The ultrastructure and metabolism of ejaculated tammar wallaby sperm are impaired by swim-up procedures when compared with sperm from the cauda epididymidis

1999 ◽  
Vol 11 (5) ◽  
pp. 263 ◽  
Author(s):  
R. N. Murdoch ◽  
R. C. Jones ◽  
M. Wade ◽  
M. Lin
Keyword(s):  
Tammar Wallaby ◽  
Ultrastructural Changes ◽  
Intracellular Accumulation ◽  
Epididymal Sperm ◽  
Metabolism Rate ◽  
Subsequent Exposure ◽  
Ultrastructural Damage ◽  
Metabolic Properties ◽  
Cauda Epididymidis ◽  
Induced Changes

The metabolism, rate of intracellular accumulation of sugars, motility and ultrastructure of ejaculated tammar sperm were impaired by swim-up into artificial media, particularly when the cells were subsequently exposed to N-acetyl-D-glucosamine (NAG). The inclusion of hyaluronate, serum albumin, catalase or Desferal in swim-up media helped prevent deterioration of sperm motility, but failed to prevent detrimental NAG-induced metabolic and ultrastructural changes. However, the sperm were unavoidably diluted during swim-up into artificial media and their behavioural properties were modified by dilution. Thus, sperm collected from the cauda epididymidis were immotile and their rate of oxygen uptake was low in undiluted caudal epididymal semen (CES). Nevertheless, these sperm were viable, and vigorous motility was induced by 5- to 50-fold dilution in Krebs-Ringer phosphate (KRP). Sperm respiration also dramatically increased with moderate dilution (5- or 15-fold) in KRP, but decreased again at higher rates (50-fold). This suggested that motility and the metabolic properties of tammar sperm are modified both by dilution and on leaving the suppressing conditions of the epididymis. Diluted tammar epididymal sperm also displayed a Pasteur effect, but rapidly lost capacity for motility in an oxygen-depleted atmosphere. It was concluded hat swim-up procedures compromise ejaculated tammar sperm by promoting dilution-induced changes. This may alter the permeability of the membrane with loss of the enzymes that process the ammonia generated during the metabolism of NAG in seminal plasma. Subsequent exposure to NAG further promotes ultrastructural damage culminating in loss of viability.

Vasopressin- and cAMP-induced changes in ultrastructure of isolated perfused inner medullary collecting ducts

1993 ◽  
Vol 265 (2) ◽  
pp. F225-F238 ◽  
Author(s):  
S. Nielsen ◽  
J. Muller ◽  
M. A. Knepper
Keyword(s):  
Water Permeability ◽  
Apical Membrane ◽  
Endocytic Pathway ◽  
Ultrastructural Changes ◽  
Osmotic Water Permeability ◽  
Intercellular Spaces ◽  
Osmotic Water ◽  
Collecting Ducts ◽  
Induced Changes ◽  
Camp Stimulation

Studies were performed to correlate arginine vasopressin (AVP)-induced changes in epithelial ultrastructure with changes in osmotic water permeability in isolated perfused rat terminal inner medullary collecting ducts (tIMCD). The tubules were perfused in three time periods, i.e., a 40-min basal period, a 40-min period with 0.1 nM AVP in the bath, and a 60-min withdrawal period. In each phase, the osmotic water permeability (Pf) was measured, and the perfused tubules were fixed for electron microscopy. AVP caused a four- to eightfold increase in Pf and induced several ultrastructural changes as follows: increased cell height of IMCD cells, expansion of the intercellular spaces, formation of large vacuoles, and increased coated pit density in the apical plasma membrane [from 0.6 +/- 0.2 (n = 6) to 2.9 +/- 0.3 (n = 7) pits/100 microns membrane length]. During AVP withdrawal, Pf decreased toward the basal value in association with partial reversal of the ultrastructural changes including a decrease in coated pit density to 1.0 +/- 0.2 (n = 4). Stimulation with 8-bromoadenosine 3',5'-cyclic monophosphate (8-bromo-cAMP) (0.1 mM) produced similar changes in Pf. Coated pit density increased to 2.1 +/- 0.4 (n = 4) after cAMP stimulation and after cAMP withdrawal decreased to 1.2 +/- 0.2 (n = 6). In contrast to stimulation with AVP, cAMP stimulation did not result in dilated intercellular spaces or formation of large vacuoles. The only ultrastructural feature that directly correlated with the water permeability was the density of coated pits in the apical membrane. Organelles involved in the endocytic pathway were studied with cationized ferritin or albumin-gold in the luminal perfusate. At the end of 40 min basal perfusion or AVP stimulation, luminal tracer was found almost exclusively in large multivesicular bodies (MVB). Tubules perfused with tracer during AVP withdrawal demonstrated rapid tracer accumulation in small vesicles and small MVB within 3-5 min, a time point corresponding to the rapid phase of Pf decrease. Later (30-60 min) the label was mainly confined to large MVB. Occasionally during AVP stimulation or withdrawal, small coated vesicles and smooth vesicles with coated extensions were noted to contain tracer. The data demonstrate AVP-mediated coated pit formation and cellular changes and show very rapid internalization of apical membrane after AVP withdrawal.

Role of free radicals in catecholamine-induced cardiomyopathy

1982 ◽  
Vol 60 (11) ◽  
pp. 1390-1397 ◽  
Author(s):  
P. K. Singal ◽  
N. Kapur ◽  
K. S. Dhillon ◽  
R. E. Beamish ◽  
N. S. Dhalla
Keyword(s):  
Free Radicals ◽  
Vitamin E ◽  
Creatine Phosphate ◽  
Normal Diet ◽  
Ultrastructural Changes ◽  
Antioxidant Vitamin ◽  
Deficient Diet ◽  
Increased Sensitivity ◽  
Increase Membrane Permeability ◽  
Induced Changes

Effects of an antioxidant, vitamin E, and a membrane stabilizing agent, zinc, were examined on the isoproterenol-induced changes in the rat myocardium. Isoproterenol treatment (80 mg/kg given over 2 days in two equal doses) caused arrhythmias and 25% mortality within 24 h of the last injection. The ultrastructural changes in the subendocardium and in focal areas of the subepicardium included swelling of mitochondria, loss of myofibrils, cell necrosis, fibrosis, and infiltration of the affected areas by polymorphonucleocytes. Both creatine phosphate and adenosine triphosphate levels were markedly decreased in hearts from isoproterenol-treated animals. Pretreatment of the animals with vitamin E (10 mg∙kg−1∙day−1 for 2 weeks) or zinc (10 mg/kg ZnSO4, twice a day for 7 days) prevented these deleterious effects of isoproterenol. Animals maintained on vitamin E deficient diet for 8 weeks were found to be more sensitive to isoproterenol-induced changes and this increased sensitivity was reversed by a 2-week feeding of the animals on the normal diet coupled with vitamin E treatment. Based on the data obtained in this study it is proposed that catecholamine-induced changes may involve free radicals, which by promoting lipid peroxidation may increase membrane permeability and lead to the development of cardiomyopathy.

Effects of SO2, O3, and SO2 and O3 in combination on photosynthesis and ultrastructure of two lichen species

1987 ◽  
Vol 65 (9) ◽  
pp. 1806-1818 ◽  
Author(s):  
Sharon Eversman ◽  
Lorene L. Sigal
Keyword(s):  
Electron Micrographs ◽  
Lichen Species ◽  
Ultrastructural Changes ◽  
Starch Grains ◽  
Low Concentrations ◽  
Ultrastructural Damage ◽  
Flavoparmelia Caperata ◽  
Umbilicaria Mammulata

Flavoparmelia caperata (L.) Hale and Umbilicaria mammulata (Ach.) Tuck, were exposed to 262 μg SO2 m−3, 59 μg O3 m−3, and 262 μg SO2 m−3 in combination with 59 μg O3 m−3 for 20 h over a 5-day period. Photosynthesis and ultrastructural observations were made after 12 and 20 h. At these low concentrations of pollutants, ultrastructural changes preceded and accompanied decreases in photosynthesis rates. Ozone was more phytotoxic than SO2. Ultrastructural damage was least with SO2 and greater and very similar with O3 and the combination of O3 and SO2. Photosynthetic data showed that SO2 ameliorates effects of O3. Electron micrographs showed increased accumulation of starch and cavity space around starch grains in the chloroplast and increased lipids in the cytoplasm in F. caperata; there was some increased starch in U. mammulata, but alterations were primarily in increased chloroplast opacity. Photosynthesis of U. mammulata was more sensitive to the pollutants than that of F. caperata. Ultrastructural damage was greater when samples were stored in the light than when they were stored in the dark between fumigations. The study shows that species vary in their responses to pollutants and that combinations of pollutants may give results different from those obtained with single pollutants.

scholarly journals Flexible conformation in organic matter coatings: An hypothesis about soil water repellency

2000 ◽  
Vol 80 (1) ◽  
pp. 143-152 ◽  
Author(s):  
J. L. Roy ◽  
W. B. McGill
Keyword(s):  
Soil Water ◽  
Conformational Changes ◽  
Contaminated Soils ◽  
Water Repellency ◽  
Supporting Evidence ◽  
Soil Water Repellency ◽  
Nonpolar Solvents ◽  
Causative Agents ◽  
Subsequent Exposure ◽  
Induced Changes

Some soils develop severe water repellency several years or decades following oil contamination. We previously reported that soil water repellency is completely eliminated by extraction with amphiphilic solvents, but barely reduced by extraction with nonpolar solvents. We report here on solvent-induced reversible soil water repellency. Our results indicate that: (i) water repellency is completely eliminated following extraction with amphiphilic solvent, but partially restored following subsequent exposure to nonpolar, non-H-bonding solvent; (ii) extraction with nonpolar, non-H-bonding solvent generates water repellency in readily wettable control wettable soils, but not in pristine wettable soils, and (iii) repeated sequential extractions alternating between amphiphilic and nonpolar, non-H-bonding solvent increase extractable material and reduce the magnitude of solvent-induced soil water repellency with time.We attribute reversible soil water repellency to solvent-induced changes in the conformation of causative agents of soil water repellency. Recent literature reports on the structural flexibility of "insoluble" organic macromolecules are discussed for supporting evidence. We propose that exposure to nonpolar, non-H-bonding solvents induces stretching of surface-exposed, nonpolar moieties (i.e. alkyl chains), whereas exposure to polar, H-bonding solvents induces their coiling. These solvent-induced conformational changes are retained upon solvent removal. Our results indicate that the wettability of oil-contaminated soils depends on both the interfacial conformation and the fractional coverage of their surface-exposed nonpolar moieties. Key words: Soil water repellency, crude oil, hydrophobic soil, conformational flexibility, swelling, solvents

scholarly journals Olmesartan Attenuates Tacrolimus-Induced Biochemical and Ultrastructural Changes in Rat Kidney Tissue

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Naif O. Al-Harbi ◽  
Faisal Imam ◽  
Mohammed M. Al-Harbi ◽  
Muzaffar Iqbal ◽  
Ahmed Nadeem ◽  
...  
Keyword(s):  
Renal Damage ◽  
Calcineurin Inhibitor ◽  
Renal Tubule ◽  
Rat Kidney ◽  
Kidney Tissue ◽  
Immunosuppressive Agent ◽  
Ultrastructural Changes ◽  
Protective Effects ◽  
Ultrastructural Studies ◽  
Induced Changes

Tacrolimus, a calcineurin inhibitor, is clinically used as an immunosuppressive agent in organ transplantation, but its use is limited due to its marked nephrotoxicity. The present study investigated the effect of olmesartan (angiotensin receptor blocker) on tacrolimus-induced nephrotoxicity in rats. A total of 24 rats were divided into four groups, which included control, tacrolimus, tacrolimus + olmesartan, and olmesartan groups. Tacrolimus-induced nephrotoxicity was assessed biochemically and histopathologically. Tacrolimus significantly increased BUN and creatinine level. Treatment with olmesartan reversed tacrolimus-induced changes in the biochemical markers (BUN and creatinine) of nephrotoxicity. Tacrolimus significantly decreased GSH level and catalase activity while increasing MDA level. Olmesartan also attenuated the effects of tacrolimus on MDA, GSH, and catalase. In tacrolimus group histological examination showed marked changes in renal tubule, mitochondria, and podocyte processes. Histopathological and ultrastructural studies showed that treatment with olmesartan prevented tacrolimus-induced renal damage. These results suggest that olmesartan has protective effects on tacrolimus-induced nephrotoxicity, implying that RAS might be playing role in tacrolimus-induced nephrotoxicity.

scholarly journals Ultrastructural Localization of Calcium in Ischemic Hippocampal Slices: The Influence of Adenosine and Theophylline

1992 ◽  
Vol 12 (3) ◽  
pp. 520-524 ◽  
Author(s):  
Ernö Dux ◽  
Peter Schubert ◽  
Georg W. Kreutzberg
Keyword(s):  
Morphological Changes ◽  
Hippocampal Slices ◽  
Ultrastructural Localization ◽  
Free Medium ◽  
Adenosine Receptor Antagonist ◽  
Ca1 Region ◽  
Calcium Sequestration ◽  
Ultrastructural Damage ◽  
Induced Changes ◽  
Neuroprotective Action

Calcium was localized ultrastructurally with the use of the modified oxalate-pyroantimonate reaction in the CA1 region of rat hippocampal slices. Ten-minute ischemia (incubation with anoxic and glucose-free medium) followed by 30 min reoxygenation resulted in mitochondrial calcium sequestration and ultrastructural damage. The addition of the adenosine receptor antagonist, theophylline, worsened the ischemia-induced morphological changes and particularly exaggerated the Ca2+ loading in the postsynaptic dendrites. In contrast, adenosine protected against ischemia-induced changes. The results suggest that adenosine exerts its neuroprotective action largely by maintaining intracellular calcium-homeostasis.

Protein synthesis and secretion by the epididymis of the tammar wallaby, Macropus eugenii (Macropodidae: Marsupialia)

1992 ◽  
Vol 4 (5) ◽  
pp. 533 ◽  
Author(s):  
G Chaturapanich ◽  
RC Jones ◽  
J Clulow
Keyword(s):  
Protein Synthesis ◽  
Protein Secretion ◽  
Tammar Wallaby ◽  
Secreted Proteins ◽  
Blood Proteins ◽  
Macropus Eugenii ◽  
Cauda Epididymidis

The objectives were to assess the following in a marsupial: which proteins are synthesized by the different regions of the epididymis and secreted into the lumen of the ductus; the effect of the experimental method on the detection of protein secretion; the role of the testis in regulating the protein synthesis and secretion; and whether any of the secreted proteins may associate with spermatozoa. Samples from untreated animals were collected for examination by perfusing Krebs-bicarbonate through the ductus epididymidis in vivo (microperfusion), and after incorporation of [35S]methionine during incubation of minced duct in vitro. Electrophoresis of the samples showed that the caput and corpus epididymidis (initial segments) secreted most of the proteins that were synthesized and secreted by the epididymal mucosa, and that the cauda epididymidis secreted mainly blood proteins. Also, many more proteins were secreted in vitro than into the microperfusates in vivo, or were found by Jones (1987) in micropuncture samples of epididymal plasma. The synthesis and secretion of five proteins was androgen dependent (M(r) 75,700, 30,000, 18,700, 17,400 and 12,800). Also, the luminal fluids from the testis stimulated the secretion of two proteins (M(r) 46,300 and 36,100) and inhibited the secretion of three proteins (M(r) 43,000, 32,300 and 21,400). Examination of detergent extracts of spermatozoa indicated that they lose three proteins (M(r) 28,000, 30,000 and 47,000) and gain one (M(r) 30,400) during passage through the epididymis. The method of determining protein secretion affected the findings. Protein secretion, its control and its association with spermatozoa are broadly similar in the tammar wallaby to the processes described in eutherian mammals.

scholarly journals Artificial light at night desynchronizes strictly seasonal reproduction in a wild mammal

2015 ◽  
Vol 282 (1816) ◽  
pp. 20151745 ◽  
Author(s):  
Kylie A. Robert ◽  
John A. Lesku ◽  
Jesko Partecke ◽  
Brian Chambers
Keyword(s):  
Maternal Investment ◽  
Population Level ◽  
Tammar Wallaby ◽  
Urban Environments ◽  
Day Length ◽  
Artificial Light ◽  
Light At Night ◽  
Night Time ◽  
Induced Changes ◽  
Seasonally Breeding

Change in day length is an important cue for reproductive activation in seasonally breeding animals to ensure that the timing of greatest maternal investment (e.g. lactation in mammals) coincides with favourable environmental conditions (e.g. peak productivity). However, artificial light at night has the potential to interfere with the perception of such natural cues. Following a 5-year study on two populations of wild marsupial mammals exposed to different night-time levels of anthropogenic light, we show that light pollution in urban environments masks seasonal changes in ambient light cues, suppressing melatonin levels and delaying births in the tammar wallaby. These results highlight a previously unappreciated relationship linking artificial light at night with induced changes in mammalian reproductive physiology, and the potential for larger-scale impacts at the population level.

Morphometry of the epididymis of the tammar wallaby, Macropus eugenii, and estimation of some physiological parameters

1991 ◽  
Vol 3 (6) ◽  
pp. 651 ◽  
Author(s):  
G Chaturapanich ◽  
RC Jones
Keyword(s):  
Tammar Wallaby ◽  
Sperm Storage ◽  
High Ratio ◽  
Sperm Velocity ◽  
Macropus Eugenii ◽  
Ductuli Efferentes ◽  
Morphometric Features ◽  
Cauda Epididymidis ◽  
Testis Mass ◽  
Caput Epididymidis

About 14 ductuli efferentes (mean length 48 cm) leave the testis of the tammar. The caput, corpus and cauda epididymidis constitute 37%, 42% and 21% respectively of the total length of the ductus epididymidis (estimated to be 34.9 m long). The initial segments of the ductus epididymidis are longer, relative to body or testis mass, in the tammar than in eutherian mammals such as the rat. The main morphometric features of the male excurrent duct system of the tammar are a high ratio of surface area of luminal border:luminal volume of the ductuli efferentes (which reabsorb most of the fluid leaving the testis), a high ratio of epithelial volume:luminal volume in the caput and corpus epididymidis (which are involved in sperm maturation) and a low ratio of epithelial volume:luminal volume in the cauda epididymidis (which is involved in sperm storage). Estimates of fluid reabsorption by the ductuli efferentes and protein secretion by the caput epididymidis were respectively 8.9 microL cm-2h-1 and 2.8 micrograms cm-2h-1. Other estimates for the ductuli efferentes, caput, corpus and cauda epididymidis respectively were: sperm velocity (4.5, 4.8, 2.2, and 0.9 mm min-1), duration of sperm transit (107 min, 1.9 days, 4.7 days, and 6.3 days), total number of spermatozoa (4950 x 10(6)) and distribution of extragonadal spermatozoa (0.6, 14, 36 and 49% of the total). The values are within the ranges estimated for eutherian mammals.

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