian State, Rio Grande do Sul, the species is recorded in many localities, in urban and in non-urban areas. The growth curve of Atlantoscia floridana based on field data is presented. The specimens were sampled from April, 2000 to October, 2001 at the Reserva Biológica do Lami (RBL), Rio Grande do Sul. Captured individuals were sexed and had their cephalothorax width measured, with the data analyzed with von Bertalanffy's model. The growth curves for males and females are described, respectively, by the equations: Wt = 1.303 [1 - e-0.00941 (t + 50.37)] and Wt = 1.682 [1 - e-0.00575 (t + 59.13)]. The curves showed differential growth between sexes, where females reach a higher Wµ with a slower growth rate. Based on the growth curves it was also possible to estimate life expectancy for males and females.

Temperature-Growth Relations and Genetic Diversity of A2 Mating-Type Isolates of Phytophthora cinnamomi in Australia

1974 ◽  
Vol 22 (2) ◽  
pp. 231 ◽  
Author(s):  
CJ Shepherd ◽  
BH Pratt
Keyword(s):  
Growth Rate ◽  
First Generation ◽  
Phytophthora Cinnamomi ◽  
Phytophthora Species ◽  
Temperature Growth ◽  
Field Isolates ◽  
Place Of Origin ◽  
Successive Generations ◽  
Cardinal Temperatures ◽  
Range Of Values

Determinations of cardinal temperatures for growth on various media of 50 Australian isolates of Phytophthova cinnamomi showed that growth did not occur outside the range 5-35°C. The range of temperatures at which growth optima occurred varied according to the isolate and medium used and encompassed the whole range of values reported by overseas authors. Growth rates of 361 isolates on corn meal agar at 25°C varied within the range 4.7-10.5 mm/day. There was no correlation between optimum temperature and whether isolates were slow- or fastgrowing or their place of origin. Fast-growing isolates (6-11 mm/day) were obtained from all States, but slower-growing isolates (<6 mm/day) were obtained only from southern and western regions of Australia. Populations from different regions of Australia exhibited different growth rate parameters. The variability of mycelial isolates in culture was studied by examining differences in growth rate among replicated parent, single-zoospore, single-zoosporangium and single terminal-hyphal isolates. Extensive variation was found among first generation single-zoospore progenies of field isolates, with lesser variation among progeny of single zoosporangia, terminal hyphal cultures and second and third generation zoospore derivatives. The origin of this variation is discussed and it is suggested that field isolates are heterokaryotic, since zoospores proved to be predominantly uninucleate. When various Phytophthora species were incubated at temperatures above those at which growth was possible and then returned to 25°C, their subsequent ability to resume growth depended on the particular time-temperature combination used. Considerable variation of response was found among a number of isolates of P. cinnamomi and, following the establishment of single zoospore isolates, the potential variability of field isolates was shown to persist through successive generations of zoospore propagation. It is suggested that a cytoplasmic mechanism of inheritance may be responsible for this variation.

The Effect of Temperature on the Growth and Respiration of Fish Embryos (Salmo Fario)

1932 ◽  
Vol 9 (3) ◽  
pp. 271-276
Author(s):  
A. H. WOOD
Keyword(s):  
Growth Rate ◽  
Oxygen Consumption ◽  
Relative Intensity ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Effect Of Temperature ◽  
Total Oxygen ◽  
Average Efficiency ◽  
Complete Development ◽  
Time Required

1. The rate of respiration (as expressed in c.c. O2 per gram embryo per hour) of the embryos of Salmo fario remains constant at any given temperature until the embryo has reached its maximum growth-rate, after this point it declines. It is suggested that the rate of respiration may be proportional to the amount of available yolk. 2. When incubated at 7° C. the time required to complete development after hatching was 58 days and the total oxygen consumed by an average embryo during this period was 20·31 c.c. (N.T.P.). At 12° the time required for the completion of development was reduced to 27 days, but the oxygen consumption remained practically unchanged at 20·71 c.c. At 3° C. the time required for development was 108 days and the oxygen consumption was 26·96 c.c. per embryo. 3. At 7 and 12° C. the efficiency of development was found to be identical with the value given by Gray for 11·5° C., viz. 63 per cent.; at 3°C. the average efficiency over the period considered was only 54 per cent. 4. It is suggested that, between the limits of temperature to which a trout egg is normally exposed, the effect of temperature on respiration is neither greater nor less than its effect on the growth-rate; possibly both processes are dependent on the same controlling factor. Above and below this range of temperature, the relative intensity of the respiratory processes (to those of growth) is increased, and a smaller embryo is the final result of incubation.

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