The Physiology of Excretion in the Cotton Stainer, Dysdercus Fasciatus, Signoret

1966 ◽  
Vol 44 (3) ◽  
pp. 553-566
Author(s):  
M. J. BERRIDGE
Keyword(s):  
Osmotic Pressure ◽  
Urine Flow ◽  
Malpighian Tubules ◽  
Hormone Concentration ◽  
Serum Dilution ◽  
Wide Range ◽  
Tentative Hypothesis ◽  
Cotton Stainer ◽  
Urine Formation ◽  
Different Parts

1. The preparation of isolated Malpighian tubules is described. The rate of urine flow increases with increasing serum dilution, and vice versa. Urine is almost isotonic with haemolymph over a wide range of osmotic pressure. 2. Serum collected from 3-day-old insects promotes urine formation, whereas that from 6-day-old insects does not. 3. A factor which was extracted from the m.n.c. accelerates the rate of urine flow, from a normal value of 0·87 to 3·1 mm.3 x 10- 3/min. The osmotic pressure of the urine, however, remains unchanged. 4. The hormone concentration of different parts of the nervous system was assayed with these isolated tubules. Most activity occurs in the m.n.c., but some activity is present in extracts from the c.c. and the fused ganglionic mass in the mesothorax. 5. Malpighian tubules isolated from 6-day-old insects remain inactive, but after the addition of hormone they immediately begin to produce urine. 6. These observations have been incorporated into a tentative hypothesis on the control of excretion in Dysdercus.

Insect-Like Characteristics of the Malpighian Tubules of a Non-Insect: Fluid Secretion in the Centipede Uthobius Forficatus (Myriapoda: Chilopoda)

1991 ◽  
Vol 158 (1) ◽  
pp. 165-180
Author(s):  
ANGELA WENNING ◽  
U. T. E. GREISINGER ◽  
JACQUES P. PROUX
Keyword(s):  
Cyclic Amp ◽  
Flow Rate ◽  
Fluid Secretion ◽  
Urine Flow ◽  
Malpighian Tubules ◽  
Urine Flow Rate ◽  
Dibutyryl Cyclic Amp ◽  
Diuretic Hormone ◽  
Urine Formation ◽  
Lithobius Forficatus

Fluid secretion by isolated upper and lower portions of Malpighian tubules in the centipede Lithobius forficatus L. was studied. Ion requirements, cellular and transepithelial potentials, dependence on external osmolality and the effects of an insect diuretic factor and transport-active drugs were investigated. Unlike many insects, L. forficatus exhibited strongly Na+-dependent, K+-independent urine formation. However, as in many insects, upper and lower tubule portions from L. forficatus produced a K+-enriched, hypertonic fluid, and the transepithelial potential was positive with respect to the haemolymph. Furthermore, furosemide (5×10−4moll−1) reversibly inhibited urine formation. Ouabain, even at 10−3moll−1, had little effect on urine flow rate in upper tubules but inhibited secretion in lower tubules, albeit not completely. Locust diuretic hormone (at 10−7moll−1) enhanced fluid secretion in L. forficatus, but its action was not mimicked by dibutyryl cyclic AMP. The results suggest that some characteristics attributed exclusively to insects are common to non-insect arthropods.

Urine Formation by the Malpighian Tubules of Calliphora

1968 ◽  
Vol 48 (1) ◽  
pp. 159-174
Author(s):  
M. J. BERRIDGE
Keyword(s):  
Osmotic Pressure ◽  
Potassium Concentration ◽  
Malpighian Tubules ◽  
Apical Surface ◽  
Bathing Medium ◽  
Sodium Potassium ◽  
Basal Plasma ◽  
External Potassium ◽  
Potassium Secretion ◽  
Urine Formation

1. Rate of urine formation is very sensitive to potassium concentration. 2. Potassium is concentrated in the urine by a mechanism which is independent of other monovalent cations. Rubidium, caesium and sodium are also capable of maintaining a flow of urine. At low external potassium concentrations, sodium stimulates potassium secretion. 3. Rate of urine secretion is stimulated by low osmotic pressures; the osmotic pressure of urine was slightly hypertonic throughout the range of external osmotic pressure employed. Addition of sucrose depresses rate of urine secretion; the potassium concentration of the urine increased by 1 mM/l. for each 2 mM/l. of sucrose added to the bathing medium. 4. Urine formation is insensitive to sulphanilamide, acetazolamide, ouabain and a wide variation of pH. 5. These observations are discussed in relation to the hypothesis that potassium secretion takes place across both surfaces of the cell. The pump on the basal surface may be a coupled sodium-potassium pump, whereas that on the apical surface may be electrogenic. 6. Microvilli at the apical surface or channels formed by a complex infolding of the basal plasma membrane may represent structural devices by which standing osmotic gradients can be established during solute-linked water transport across the cells of Malpighian tubules.

scholarly journals Assessing evidence for adaptive evolution in two hearing-related genes important for high-frequency hearing in echolocating mammals

2021 ◽  
Author(s):  
Hui Wang ◽  
Hanbo Zhao ◽  
Yujia Chu ◽  
Jiang Feng ◽  
Keping Sun
Keyword(s):  
Adaptive Evolution ◽  
Hair Cells ◽  
High Frequency ◽  
Phylogenetic Trees ◽  
Outer Hair Cells ◽  
Functional Domain ◽  
Coding Region ◽  
Selective Pressures ◽  
Wide Range ◽  
Different Parts

Abstract High-frequency hearing is particularly important for echolocating bats and toothed whales. Previously, studies of the hearing-related genes Prestin, KCNQ4, and TMC1 documented that adaptive evolution of high-frequency hearing has taken place in echolocating bats and toothed whales. In this study, we present two additional candidate hearing-related genes, Shh and SK2, that may also have contributed to the evolution of echolocation in mammals. Shh is a member of the vertebrate Hedgehog gene family and is required in the specification of the mammalian cochlea. SK2 is expressed in both inner and outer hair cells, and it plays an important role in the auditory system. The coding region sequences of Shh and SK2 were obtained from a wide range of mammals with and without echolocating ability. The topologies of phylogenetic trees constructed using Shh and SK2 were different; however, multiple molecular evolutionary analyses showed that those two genes experienced different selective pressures in echolocating bats and toothed whales compared to non-echolocating mammals. In addition, several nominally significant positively selected sites were detected in the non-functional domain of the SK2 gene, indicating that different selective pressures were acting on different parts of the SK2 gene. This study has expanded our knowledge of the adaptive evolution of high-frequency hearing in echolocating mammals.

Review on pharmacological and phytochemical prospects of traditional medicinal plant: Persicaria hydropiper (Smartweed)

2021 ◽  
Vol 21 ◽  
Author(s):  
Abdul Nasir ◽  
Atif Ali Khan Khalil ◽  
Muhammad Zeeshan Bhatti ◽  
Ashfaq Ur Rehman ◽  
Jiayi Li ◽  
...  
Keyword(s):  
Medicinal Plant ◽  
Traditional Medicine ◽  
Northern Hemisphere ◽  
Biological Activities ◽  
Folk Medicine ◽  
Present Review ◽  
Polygonum Hydropiper ◽  
Wide Range ◽  
Pharmacological Data ◽  
Different Parts

: Persicaria hydropiper (L.) Delarbre (family Polygonacea), commonly known as Polygonum hydropiper, is a popular medicinal plant used in traditional medicine. The plant is indigenous to the tropical northern hemisphere and temperate zone including China, Bangladesh, India, and Japan. The plant is used in folk medicine for numerous ailments such as hemorrhoids, antifertility, diarrhea, and dyspepsia. Its medicinal usage in Unani, Ayurveda, Siddha, and other traditional medicine is well-recognized. So far, a wide range of active phytochemicals of this plant has been identified, such as flavonoids, sulphated flavonoids, terpenoids, anthraquinones, steroids, coumarin, simple phenolics, and others. Pharmacological data reported in the literature suggest that various parts of P. hydropiper exhibit antimicrobial, antioxidant, hypoglycemic, antidepressant, cardioprotective, hepatoprotective, anticancer, and antifertility effects. The present review aim is to compile the coherently document research on the phytochemical, pharmacological, and biological activities of P. hydropiper from different parts of the globe.

Membrane dynamics in insect malpighian tubules

1989 ◽  
Vol 257 (5) ◽  
pp. R967-R972
Author(s):  
T. J. Bradley
Keyword(s):  
Ion Transport ◽  
Driving Force ◽  
Fluid Secretion ◽  
Membrane Dynamics ◽  
Malpighian Tubules ◽  
Membrane Insertion ◽  
Cation Pump ◽  
Active Ion Transport ◽  
Urine Formation ◽  
Apical Membranes

Urine formation in insects occurs in the Malpighian tubules by means of active ion transport and osmotically coupled water flow. The rates of urine formation can vary with time and can be modulated by diuretic hormones, developmental events, and intracellular parasitism. This paper reviews a number of recent studies in which it has been demonstrated that variations in transport rate are associated with substantial changes in tubule ultrastructure in the form of membrane insertion into and deletion from the apical microvilli. The principal driving force for fluid movement in Malpighian tubules is thought to be a common cation pump located in the apical membranes. It is proposed that modulation of the apical microvillar membrane may reflect regulation by the cells of the number of common cation pump units involved in fluid secretion.

Comparative physiology of insect renal function

1981 ◽  
Vol 241 (5) ◽  
pp. R241-R257 ◽  
Author(s):  
J. Phillips
Keyword(s):  
Surface Area ◽  
Total Surface Area ◽  
Malpighian Tubules ◽  
Thick Ascending Limb ◽  
Small Surface ◽  
Multiplier System ◽  
Wide Range ◽  
Glomerular Filtrate ◽  
Unit Body Weight ◽  
Anion Transfer

Transport mechanisms and their control in various segments of insect excretory systems are reviewed and compared to those of vertebrate nephrons, exocrine glands, and hindguts. Formation of the primary urine in most insect Malpighian tubules (MT) is by isosmotic secretion, which is driven by an apical cation (K+) pump rather than by Na+-K+-ATPase. Unlike the glomerular filtrate of vertebrates, insect MT fluid is very different from the blood in composition, often having very high K+-to-Na+ ratios, and urine-to-plasma values much less than unity for most other solutes. The total surface area of insect MT is some 20 times that of vertebrate glomeruli per unit body weight. Secretion of MT fluid is regulated by neuropeptides over a wide range of rats, similar to glomerular filtration rate values for many vertebrate kidneys. Several secretory mechanisms for selected solutes are probably common to insect and vertebrate tubules. Unlike vertebrates, insects usually reabsorb most of the filtered water, ions, and metabolites in the rectum, which has a small surface area relative to the MT. The rectum is also where ionic and osmotic composition of the excreta is finally adjusted, under the control of neuropeptide hormones. In the rectum, insect excreta can become as hyperosmotic as mammalian urine, even though a countercurrent multiplier system is not present. Active transport of Cl- predominates in both locust rectum and the thick ascending limb of Henle's loop, but the characteristics of the anion transfer process are quite different in these two epithelia.xs

scholarly journals Excretion by the Malpighian Tubules of the Stick Insect, Dixippus Morosus (Orthoptera, Phasmidae): Calcium, Magnesium, Chloride, Phosphate and Hydrogen Ions

1956 ◽  
Vol 33 (4) ◽  
pp. 697-708
Author(s):  
J. A. RAMSAY
Keyword(s):  
General Problem ◽  
Magnesium Chloride ◽  
Liquid Paraffin ◽  
Stick Insect ◽  
Urine Flow ◽  
Malpighian Tubules ◽  
Hydrogen Ions ◽  
Calcium Magnesium

1. The excretion of calcium, magnesium, chloride, phosphate and hydrogen ions has been studied in preparations of single Malpighian tubules isolated in drops of serum under liquid paraffin. 2. The concentrations of calcium, magnesium and chloride are always lower in the urine than in the serum. 3. The concentration of phosphate is always greater in the urine than in the serum. As the concentration of phosphate in the serum increases, the rate of urine flow also increases. 4. The urine is always alkaline to the serum but becomes acid in the rectum. 5. The general problem of excretion by Malpighian tubules is briefly reviewed and discussed.

scholarly journals Prevalence of Musculoskeletal Disorders among Dentists in Al-Madinah, Kingdom of Saudi Arabia

2017 ◽  
Vol 03 (01) ◽  
pp. 015-019
Author(s):  
Talat Al-Gunaid ◽  
Rayan Abdulhai ◽  
Baha Flemban
Keyword(s):  
Saudi Arabia ◽  
Musculoskeletal Disorders ◽  
Dental Students ◽  
The Body ◽  
Musculoskeletal Symptoms ◽  
Kingdom Of Saudi Arabia ◽  
Increased Risk ◽  
Dental Practitioners ◽  
Wide Range ◽  
Different Parts

Abstract Introduction: Musculoskeletal disorders (MSDs) are one of the most common occupational hazards associated with a wide range of occupations. Dental professionals have an increased risk of developing such disorders caused by repetitive, hard, or stressful gestures. Taking this issue into consideration, we felt the necessity to investigate the prevalence and distribution of musculoskeletal symptoms among dentists in Al-Madinah. Materials and methods: A self-reported questionnaire was distributed to a random sample of 180 dentists from different parts of Al-Madinah, Kingdom of Saudi Arabia. The questionnaire was about musculoskeletal symptoms in different parts of the body. Results: A total of 70 questionnaires were completed and returned. Of the respondents, 47 (67.1%) were males and 23 (32.9%) were females. The mean age of respondents was 36.1 ± 8.7. Majority were general dental practitioners [45 (64.2%)], with the remainder being specialists [25 (35.8%)]. Prevalence of MSD during the past 12 months was reported to be lower back pain (65.7%), neck pain (48.6%), and shoulder pain (45.7%), with the lowest prevalence pain being found in the hips and thighs (17.1%). Conclusion: The results suggested that the prevalence of musculoskeletal symptoms among dentists in Al-Madinah, Kingdom of Saudi Arabia, is high. Continuing education for dentists and dental students about the proper and correct dental positions as well as practicing ergonomic skills and incorporating them into the curriculum would be beneficial.

Occurrence and Significance of Toxic Cyanobacteria in Southern Africa

1991 ◽  
Vol 23 (1-3) ◽  
pp. 175-180 ◽  
Author(s):  
W. E. Scott
Keyword(s):  
South Africa ◽  
Southern Africa ◽  
Single Species ◽  
Practical Significance ◽  
Toxic Species ◽  
Toxic Cyanobacteria ◽  
Cyanobacterial Species ◽  
Wide Range ◽  
Toxic Blooms ◽  
Different Parts

A comprehensive list is provided of more than forty cyanobacterial species and genera reported to have toxic properties. In South Africa the majority of animal poisonings since 1927 have been caused by a single species Microcystis aeruginosa. Although other toxic species also occur in southern Africa, to date they have been of little practical significance. The widespread distribution of M. aeruginosa throughout southern Africa indicates a tremendous potential for toxic blooms to develop with increasing eutrophication. Using HPLC techniques up to six different toxin variants have been quantified in natural blooms of M. aeruginosa collected in different parts of South Africa. The amounts and proportions of the different toxins in the different samples varied over a wide range. Several additional unidentified toxins were detected.

RECOGNITION OF PERSIAN ONLINE HANDWRITING USING ELASTIC FUZZY PATTERN RECOGNITION

2007 ◽  
Vol 21 (03) ◽  
pp. 491-513 ◽  
Author(s):  
RAMIN HALAVATI ◽  
SAEED BAGHERI SHOURAKI
Keyword(s):  
Linguistic Terms ◽  
Input Stream ◽  
Cursive Handwriting ◽  
Novel Approach ◽  
Wide Range ◽  
Fuzzy Pattern ◽  
School Books ◽  
Fuzzy Linguistic ◽  
Online Handwriting ◽  
Different Parts

Persian is a fully cursive handwriting in which each character may take different forms in different parts of the word, characters overlap and there is a wide range of possible styles. These complexities make automatic recognition of Persian a very hard task. This paper presents a novel approach on recognition of such writings systems which is based on the description of input stream by a sequence of fuzzy linguistic terms; representation of character patterns with the same descriptive language; and comparison of inputs with character patterns using a novel elastic pattern matching approach. As there is no general benchmark for recognition of Persian handwriting, the approach has been tested on the set of words in first primary Iranian school books including 1250 words resulting in 78% correct recognition without dictionary and 96% with dictionary.

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