scholarly journals Comparative biology of two populations of Lutzomyia umbratilis (Diptera: Psychodidae) of Central Amazonia, Brazil, under laboratory conditions

2004 ◽  
Vol 64 (2) ◽  
pp. 227-235 ◽  
Author(s):  
S. C. B. Justiniano ◽  
A. C. Chagas ◽  
F. A. C. Pessoa ◽  
R. G. Queiroz
Keyword(s):  
Life Cycle ◽  
Cuticular Hydrocarbon ◽  
River System ◽  
Sand Fly ◽  
Amazon River ◽  
Adult Longevity ◽  
Isolated Populations ◽  
Rio Negro ◽  
Two Populations ◽  
Leishmania Guyanensis

Lutzomyia umbratilis is the main vector of cutaneous leishmaniasis due to Leishmania guyanensis in northern South America. It has been found naturally infected with this species of Leishmania only east of the Rio Negro and north of the Rio Amazonas. However, populations of this sand fly species are also present in areas south of the Amazon river system, which may act as a geographical barrier to the Leishmania guyanensis cycle. With the aim of looking for possible biological differences between populations of L. umbratilis from each side of this river system, their biology in the laboratory was investigated. Progenitors collected on tree bases in Manaus and Manacapuru (east and west, respectively, of the Rio Negro) were reared in the laboratory. Results from observations of the life cycle, fecundity, fertility, and adult longevity at 27ºC and 92% RH were analyzed by descriptive statistics and z, t, U, and chi2 tests. Although the Manaus and Manacapuru colonies showed a longer developmental time than most Lutzomyia species reared at similar temperatures, length of time of egg and 4th instar larva of the two populations differed significantly (p < 0.01). Females of the latter retained significantly (p < 0.001) less mature oocytes, and the general productivity (% adults from a known number of eggs) of the colony was significantly (p < 0.01) higher than that of the former. These results show that the L. umbratilis population of Manaus is more productive, and thus a better candidate for future mass-rearing attempts. The two populations differ in their life cycle, fecundity, fertility, adult longevity, and emergence. These differences may reflect some divergence of intrinsic biological features evolved as a result of their geographical isolation by the Rio Negro. It is expected that further investigations on morphometry, cuticular hydrocarbon, isoenzyme, molecular and chromossomal analyses, infection, and cross-mating experiments with these and other allopatric populations of both margins of the Amazon river system will help reveal whether or not L. umbratilis has genetically diverged into two or more reproductively isolated populations of vectors or non-vectors of Leishmania guyanensis.

Community of parasites inTriportheus curtusandTriportheus angulatus(Characidae) from a tributary of the Amazon River system (Brazil)

2016 ◽  
Vol 51 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Marcos Sidney Brito Oliveira ◽  
Raissa Alves Gonçalves ◽  
Marcos Tavares-Dias
Keyword(s):  
River System ◽  
Amazon River

Developmental gene expression in Leishmania donovani: differential cloning and analysis of an amastigote-stage-specific gene

1994 ◽  
Vol 14 (5) ◽  
pp. 2975-2984
Author(s):  
H Charest ◽  
G Matlashewski
Keyword(s):  
Life Cycle ◽  
Leishmania Donovani ◽  
Repetitive Sequences ◽  
Protozoan Parasite ◽  
Life Cycle Stage ◽  
Immune Serum ◽  
Sand Fly ◽  
Specific Gene ◽  
Reading Frame ◽  
Developmental Gene Expression

Leishmania protozoans are the causative agents of leishmaniasis, a major parasitic disease in humans. During their life cycle, Leishmania protozoans exist as flagellated promastigotes in the sand fly vector and as nonmotile amastigotes in the mammalian hosts. The promastigote-to-amastigote transformation occurs in the phagolysosomal compartment of the macrophage cell and is a critical step for the establishment of the infection. To study this cytodifferentiation process, we differentially screened an amastigote cDNA library with life cycle stage-specific cDNA probes and isolated seven cDNAs representing amastigote-specific transcripts. Five of these were closely related (A2 series) and recognized, by Northern (RNA) blot analyses, a 3.5-kb transcript in amastigotes and in amastigote-infected macrophages. Expression of the amastigote-specific A2 gene was induced in promastigotes when they were transferred from culture medium at 26 degrees C and pH 7.4 to medium at 37 degrees C and pH 4.5, conditions which mimic the macrophage phagolysosomal environment. A2 genes are clustered in tandem arrays, and a 6-kb fragment corresponding to a unit of the cluster was cloned and partially sequenced. An open reading frame found within the A2-transcribed region potentially encoded a 22-kDa protein containing repetitive sequences. The recombinant A2 protein produced in Escherichia coli cells was specifically recognized by immune serum from a patient with visceral leishmaniasis. The A2 protein repetitive element has strong homology with an S antigen of Plasmodium falciparum, the protozoan parasite responsible for malaria. Both the A2 protein of Leishmania donovani and the S antigen of P. falciparum are stage specific and developmentally expressed in mammalian hosts.

Organic Carbon-14 in the Amazon River System

Science ◽  
1986 ◽  
Vol 231 (4742) ◽  
pp. 1129-1131 ◽  
Author(s):  
J. I. HEDGES ◽  
J. R. ERTEL ◽  
P. D. QUAY ◽  
P. M. GROOTES ◽  
J. E. RICHEY ◽  
...  
Keyword(s):  
Organic Carbon ◽  
River System ◽  
Amazon River ◽  
Carbon 14

LIFE HISTORY PARAMETERS IN MELANOPLUS SANGUINIPES (F.) IN TWO CRESTED WHEATGRASS PASTURES

1988 ◽  
Vol 120 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Norma E. Sanchez ◽  
Jerome A. Onsager
Keyword(s):  
Life History ◽  
Survival Rates ◽  
Adult Longevity ◽  
Melanoplus Sanguinipes ◽  
Crested Wheatgrass ◽  
Life History Parameters ◽  
Preoviposition Period ◽  
Point Estimates ◽  
Two Populations ◽  
Net Replacement

AbstractA combination of published techniques provided point estimates of life history parameters for two natural field populations of Melanoplus sanguinipes (F.) in crested wheatgrass pastures. Stage-specific survival rates averaged 0.4798, 0.2261, 0.7628, and 0.6903 for egg, instars I–III combined, instar IV, and instar V, respectively. Daily survival rates of adults averaged 0.9702, but were slightly lower for females than for males. Estimated duration of nymphal instars averaged 8.4 days, the adult preoviposition period averaged 13.3 days, and adult longevity averaged 26.7 and 36.3 days in the two populations. Oviposition rates were estimated for up to four successive ovipositions, and net replacement rates of populations also were estimated. Neither population replaced itself, indicating that potential capacities for increase were not approached under conditions of these studies.

Radium and barium in the Amazon River system

1984 ◽  
Vol 89 (C2) ◽  
pp. 2061 ◽  
Author(s):  
Willard S. Moore ◽  
John M. Edmond
Keyword(s):  
River System ◽  
Amazon River

Aquatic ecosystems in Miocene western Amazonia – marine ingressions vs. salt leaching

2020 ◽  
Author(s):  
Werner Piller ◽  
Martin Gross
Keyword(s):  
Aquatic Ecosystems ◽  
Groundwater Discharge ◽  
River System ◽  
Salinity Range ◽  
Amazon River ◽  
Freshwater Environment ◽  
Salt Leaching ◽  
Saline Waters ◽  
North Western ◽  
Stable Isotope Enrichment

&lt;p&gt;Before the onset of the modern Amazon river system, north-western South America was shaped by an extensive wetland during the Miocene. This &amp;#8216;Pebas mega-wetland&amp;#8217; kept a well renowned endemic mollusk and ostracod fauna, which initiated a persisting debate about marine ingressions reaching the center of Amazonia at that time. Due to high endemism, uniformitarian principles are hardly applicable to this biota but also other paleontological, sedimentological and geochemical information led to ambiguous paleoenvironmental interpretations. These results are based on ostracod and foraminiferal assemblages and the oxygen and carbon stable isotopy of their biogenic calcite from an outcrop at the cutbank of the Amazon river (NE-Peru, ~55 km S of Iquitos). While ostracods (e.g., &lt;em&gt;Cyprideis&lt;/em&gt;) are able to calcify their carapaces along the entire salinity range, at least low saline conditions are a prerequisite for the biomineralization of calcareous foraminiferan tests. Hence, the finding of calcareous foraminifers (&lt;em&gt;Ammonia&lt;/em&gt;, &lt;em&gt;Elphidium&lt;/em&gt;), associated mainly with brackish water ostracods, indicates the presence of saline waters. In contrast, &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O- and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C-analyses performed on co-occurring ostracod valves and foraminiferan tests yielded constantly very light ratios. Such values refer to a pure freshwater environment and are incompatible with the interference of isotopically heavier, marine waters or an evaporative stable isotope enrichment. Based on these opposing data, we hypothesize that the Pebas mega-wetland was episodically influenced by mineralized but isotopically light groundwater discharge. Possibly, the resulting specific hydrochemistry contributed not only to the evolution of the endemic Pebasian fauna but also facilitated the sporadic settlement of euryhaline foraminifers, which mimics short-lived marine incursions.&lt;/p&gt;

Life History of Two Isolated Populations of Arctic Char (Salvelinus alpinus) in Spring-Fed Tributaries of the Canning River, Alaska

1973 ◽  
Vol 30 (8) ◽  
pp. 1215-1220 ◽  
Author(s):  
P. McCart ◽  
P. Craig
Keyword(s):  
Growth Rates ◽  
Bering Sea ◽  
Salvelinus Alpinus ◽  
Arctic Char ◽  
Isolated Populations ◽  
Meristic Characters ◽  
History Of ◽  
Western Arctic ◽  
Mature Fish ◽  
Two Populations

Two isolated populations of Arctic char (Salvelinus alpinus) in spring-fed tributaries of the Canning River, Alaska, had meristic characters that corresponded to those of the Western Arctic–Bering Sea form of Arctic char. The two populations demonstrated slight differences in growth rates, age at maturity, longevity, and food habits. The fish were characterized by small size (maximum 235 mm), low growth rates, low fecundities (maximum 199 eggs), and annual spawning after maturity. Mature fish were darkly pigmented and parr marks were retained throughout life. The spawning season appeared to be sometime in November, when the eggs of mature females averaged 3.8 mm in diameter.

scholarly journals ADULT LONGEVITY AND GROWTH TAKEOFF

2014 ◽  
Vol 20 (1) ◽  
pp. 165-188 ◽  
Author(s):  
Daishin Yasui
Keyword(s):  
Life Cycle ◽  
Life Expectancy ◽  
Early Retirement ◽  
Overlapping Generations ◽  
Working Life ◽  
Adult Longevity ◽  
Overlapping Generations Model ◽  
Fertility Decisions ◽  
Retirement Decisions ◽  
Positive Effect

This paper develops an overlapping-generations model in which agents make educational and fertility decisions under life-cycle considerations and retirement from work is distinguished from death. Gains in adult longevity induce agents to decrease fertility, invest in education, and achieve higher income in order to save more for retirement. Even if working life is shortened by early retirement, this mechanism works as long as adult longevity increases sufficiently. Our model can explain the positive effect of life expectancy on education without contradicting the fact that working life length has not substantially increased, because of retirement. We also provide new insights into the interaction between fertility and retirement decisions.

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