Functional design of microvilli in the Malpighian tubules of the insect Rhodnius prolixus

1983 ◽  
Vol 60 (1) ◽  
pp. 117-135
Author(s):  
T.J. Bradley
Keyword(s):  
Plasma Membranes ◽  
Current Knowledge ◽  
Morphological Difference ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Free Standing ◽  
Narrow Channels ◽  
Morphological Specialization ◽  
Mitochondrial Volume ◽  
The Mean

The Malpighian tubules of Rhodnius prolixus are divided into two regions; the upper tubule, which is the site of isosmotic secretion and haemolymph filtration, and the lower tubule where water and KCl are resorbed. In the upper tubule the microvilli are arranged in clumps consisting of several hundred microvilli lying closely parallel. The microvillar plasma membranes do not touch but are held approximately equal to 16 nm apart along the full length of the microvilli. As a consequence, the extracellular space between the microvilli consists of long narrow channels. A morphometric analysis of extracellular, cytoplasmic, endoplasmic reticular and mitochondrial volume within the clumps was conducted. Using the secretion rate of the epithelium and the channel dimensions, it was calculated that the mean residence time for secreted fluid in the intermicrovillar spaces was approximately equal to 0.4s. In view of our current knowledge of the physiology and morphology of the upper tubule, it is argued: (1) that osmotically driven water passes principally through the cells, not the junctional spaces; and (2) that the microvillar clumps are a morphological specialization, which serves to maximize solute-water coupling in the upper tubule. The microvilli in the lower tubule are free-standing, with no pattern of clumping as in the upper tubule. The axopods are about twice as long as the microvilli (10-14 micron) and are found in all regions of the lower tubule. This is in agreement with the proposal that the motile axopods serve to propel uric acid crystals through the lower tubule. No morphological difference was found between the upper and lower halves of the lower tubule, although the two portions are known to be physiologically distinct.

Ultrastructural Characterization of Malpighian Tubules of Rhodnius prolixus During the Insect's Feeding Cycle and Under Hyperosmotic Shock

2020 ◽  
Vol 129 (2) ◽  
pp. 189
Author(s):  
Jacenir Reis dos Santos-Mallet ◽  
Simone Patrícia Carneiro Freitas ◽  
Maria Luiza Ribeiro de Oliveira ◽  
Alice Helena Ricardo-Silva ◽  
Aníbal Gil Lopes ◽  
...  
Keyword(s):  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Hyperosmotic Shock ◽  
Ultrastructural Characterization ◽  
Feeding Cycle

scholarly journals Manual Therapy in Cervical and Lumbar Radiculopathy: A Systematic Review of the Literature

2021 ◽  
Vol 18 (11) ◽  
pp. 6176
Author(s):  
Tomasz Kuligowski ◽  
Anna Skrzek ◽  
Błażej Cieślik
Keyword(s):  
Manual Therapy ◽  
Functional Outcomes ◽  
Web Of Science ◽  
Current Knowledge ◽  
Controlled Trial ◽  
Future Research ◽  
Lumbar Radiculopathy ◽  
Inclusion Criteria ◽  
Randomized Controlled ◽  
The Mean

The aim of this study was to describe and update current knowledge of manual therapy accuracy in treating cervical and lumbar radiculopathy, to identify the limitations in current studies, and to suggest areas for future research. The study was conducted according to PRISMA guidelines for systematic reviews. A comprehensive literature review was conducted using PubMed and Web of Science databases up to April 2020. The following inclusion criteria were used: (1) presence of radiculopathy; (2) treatment defined as manual therapy (i.e., traction, manipulation, mobilization); and (3) publication defined as a Randomized Controlled Trial. The electronic literature search resulted in 473 potentially relevant articles. Finally, 27 articles were accepted: 21 on cervical (CR) and 6 in lumbar radiculopathy (LR). The mean PEDro score for CR was 6.6 (SD 1.3), and for LR 6.7 (SD 1.6). Traction-oriented techniques are the most frequently chosen treatment form for CR and are efficient in reducing pain and improving functional outcomes. In LR, each of the included publications used a different form of manual therapy, which makes it challenging to summarize knowledge in this group. Of included publications, 93% were either of moderate or low quality, which indicates that quality improvement is necessary for this type of research.

Effects of the cyclopeptide mycotoxin destruxin A on the Malpighian tubules of Rhodnius prolixus (Stål)

Toxicon ◽  
2010 ◽  
Vol 55 (6) ◽  
pp. 1162-1170 ◽  
Author(s):  
Esau Ruiz-Sanchez ◽  
Ian Orchard ◽  
Angela B. Lange
Keyword(s):  
Rhodnius Prolixus ◽  
Malpighian Tubules

Topographical variations in the structure of the smooth septate junction

1979 ◽  
Vol 37 (1) ◽  
pp. 373-389
Author(s):  
H.B. Skaer ◽  
J.B. Harrison ◽  
W.M. Lee
Keyword(s):  
Musca Domestica ◽  
Functional Significance ◽  
Freeze Fracture ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Septate Junction ◽  
Lanthanum Hydroxide ◽  
Septate Junctions ◽  
Standard Fixation

Smooth septate junctions in the midgut of Musca domestica and in Malpighian tubules of both Musca and Rhodnius prolixus are described. Details of the structures revealed after standard fixation, fixation in the presence of the stain, lanthanum hydroxide, and after freeze-fracture are discussed in the light of models previously put forward to explain the interrelations of the images obtained by these different methods. The organization of the junction between cells of the midgut varies in the apical-to-basal axis. At the apical border the septa (or ridges in freeze-fracture replicas) are packed tightly and follow an undulating but strictly parallel course. This packing loosens towards the middle of the junction until, at its basal extremity, the septa (ridges in replicas) are widely separated and follow independent meandering courses. That these features are found both in lanthanum-infiltrated specimens and freeze-fracture replicas allows a correlation to be made between the septa and the freeze-fracture ridges. The functional significance of these smooth septate junctions is discussed.

Anti-diuresis in the blood-feeding insect Rhodnius prolixus Stål: the peptide CAP2b and cyclic GMP inhibit Malpighian tubule fluid secretion.

1997 ◽  
Vol 200 (17) ◽  
pp. 2363-2367 ◽  
Author(s):  
M C Quinlan ◽  
N J Tublitz ◽  
M J O'Donnell
Keyword(s):  
Cyclic Gmp ◽  
Physiological Role ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Blood Feeding ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Tubule Fluid ◽  
Secretion Rates

Rhodnius prolixus eliminates NaCl-rich urine at high rates following its infrequent but massive blood meals. This diuresis involves stimulation of Malpighian tubule fluid secretion by diuretic hormones released in response to distention of the abdomen during feeding. The precipitous decline in urine flow that occurs several hours after feeding has been thought until now to result from a decline in diuretic hormone release. We suggest here that insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP are part of a novel mechanism of anti-diuresis. Secretion rates of 5-hydroxytryptamine-stimulated Malpighian tubules are reduced by low doses of CAP2b or cyclic GMP. Maximal secretion rates are restored by exposing tubules to 1 mmol l-1 cyclic AMP. Levels of cyclic GMP in isolated tubules increase in response to CAP2b, consistent with a role for cyclic GMP as an intracellular second messenger. Levels of cyclic GMP in tubules also increase as urine output rates decline in vivo, suggesting a physiological role for this nucleotide in the termination of diuresis.

Hepatic Subcellular Storage of Beta-Carotene in Rats Following Diet Supplementation

1999 ◽  
Vol 69 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Bianchi-Santamaria ◽  
Stefanelli ◽  
Cembran ◽  
Gobbi ◽  
Peschiera ◽  
...  
Keyword(s):  
Liver Tissue ◽  
Plasma Membranes ◽  
Beta Carotene ◽  
Subcellular Fractions ◽  
Organ Distribution ◽  
Total Liver ◽  
Opposite Behavior ◽  
The Mean ◽  
White Fat ◽  
And Storage

Beta-carotene (BC) storage was measured in liver and its subcellular fractions (plasma membranes, mitochondria, microsomes and nuclei) of rats fed BC added to diet. The BC supplementation dose was about 350 mg/week/rat. After 15 weeks of this supplementation, rats were killed and their livers were immediately excised and processed to obtain total liver tissue and its subcellular fractions. Their BC contents were measured by HPLC as pmols/mg protein. Intact BC was found to be stored in all the above subcellular fractions, thus showing that BC is probably taken up by liver cell lipid moiety. Interestingly, the mean BC concentrations in plasma membranes and mitochondria were significantly higher than that in total liver tissue. Our data confirmed that rodents are a good animal model for the study of BC metabolism and its effects on several pathologies, and cancer prevention and treatment in humans in spite of the fact that rodents are classified as white-fat animals because of their poor BC absorption and storage in fat and blood plasma, whereas humans are classified as yellow-fat organisms because of their opposite behavior in BC uptake and organ distribution.

scholarly journals Surgical Outcomes of Pure-Fat Myringoplasty for Small Tympanic Membrane Perforations: A Retrospective Study and Summary of the Literature in the Last 10 Years

2021 ◽  
Vol 64 (10) ◽  
pp. 711-719
Author(s):  
Min Kyu Lee ◽  
Tae Min Kim ◽  
Sung Jin Lim ◽  
Dong Heun Park ◽  
Yoon Chan Rah ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Success Rate ◽  
Tympanic Membrane ◽  
Surgical Outcomes ◽  
Pure Tone ◽  
Current Knowledge ◽  
Tympanic Membrane Perforations ◽  
The Mean ◽  
Hearing Outcomes ◽  
Paired T Test

Background and Objectives Fat myringoplasty is a simple, fast, and effective procedure for repairing tympanic membrane (TM) perforations. The aim of this study is to evaluate the surgical outcomes of pure-fat myringoplasty for small TM perforations at our hospital and review the current knowledge regarding fat myringoplasty, with consideration of the effectiveness of additional substances used in the treatment of small TM perforations.Subjects and Method We retrospectively studied 41 patients who underwent pure-fat myringoplasty at our hospital from March 2008 through April 2019 and were followed up for at least 2 months thereafter.Results Of 41 patients, 16 were males and 25 were females, with the mean age of 48 (male, 9-75 years; female, 16-65 years). All perforations were classified as small perforations, ranging from 1% to 17% of the TM. The overall success rate was 92.7%, with the TMs of 3 patients (7.3%) failing to close. Air-bone gap (ABG) decreased in 19 out of 24 patients who underwent both preoperative and postoperative pure tone audiometric examinations. The mean ABG was 4.42 dB (n=24; paired-t test, p=0.001; 95% confidence interval, 1.77-7.07). The literature review revealed that TM closure success rate of over 80% was associated with pure-fat myringoplasty, while the TM closure success rate for fat myringoplasty with additional substances was 85% to 100%.Conclusion Our study revealed a high TM closure success rate and good hearing outcomes are associated with pure-fat myringoplasty. Pure-fat myringoplasty seems to be sufficient for repairing small TM perforations.

scholarly journals A Comprehensive Analysis on Abundance, Distribution, and Bionomics of Potential Malaria Vectors in Mannar District of Sri Lanka

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Nayana Gunathilaka ◽  
Menaka Hapugoda ◽  
Rajitha Wickremasinghe ◽  
Wimaladharma Abeyewickreme
Keyword(s):  
Waste Water ◽  
Sri Lanka ◽  
Current Knowledge ◽  
Breeding Habitat ◽  
Control Measures ◽  
Malaria Vectors ◽  
Detailed Knowledge ◽  
Lagoon Water ◽  
Breeding Habitats ◽  
The Mean

Background. A detailed knowledge of the distribution of the malaria vectors in Mannar district of Sri Lanka has not been studied after 1927. Past records indicated the presence of only seven species of anophelines, namely, An. culicifacies, An. subpictus, An. barbirostris, An. peditaeniatus, An. nigerrimus, An. Jamesii, and An. maculatus. There have been many changes in terms of distribution of Anopheles in the district over time. Methods. Entomological surveillance was conducted on a monthly basis, comprising indoor hand collection, window trap collection, cattle-baited net collection, cattle-baited hut collection, and larval survey from June 2010 to June 2012 in 12 study areas under three entomological sentinel sites. The relationship between seven abiotic variables of the breeding habitats was measured. Pearson’s correlation coefficients were used to determine the associations between climatic variables and anopheline densities. Results. A total of 74,181 mosquitoes belonging to 14 Anopheles species were recorded. An. subpictus was the most predominant species from all techniques representing 92% (n=68,268) of the total anopheline collection. However, Anopheles culicifacies was not recorded from any site during the study period. Larval surveys identified 12 breeding habitat categories including waste water collections, lagoon water collections, and drains which were not recorded as breeding habitats by previous studies. The mean dissolved oxygen level of waste water collections was 3.45±0.15 mg/l. The mean salinity and conductivity of lagoon water collections were 21105±1344 mg/l and 34734±1974 μs/cm, respectively. Conclusion. The present study provides the updated knowledge on anopheline distribution and vector bionomics. Therefore, documentation of the current knowledge would be useful for learners and health authorities to design appropriate vector control measures in the prevention of reintroduction of malaria.

Interleukin-1 alpha in human sweat is functionally active and derived from the eccrine sweat gland

1994 ◽  
Vol 266 (3) ◽  
pp. R950-R959 ◽  
Author(s):  
K. Sato ◽  
F. Sato
Keyword(s):  
Sweat Gland ◽  
Plasma Membranes ◽  
Sweat Rate ◽  
Interleukin 1 ◽  
Biologically Active ◽  
Sweat Test ◽  
Cultured Fibroblasts ◽  
Human Sweat ◽  
The Mean ◽  
Secretory Coil

We wished to establish the presence of interleukin-1 (IL-1) in human sweat (5) and clarify its origin and mechanism of secretion. IL-1 alpha concentration ([IL-1 alpha]) in clean sweat from the back increased with the sweat rate, plateauing at the maximal sweat rate ([IL-1 alpha]max). The mean [IL-1 alpha]max was 545 pg/ml (n = 17) for men and 1,324 pg/ml for women in back sweat. The mean [IL-1 alpha]max for axillary sweat in men was 1,568 (n = 6). Palmar sweat was 9.2 ng/ml (n = 5) for IL-1 alpha and 7.9 ng/ml for IL-1 beta. [IL-1 alpha]max decreased to one-third that of the first sweat test, when second sauna sweat tests were conducted after 2 h of continuous sweating on the same day. Western blot analysis of the purified sweat IL-1 alpha fraction revealed bands at 17, 29, and 33 kDa. Immunoreactive IL-1 alpha was localized mainly in the secretory coil lumen, intercellular canaliculi, cytoplasm, mitochondria, and near plasma membranes. Polymerase chain reaction revealed the presence of IL-1 alpha mRNA in the sweat gland and in cultured human eccrine secretory coil cells. Both sweat IL-1 alpha and human recombinant IL-1 alpha at 500 pg/ml strongly stimulated interleukin-6 and interleukin-8 production in cultured fibroblasts. We conclude that the IL-1 alpha-like immunoreactive substance in sweat is IL-1 alpha itself, is derived from the sweat gland, and is biologically active at concentrations normally present in fresh sweat.

Serotonin triggers cAMP and PKA-mediated intracellular calcium waves in Malpighian tubules of Rhodnius prolixus

2014 ◽  
Vol 307 (7) ◽  
pp. R828-R836 ◽  
Author(s):  
Paula Gioino ◽  
Brendan G. Murray ◽  
Juan P. Ianowski
Keyword(s):  
Second Messenger ◽  
Fluid Secretion ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Insect Vector ◽  
Excess Water ◽  
Intracellular Ca ◽  
Single Meal ◽  
Hematophagous Insect

Rhodnius prolixus is a hematophagous insect vector of Chagas disease capable of ingesting up to 10 times its unfed body weight in blood in a single meal. The excess water and ions ingested with the meal are expelled through a rapid postprandial diuresis driven by the Malpighian tubules. Diuresis is triggered by at least two diuretic hormones, a CRF-related peptide and serotonin, which were traditionally believed to trigger cAMP as an intracellular second messenger. Recently, calcium has been suggested to act as a second messenger in serotonin-stimulated Malpighian tubules. Thus, we tested the role of calcium in serotonin-stimulated Malpighian tubules from R. prolixus. Our results show that serotonin triggers cAMP-mediated intracellular Ca2+ waves that were blocked by incubation in Ca2+-free saline containing the cell membrane-permeant Ca2+ chelator BAPTA-AM, or the PKA blocker H-89. Treatment with 8-Br-cAMP triggered Ca2+ waves that were blocked by H-89 and BAPTA-AM. Analysis of the secreted fluid in BAPTA-AM-treated tubules showed a 75% reduction in fluid secretion rate with increased K+ concentration, reduced Na+ concentration. Taken together, the results indicate that serotonin triggers cAMP and PKA-mediated Ca2+ waves that are required for maximal ion transport rate.

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