“Parthenogenesis” in Schistosoma mattheei

1969 ◽  
Vol 43 (1-2) ◽  
pp. 197-206 ◽  
Author(s):  
M. G. Taylor ◽  
M. B. A. Amin ◽  
G. S. Nelson
Keyword(s):  
Reproductive Isolation ◽  
Experimental Studies ◽  
Biological Significance ◽  
Considerable Proportion ◽  
Mixed Infections ◽  
Transmission Potential ◽  
Single Sex ◽  
Large Numbers ◽  
Rectal Biopsies ◽  
Full Maturity

Experimental studies in mice have shown that with single sex female infections of S. mattheei there is a slow maturation of the worms with evidence of incomplete parthenogenesis; at 9 weeks no eggs were produced but at 17 weeks there was an average of 500 eggs per mouse. These were all non viable. Under similar conditions S. mansoni females failed to produce eggs.When the females of S. mattheei were paired with males of S. mansoni, the females reached full maturity and produced large numbers of eggs typical of their own species-many of the eggs were non viable but some contained active miracidia.It is considered that this is an example of parthenogenesis and not hybridisation. Cross specific pairings of schistosomes must occur frequently in man particularly with S. haematobium, S. mansoni and S. mattheei and this phenomenon could be of considerable clinical, epidemiological and biological significance. Parthenogenesis in mixed infections probably accounts for the large number of non-viable S. haematobium eggs seen in rectal biopsies, and it may also be important in reducing the transmission potential of schistosomes to man since cross pairing must result in the “sterilisation” of a considerable proportion of the female worms in mixed infections. This phenomenon may also explain the observed reproductive isolation of schistosome species which simultaneously infect the same host.

scholarly journals Design, fabrication and experimental studies of compliant flexure diaphragm for micro pump

2018 ◽  
Vol 7 (2.21) ◽  
pp. 66 ◽  
Author(s):  
R Roopa ◽  
P Navin Karanth ◽  
S M. Kulkarni
Keyword(s):  
Polyvinylidene Fluoride ◽  
High Performance ◽  
Experimental Studies ◽  
Single Layer ◽  
Operating Voltage ◽  
Driving Voltage ◽  
Element Analysis ◽  
Central Deflection ◽  
Large Numbers ◽  
Micro Pump

This study reports the performance of piezo actuated compliant flexure diaphragm for micropump and MEMS application. To achieve the high performance of diaphragm at the low operating voltage compliant flexure diaphragm design is introduced. Very limited work has done on the diaphragms of micropump. Large numbers of mechanical micropumps have used plane diaphragms. The central deflection of diaphragm plays an important role in defining the micropump performance. The flow rate of mechanical type micropump strongly depends on the central deflection of diaphragm. In this paper compliant flexure diaphragms are designed for micropump to achieve higher deflection at lower operating voltage. Finite element analysis of compliant flexure diaphragm with single layer PVDF (Polyvinylidene fluoride) actuator is simulated in COMSOL. Compliant flexure diaphragms with a different number of flexures are analyzed. The central deflection of compliant flexure diaphragms is measured for driving voltages of 90V to 140V in 10 steps. The deflection of the compliant flexure diaphragm mainly depends on flexure width and length, the number of flexures in the diaphragm, PVDF thickness, diaphragm thickness and driving voltage. Use of compliant flexure diaphragm for micropump will reduce the mass and driving voltage of micropump. An attempt is made to compare the results of compliant flexure diaphragms with plane diaphragms. From the experimental results it is noticed that the compliant flexure diaphragm deflection is twice that of the plane diaphragm at same driving voltage. Deflection of three flexure and four flexure compliant diaphragms is 10.5µm and 11.5µm respectively at 140V.  

scholarly journals The Geometric Framework for Nutrition: New Insights Into How What We Eat Affects How We Age

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 845-845
Author(s):  
Alan Cohen ◽  
David Raubenheimer
Keyword(s):  
Human Health ◽  
Caloric Restriction ◽  
Brain Aging ◽  
Experimental Studies ◽  
Geometric Framework ◽  
Complex Interactions ◽  
Large Numbers ◽  
In The Wild ◽  
Nutritional Needs ◽  
Biology Of Aging

Abstract The geometric framework for nutrition (GFN) is an approach to understanding the effect of nutrition considering multiple nutrients simultaneously. Originally developed in experimental studies of insects to model how nutritional needs evolve depending on ecological context, and since extended to many taxa including non-human primates in the wild, the technique is increasingly applied to understand human health and aging. Here, we invite four varied talks showcasing the flexibility and potential of this approach from the basic biology of aging to observational human studies and clinical trials. D. Raubenheimer will give an overview of the method, its history, and its applications in aging and human health. D. Wahl will present results showing how GFN can help develop diets that recapitulate caloric restriction and its effects on brain aging. S. Das will show how GFN can be used to improve the feasibility of caloric restriction in humans without compromising its effects. Finally, A. Cohen will present results showing how GFN can be deployed in an epidemiological context and used to characterize complex interactions among large numbers of nutrients in determining health. Together, these results show that a simplistic conception of nutrition as calories is far from sufficient to understand its effects on health and aging. Evolution has shaped the nutritional needs of each species for its environment, with appropriate levels of flexibility. GFN provides an approach to capture the relevant nuance, with the results presented at this symposium but scratching the surface. Nutrition Interest Group Sponsored Symposium.

Experimental Studies on the Biology of Capillaria obsignata Madsen, 1945, a Nematode Parasite of the Domestic Fowl

1965 ◽  
Vol 39 (4) ◽  
pp. 399-412 ◽  
Author(s):  
D. Wakelin
Keyword(s):  
Domestic Fowl ◽  
Experimental Studies ◽  
Ultra Violet ◽  
Food Conversion ◽  
Ultra Violet Radiation ◽  
Large Numbers ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Violet Radiation

The life history and biology of C. obsignata in the domestic fowl is described and discussed, together with aspects of the host-parasite relationship. The development of the eggs is shown to be influenced by temperature, humidity, ultra violet radiation and other environmental conditions and these are related to the epidemiology of the parasite. The fowl is susceptible to the development of large numbers of worms, but shows some reaction to very large infective doses. The numbers of worms developing in the host are influenced by the size of the infection and by the age of the host. Large infections produce a consistent depression in weight gain and reduce the efficiency of food conversion. Pathological changes arising from experimental infections are described and compared with those observed in natural infections.

scholarly journals CCR6–CCL20 Axis in IBD: What Have We Learnt in the Last 20 Years?

2018 ◽  
Vol 1 (1) ◽  
pp. 57-74 ◽  
Author(s):  
Ranmali Ranasinghe ◽  
Rajaraman Eri
Keyword(s):  
Intestinal Inflammation ◽  
Experimental Studies ◽  
Protective Mechanisms ◽  
Cc Chemokine ◽  
Large Numbers ◽  
Causative Factors ◽  
Chemokine Ligand ◽  
Disease Entities ◽  
Inflammatory Bowel ◽  
The Subject

CC chemokine receptor 6 (CCR6) and its specific partner CC chemokine ligand 20 (CCL20) are known to play a pivotal role in intestinal inflammation. CCR6-associated inflammatory bowel disease (IBD) is already at the forefront of experimental inflammatory disease models, being the subject of numerous analytical studies. IBD is associated with two sub phenotypes, Crohn’s disease (CD) and ulcerative colitis (UC). Both these disease entities produce potent immune dysregulation followed by intense tissue damage within the gut mucosal system, initiating symptoms that are severely debilitating. Multiple causative factors are said to be responsible for IBD, but direct immune dysfunction is kindled by overplay of innate and adaptive immune responses produced against the luminal contents through the weakened or leaky gut epithelial barrier. Once immune homeostasis is not achieved by endogenous protective mechanisms, the self-assertive adaptive immunity mobilizes its various T and B cell cohorts, initializing their immune mechanisms by deploying the immune cells towards the site of infection. CCR6 and its unique solitary ligand CCL20 are small protein molecules that are abundantly expressed by T and B lymphocytes and act as chemotactic immune-modulatory envoys that help in the deployment of the effector lymphocyte arm of the immune system and produce two directly opposing outcomes in IBD. This dichotomous immunity consists of either immune tolerance or inflammation which then develops into a chronic state, remaining unresponsive to inherent immunity or targeted clinical therapy. In this review, we have identified large numbers of experimental studies that have employed both mouse models and clinical subjects spanning a period of nearly two decades and we have clustered these into 13 different groups. This review will provide greater understanding of the CCR6–CCL20 axis in IBD and identify gaps in the literature that can be filled in the future.

Rewriting Title IX: The Department of Education's Response to Feminists' Comments in the Rulemaking Process

2016 ◽  
Vol 12 (03) ◽  
pp. 491-517 ◽  
Author(s):  
Ashley English
Keyword(s):  
Sex Education ◽  
Title Ix ◽  
Department Of Education ◽  
High Quality ◽  
Advocacy Organizations ◽  
Policy Makers ◽  
Feminist Organizations ◽  
Single Sex ◽  
Large Numbers ◽  
First Time

Feminist organizations, like many other interest groups and advocacy organizations, have increasingly turned to the rulemaking process to create meaningful policy change. Although rulemaking is an attractive policy-making venue for feminists because it provides them with an opportunity to bypass congressional gridlock and interact with more women policy makers than they might in Congress, the existing literature does not address how and when feminist organizations' participation in rulemaking is influential. To examine this question for the first time, I analyze a sample of the 5,860 comments that the U.S. Department of Education received in response to its 2004 proposed rule allowing for public single-sex education programs and the department's justifications for its proposed and final rules. Specifically, I ask whether findings from the rulemaking literature showing that organizations can encourage bureaucrats to change their proposed rules when they submit large numbers of high-quality, homogenous, opposing comments hold for feminist organizations in a redistributive policy area. The findings indicate that when bureaucrats receive multiple sets of high-quality homogenous comments, they are more likely to side with commenters who support their initial proposals and/or partisan and ideological positions.

Functional Morphology of the Mucosa of the Middle Ear and Eustachian Tube

1976 ◽  
Vol 85 (2_suppl) ◽  
pp. 36-43 ◽  
Author(s):  
David J. Lim
Keyword(s):  
Eustachian Tube ◽  
Middle Ear ◽  
Surface Active Agent ◽  
Active Agent ◽  
Biological Significance ◽  
Normal Function ◽  
Middle Ear Mucosa ◽  
Defense Systems ◽  
Large Numbers ◽  
Surface Active

A review of available histological, histochemical and ultrastructural data on middle ear mucosa and the Eustachian tube was made to provide a broad cellular basis for understanding middle ear effusions. The presence of mucociliary defense system in a large part of the Eustachian tube and middle ear is seen as the first line of defense. Secretion by the mucosa has a profound biological significance. Immunoglobulins A, G, and even E and M are produced locally by the mucosa and may contribute to the immunodefense of the middle ear. Secretory lysozyme is also produced by the mucosa and may contribute enzymatic defense of the ear. Mucosal immunoglobulins and lysozyme are significantly elevated in the effusions, which would imply that local defense systems are hyperactive in OME. It also appears that these increases are related to the increase of the secretory cell population. It is also suspected that auditory surface-active agent is produced locally and may facilitate normal function of the tube. The middle ear also can transport macromolecules very rapidly across intact mucosal epithelium. The large numbers of tissue and wandering macrophages found in the mucosa and effusions would also imply that the middle ear is capable of efficient phagocytosis, which may be involved in processing antigen.

Gulls and Aircraft

1978 ◽  
Vol 5 (4) ◽  
pp. 277-280 ◽  
Author(s):  
Victor E. F. Solman
Keyword(s):  
Fast Moving ◽  
Insect Population ◽  
Considerable Proportion ◽  
Food Wastes ◽  
Jet Engines ◽  
Mouse Population ◽  
Early Autumn ◽  
Large Numbers

Birds, struck during flight by fast-moving modern aircraft or getting ingested in jet engines, cause numerous serious accidents of which some involve human deaths. Gulls of various species are the birds involved in a considerable proportion of these accidents due to bird-strikes.Gull-strikes of aircraft in flight may be expected:1. When there is a chronic attraction such as a concentrated worm or insect population, a high mouse population, or some other biological attractant;2. When there is lack of care in disposal of food-wastes;3. When drainage on an airfield or on flat-roofed buildings is not properly designed or is not functioning well; or4. During the early autumn when large numbers of inexperienced, immature gulls are in flight.

Schistosoma mansoni: changes in elemental composition in relation to the age and sexual status of the worms

Parasitology ◽  
1983 ◽  
Vol 86 (3) ◽  
pp. 439-453 ◽  
Author(s):  
M. K. Shaw ◽  
D. A. Erasmus
Keyword(s):  
Schistosoma Mansoni ◽  
Female Worm ◽  
Calcium Content ◽  
Mature Female ◽  
Mixed Infections ◽  
Male Worm ◽  
Male And Female ◽  
Single Sex ◽  
Significant Difference ◽  
First Time

SUMMARYChanges during development in the elemental contents (Ca, P, K, Mg and S) of male and femaleSchistosoma mansonifrom both mixed and single sex infections have been measured for the first time. In mixed infections, there is a significant difference between the calcium content of male and female worms; female worms having between 2 and 3 times more calcium. In mature female worms from mixed infections, after an initial rise in the calcium content corresponding to the time when vitelline development occurs, the amount of calcium ranged from 0.36 to 0.65 mg/g dry wt, whereas the amounts in similarly aged male worms ranged between 0.19 and 0.32 mg/g dry wt. While the type of infection does not affect the calcium content of male worms, a significant difference in the calcium levels in female worms from mixed and single sex infections was found. The amount of calcium in females from single sex infections ranged from 0.21 to 0.39 mg/g dry wt and this is considerably less than the levels recorded in females from mixed infections. This difference in calcium content between mixed and single sex infections can be related to the differences in degree of development of the vitelline gland in the two types of female worm. The amounts of phosphorus, potassium, magnesium and sulphur in both male and female worms from both single and mixed infections are similar, although females from mixed infections contained slightly more phosphorus than either females from single sex infections or either type of male worm.

Reproductive Isolation Between the Sunfish Lepomis gibbosus and L. macrochirus

1967 ◽  
Vol 24 (3) ◽  
pp. 495-514 ◽  
Author(s):  
Francis W. Clark ◽  
Miles H. A. Keenleyside
Keyword(s):  
Reproductive Isolation ◽  
Visual Recognition ◽  
Nest Site Selection ◽  
Lepomis Gibbosus ◽  
Major Barrier ◽  
Interspecific Differences ◽  
Large Numbers ◽  
Interspecific Courtship ◽  
Ethological Isolation ◽  
Breeding Seasons

Reproductive isolation appeared to be complete between pumpkinseeds (Lepomis gibbosus) and bluegills (L. macrochirus) when equal numbers (1:1 sex ratio) were stocked in each of two similar ponds near London, Ontario, and observed during the breeding seasons of 1964 and 1965. Ethological isolation, through visual recognition of potential conspecific mates, was probably the major barrier to hybridization. Interspecific courtship and attempted spawning were not seen; intraspecific courtship and spawning were frequently observed. No clearly identifiable hybrids were found among large numbers of yearling and 2-year-old offspring collected in both ponds in 1965 and 1966.Pumpkinseeds began nesting about 3 weeks before bluegills, but spawning by the two species broadly overlapped in time both years. Individual pumpkinseeds occupied nests for an average of 18.5 days; bluegills for 8.7 days. Duration of pumpkinseed nest occupancy appeared to vary directly with surface water temperature, whether eggs or fry were in the nests or not, whereas bluegills tended to remain on nests containing eggs or fry, regardless of temperature fluctuations. Bluegills nested in deeper water and further from shore than pumpkinseeds, and bluegills tended to nest in colonies whereas pumpkinseeds did not. Interspecific differences were not found in nest site selection with respect to substrate or vegetation.

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