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PubMed1988

Rhabdomere turnover and rhodopsin cycle: maintenance of retinula cells in Drosophila melanogaster.

Visual receptor maintenance in Drosophila involves turnover of membrane. Coated pits derived from rhabdomere and plasmalemma, coated vesicles and multivesicular bodies (MVBs) of about 0.5 micron diameter characterize the early autophagic steps. Smaller electron dense bodies (0.15 micron) merge with MVBs. These are likely to be primary lysosomes as suggested by histochemistry for acid phosphatase in normal flies and an acid phosphatase deficient mutant. Aggregates of extracellular membranes confirm an earlier report that exocytotic shedding may also be employed in the fly with its open rhabdomeres. Microspectrophotometry was used to determine aspects of cycling of visual pigment to begin to correlate with what is known about membrane cycling at the ultrastructural level. Visual pigment decreases to about half 3 h after dawn then builds back gradually to maximum before dawn. Our fixations of tissue have been at the post-dawn period when autophagy may be high as inferred from visual pigment levels. In attempts to optimize our visualization of the constructive phase of the turnover process, we developed the paradigm of carotenoid 'replacement therapy'. Carotenoid replaced flies show an increase in visual pigment possibly associated with a streaming of membrane into the rhabdomere. Aged flies, studied to determine how effective maintenance is, have a unique accumulation of extracellular debris, and a small fraction of the receptors eventually degenerate.

Acid Phosphatase↗
PubMed1988

Neurogenic inflammation in the rat trachea. II. Identity and distribution of nerves mediating the increase in vascular permeability.

This study addresses the question of whether increased vascular permeability, which is a prominent feature of neurogenic inflammation in the respiratory tract, is mediated by sensory axons that end near venules in the airway mucosa. In these experiments, neurogenic inflammation was produced in the tracheal and bronchial mucosa of atropine-treated Long-Evans rats by electrical stimulation of the left or right superior laryngeal nerve and/or cervical vagus nerve. The particulate tracer Monastral blue was injected intravenously to localize the sites of increased vascular permeability, and microspectrophotometry was used to measure the amount of extravasated Monastral blue in the trachea and thereby quantify the increase in vascular permeability. In some rats, selective denervations were made to locate the cell bodies of neurons that mediate the increase in vascular permeability; in others, fluorescence immunohistochemistry and quantitative electron microscopic methods were used to determine which structures in the tracheal mucosa are innervated by these neurons. The study revealed that the vagally mediated increase in vascular permeability was sudden, transient (half-life = 2.4 min) and restricted to venules. Stimulation of the left or right superior laryngeal nerve increased the permeability of venules in the extrathoracic trachea, whereas stimulation of either vagus nerve increased vascular permeability in the intrathoracic trachea and bronchi. All nerves had bilateral effects in the trachea, but the vagus nerves had largely unilateral effects in the bronchi. Neurons that mediated the increase in venular permeability had their cells bodies in the jugular (superior sensory) ganglion of the vagus nerve or rostral portion of the nodose (inferior sensory) ganglion. Preganglionic autonomic vagal neurons in the brain stem were not essential for this increase in venular permeability. Few nerves identifiable by substance P-immunohistochemistry or electron microscopy were located near the affected venules, and no nerves were within 1 micron of the walls of venules. However, the epithelium and arterioles of the airway mucosa were densely innervated. All intraepithelial nerves were within 0.1 micron of epithelial cells, and at least two-thirds of nerves near arterioles were within 1 micron of the vessel walls. We conclude that the increase in venular permeability associated with neurogenic inflammation in the trachea and bronchi of rats is mediated by sensory axons that travel in the vagus nerves and superior laryngeal nerves.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Genomic amplification in the cotyledon parenchyma of common bean.

The cotyledon parenchyma cells of common bean (Phaseolus vulgaris L.) produce large quantities of storage proteins during embryo maturation; throughout this period, these cells also accumulate nuclear DNA (nDNA). To investigate the basis of this nDNA accumulation, we have measured storage protein mRNA pools, nDNA mass, and gene copy number at specific stages of cotyledon development. RNA blotting and hybridization show that transcripts encoding the major embryo-specific storage proteins are present very early in cotyledon development, accumulate in coordinate fashion to peak during mid-maturation, and fall in abundance prior to the onset of dormancy. During this same period, nDNA mass per parenchyma cell nucleus, as measured by Feulgen microspectrophotometry, increases from 2C-4C to about 64C (C being the haploid germ cell genomic complement). The nDNA values do not cluster around integral multiples of the diploid 2C amount. DNA blotting and hybridization are used to evaluate the relative representations of different classes of the bean genome in DNA samples isolated from vegetative tissues, from cotyledons beginning to accumulate storage proteins, and from cotyledons of late maturation embryos entering dormancy. The results demonstrate that the observed DNA accumulation in the cotyledon parenchyma is due to overlapping rounds of replication of the complete genome and not to disproportionate amplification of specific sequences nor to random DNA synthesis.

Cell Nucleus↗
PubMedDate not supplied

Myocardial O2 supply and consumption in early cardiac hypertrophy of renal hypertensive rabbits.

This study examined myocardial O2 supply and O2 consumption in hypertension-induced myocardial hypertrophy. New Zealand white rabbits prepared as uninephrectomized (sham) controls (n = 7), or one kidney/one clip (1K1C) hypertensive rabbits (n = 7) were examined four weeks after surgery. A group of renally intact "true" controls (n = 4) was also examined. Coronary blood flow (CBF) was measured with radioactive microspheres in anesthetized open chest animals during baseline and vasodilated conditions (adenosine, 0.4 mg/kg/min). Microvascular O2 saturations were determined by microspectrophotometry. Myocardial oxygen consumption (MVO2) was calculated. Mean pressure was elevated in hypertensive animals (121 +/- 7 mmHg, means +/- SE) compared to uninephrectomized controls (74 +/- 7 mmHg). Hypertrophy was indicated by a 30% increase in heart weight to body weight ratio in the 1K1C animals. The average MVO2 was elevated in hypertrophy (12.4 +/- 0.9 vs. 9.6 +/- 0.8 ml O2/min/100 g). Baseline CBF was higher in cardiac hypertrophy (227 +/- 21 ml/min/100 g) compared to sham controls (169 +/- 14 ml/min/100 g). In hypertrophy the percent increase in CBF during adenosine infusion was reduced and the minimal vascular resistance was higher. No difference in microvascular O2 saturations was observed between groups, thus O2 extraction was similar. No subepicardial vs. subendocardial difference occurred within either the sham controls or the 1K1C animals in any parameter. Therefore, an overall increased MVO2 resulted in increased CBF and reduced coronary flow reserve in short-term renovascular hypertension-induced cardiac hypertrophy in rabbits.

Animals↗
PubMedDate not supplied

Effect of complement depletion on O2 supply and consumption in ischemic dog myocardium.

The purpose of this study was to determine whether depletion of serum complement can decrease the severity of an ischemic episode by improving regional O2 supply and consumption parameters in the ischemic region of the heart. Fourteen anesthetized dogs with serum complement intact or depleted (100 U/kg cobra venom factor given 8 hrs before) were subjected to left anterior descending coronary artery (LAD) occlusion for 6 hrs. Myocardial blood flows were determined before and 6 hrs after LAD occlusion using radioactive microspheres. Regional arterial and venous O2 saturations were determined using microspectrophotometry. In control animals, flow decreased from 122 +/- 42 to 13 +/- 14 ml/min/100 g (mean +/- SD) in the occluded LAD region. With complement depletion, LAD occlusion resulted in a flow reduction in the ischemic region (38 +/- 29 ml/min/100 g), but to a lesser degree than seen in the same region in control animals, especially in the subendocardium. O2 consumption was decreased in the ischemic region of both treatment groups, though O2 consumption was higher in this region in complement depleted animals compared to the values in control animals. The O2 supply/consumption ratio was decreased similarly in the ischemic region of control and complement depleted groups. Thus, with complement depletion, flow to the ischemic zone was improved but this region was still flow restricted. The flow increase during complement depletion was sufficient to allow an increased O2 utilization in the ischemic region.

Animals↗
PubMedDate not supplied

Propranolol and thyroxine-induced hypertrophic rabbit hearts: effect on heart size and regional O2 supply/consumption variables.

The purpose of this study was to determine the effect of acute and chronic propranolol on heart size and regional O2 supply/consumption variables in thyroxine (T4)-treated rabbit hearts. New Zealand white rabbits were given 0.5 mg/kg T4 for 3 or 16 days with and without concomitant 2 mg/kg propranolol. Another group was given 16 days of propranolol alone and another 3-day T4 group was given 2 mg/kg propranolol 1 h before the experiment began. Another group served as control. Myocardial blood flows were determined using radioactive microspheres and small arteriolar and venous O2 saturations were determined using microspectrophotometry. Treatment with T4 for 3 or 16 days increased the heart weight/body weight ratio, myocardial blood flow, and regional O2 consumption. 16-day T4 treatment resulted in myocardial flow 195% and O2 consumption 300% above control group values. When propranolol was given chronically along with T4, heart weight/body weight ratios did not increase to the degree seen with 3 or 16 days of T4, alone. Propranolol given acutely in 3-day T4-treated animals, resulted in a reduced O2 consumption and O2 extraction, though not to the extent seen with chronic propranolol treatment of T4-treated animals. Acute propranolol treatment slightly reduced myocardial blood flow in 3-day T4-treated animals, while chronic treatment significantly reduced it. Chronic propranolol treatment in 16-day T4-treated animals resulted in a significant reduction in flow and O2 consumption. Thus, T4 treatment increased O2 consumption, flow, and heart size and these effects could be attenuated using acute and chronic propranolol.

Animals↗
PubMedDate not supplied

Regional oxygen supply and consumption balance in experimental left ventricular hypertrophy.

The aim of the present study was to determine if the relationship between myocardial O2 supply and O2 consumption was preserved after prolonged pressure overload due to aortic valve stenosis. This was examined in anesthetized open-chest dogs in which the aortic valve was plicated 6 months previously. We measured coronary blood flow with radioactive microspheres and regional small vessel O2 saturation with microspectrophotometry, to obtain O2 supply, and O2 consumption. Regional O2 consumption was calculated as the product of flow and O2 extraction. The left ventricular weight/body weight ratio was 81% greater in the dogs with aortic valve stenosis. There were no hemodynamic differences between the groups except that left ventricular systolic pressure was 38 +/- 22 mm Hg greater than aortic in the hypertrophied group. Coronary blood flow did not differ between the control and hypertrophied groups nor were there subepicardial vs subendocardial differences. When maximal coronary flow was determined with chromonar (10 mg/kg), the flow increase was significantly attenuated in the hypertrophied subendocardium (242.1 +/- 82.3 (hypertrophy) vs 512.4 +/- 204.1 ml.min-1.100 g-1 (control). There were no significant differences in O2 extraction or O2 consumption/g between control and hypertrophied animals. There was a significantly lower O2 supply/consumption ratio in the subendocardium compared to the subepicardium of both groups. However, the O2 supply/consumption ratio was not decreased by hypertrophy. Thus, despite significant hypertrophy, a loss of flow reserve and a high left ventricular pressure, O2 supply/consumption balance is preserved in valvular aortic stenosis at rest.

Animals↗
PubMed1976

Trinucleate pollen in the genus Populus.

It is shown by light microscopy and microspectrophotometry that several Populus species produce trinucleate pollen. Such pollen seems more widespread than previously acknowledged.

Cell Nucleus↗
PubMedDate not supplied

Effect of dopamine on regional myocardial function and oxygen consumption in experimental left ventricular hypertrophy.

We investigated the hypothesis that the capacity of left ventricular myocardium to respond to an inotropic challenge by dopamine would be diminished in left ventricular hypertrophy induced by plication of the aortic valve. Seven mongrel dogs (LVH group) aged 6-8 weeks and weighing 4-6 kg, were subjected to preliminary surgery in which the noncoronary sinus of Valsalva was plicated. Six months later these animals, as well as a control group of dogs, were subjected to acute experiments in which the effect of dopamine (7.5 and 15 micrograms/kg/min) on regional and global myocardial function and oxygen consumption was studied. Myocardial segment length was measured with ultrasonic dimension transducers, and left ventricular and aortic blood pressures were recorded from catheter-tip transducers. Regional coronary blood flow was determined with radioactive microspheres, and regional oxygen saturation in small arteries and veins was measured using microspectrophotometry. Regional myocardial O2 consumption was calculated from these parameters. Heart weights were significantly elevated in the LVH group, and a pressure gradient of about 25 mm Hg was observed across the aortic valve. In both groups, dopamine infusion produced a dose-dependent increase in heart rate, left ventricular pressure, and LV dP/dtmax. Prior to dopamine infusion, percent shortening per beat was greater in the LVH group (13.97 +/- 1.2%) than in the control group (9.49 +/- 1.07%). Although the maximum speed of segment shortening was elevated by dopamine in both groups, percent shortening was not elevated in the LVH group. Stimulation by the high dose of dopamine produced a threefold elevation in regional coronary blood flow in both groups. Oxygen extraction was unchanged; the proportion of small veins with low O2 saturation was not elevated in LVH hearts, even during dopamine stimulation. Regional myocardial O2 consumption was elevated by dopamine (15 micrograms/kg/min) to about the same extent in both the control and LVH groups (19.1 +/- 2.3 and 17.5 +/- 2.3 ml O2/min/100 g) respectively. It is concluded that, in dogs with six months of aortic stenosis, dopamine does not exhaust functional reserve and the relationship between O2 supply and consumption is not significantly impaired.

Animals↗
PubMed1996

Safranin O reduces loss of glycosaminoglycans from bovine articular cartilage during histological specimen preparation.

The ability of Safranin O, added to fixation and decalcification solutions, to prevent the escape of glycosaminoglycans (GAGs) from small cartilage tissue blocks during histological processing of cartilage has been studied. GAGs in the fixatives and decalcifying solutions used and those remaining in the 1 mm3 cubes of cartilage were assayed biochemically. The quantity of GAGs remaining in the cartilage cubes were determined from Safranin O-stained sections using videomicroscopy or microspectrophotometry. A quantity (10.6%) of GAGs were lost during a conventional 4% buffered formaldehyde fixation (48 h) and a subsequent decalcification in 10% EDTA (12 days) at 4 degrees C. Roughly one-quarter of the total GAG loss occurred during the 48 h fixation, and three-quarters during the 12 days of decalcification. Inclusion of 4% formaldehyde in the decalcification fluid decreased the loss of GAGs to 6.2%. The presence of 0.5% Safranin O in the fixative reduced this loss to 3.4%. When 0.5% Safranin O was included in the fixative and 4% formaldehyde in the decalcification solution, Safranin O staining of the histological sections increased on average by 13.5%. After fixation in the presence of 0.5% Safranin O, there was no difference in the staining intensities when decalcification was carried out in the presence of either Safranin O or formaldehyde, or both. It took 24 h for Safranin O to penetrate into the deep zone of articular cartilage, warranting a fixation period of at least this long. In conclusion, the addition of Safranin O to the fixative and either Safranin O or formaldehyde in the following decalcification fluid, markedly reduces the loss of GAGs from small articular cartilage explants during histological processing. However, for immunohistochemical studies, Safranin O cannot be included in the processing solutions, because it may interfere.

Animals↗
PubMed1997

A comparison of CORVITA and expanded polytetrafluoroethylene vascular grafts implanted in the abdominal aortas of dogs.

The utility of CORVITA vascular grafts, composed of an inner layer of meshed polyurethane fibers and an outer layer of meshed Dacron reinforcement, for replacement of the abdominal aorta was assessed in a canine model and compared with expanded polytetrafluoroethylene (ePTFE) grafts. CORVITA or ePTFE vascular grafts were implanted and left in place for 3 or 6 months. After removal, they were inspected macroscopically and histologically. Microspectrophotometry was used to quantify smooth muscle cells (SMCs), elastin (EL), and collagen (CL) in the media of the native artery. The patency rate of the CORVITA grafts after 6 months was 100%, whereas that of the ePTFE grafts was only 50%. Moreover, stenoses were apparent in all of the ePTFE grafts, but in only 43% of the CORVITA grafts. The intimal thickness at the distal anastomosis was significantly greater at 3 months in the ePTFE grafts (P < 0.01), and there were significantly more SMCs in the host arterial media at the proximal and distal anastomoses in these grafts. Thus, better long-term patency can be expected with CORVITA grafts than with ePTFE grafts. This conferred advantage is most likely attributable to the less pronounced intimal hyperplasia which results from the proliferation of SMCs in the media of the native artery.

Anastomosis, Surgical↗
PubMed1992

Quantitative measurement of two-component pH-sensitive colorimetric spectra using multilayer neural networks.

The purpose of this research was to develop a noise tolerant and faster processing approach for in vivo and in vitro spectrophotometric applications where distorted spectra are difficult to interpret quantitatively. A PC based multilayer neural network with a sigmoid activation function and a generalized delta learning rule was trained with a two component (protonated and unprotonated form) pH-dependent spectrum generated from microspectrophotometry of the vital dye neutral red (NR). The network makes use of the digitized absorption spectrum between 375 and 675 nm. The number of nodes in the input layer was determined by the required resolution. The number of output nodes determined the step size of the quantization value used to distinguish the input spectra (i.e. defined the number of distinct output steps). Mathematic analysis provided the conditions for which this network is guaranteed to converge. Simulation results showed that features of the input spectrum were successfully identified and stored in the weight matrix of the input and hidden layers. After convergent training with typical spectra, a calibration curve was constructed to interpret the output layer activity and therefore, predict interpolated pH values of unknown spectra. With its built-in redundant presentation, this approach needed no preprocessing procedures (baseline correction or intensive signal averaging) normally used in multicomponent analyses. The identification of unknown spectra with the activities of the output layer is a one step process using the convergent weight matrix. After learning from examples, real time applications can be accomplished without solving multiple linear equations as in the multiple linear regression method.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydrogen-Ion Concentration↗
PubMed1996

Cyclic GMP-phosphodiesterase inhibition does not alter cerebral oxygen consumption.

The effect of zaprinast, a cyclic guanosine monophosphate inhibitor, on the level of cyclic GMP and cerebral O2 consumption was determined. Anesthetized male Long-Evans rats were divided into a control group (n = 15) and a zaprinast treated group (n = 15). Vehicle was applied topically to the left cortex and 3*10-3 M zaprinast was applied to the right cortex. A saline treated control group was also studied. Regional cerebral blood flow was determined by [14C]-iodoantipyrine and regional 0(2) extraction was determined by microspectrophotometry. The level of cyclic GMP was measured by radioimmunoassay. There were no hemodynamic or blood gas differences between groups. The level of cyclic GMP was not significantly different between the right and left cerebral cortex of the control group (17.0 + or - 4.3 and 17.7 + or - 4.6 pmol/g). In the zaprinast treated group, there was a significant (46%) increase in the level of cyclic GMP in the zaprinast treated cortex (20.5 + or - 8.1) in comparison to the vehicle treated cortex (14.0 + or - 5.7). Zaprinast did not significantly alter cerebral blood flow. There were no significant differences in regional 0(2) extraction. The 0(2) consumption of the zaprinast treated cortex (8.0 + or - 3.3 ml O(2)*min(-1)*100 g(-1)) was not different from that of the vehicle ) treated cortex (7.0 + or - 2.9) or those of the control group. Thus, our data indicated that the increased level of cyclic GMP had no significant effect on cerebral oxygen consumption.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1992

Effect of isoproterenol on regional myocardial segment work, O2 consumption, and oxygen balance.

We tested the hypothesis that positive inotropic stimulation by isoproterenol alters the relationship between regional segment work and regional myocardial oxygen consumption. Regional parameters were compared with external cardiac work and global LV oxygen consumption. In anesthetized open-chest dogs, regional myocardial segment length (ultrasonic dimension crystals) and force development (miniature force transducer) were measured. The integrated multiples of myocardial shortening by corresponding force during an averaged beat expressed segment work (area under the systolic portion of the length-force loop). External cardiac work was calculated from aortic blood pressure and cardiac output. Global and regional myocardial MVO2 were evaluated at baseline and during intravenous infusion of isoproterenol (0.5 and 1.0 micrograms/kg per min). Regional coronary blood flow was measured with radioactive microspheres, and microspectrophotometry of frozen myocardial biopsies was used to evaluate O2 saturation in small arteries and veins. These parameters were used to calculate regional MVO2. Arterial and coronary sinus O2 saturation was used to calculate global LV O2 consumption. Regional myocardial O2 balance was estimated by measurement of NADH redox level using surface fluorometry. It was found that 0.5 micrograms/kg per min isoproterenol increased regional segment work/minute from 4650 +/- 495 to 6750 +/- 750 mm.g/min. Corresponding regional oxygen consumption was disproportionately increased from 5.43 +/- 0.61 to 15.24 +/- 1.37 ml/min per 100 g. External cardiac work was found to decrease from 728 +/- 13 to 562 +/- 25 mmHg.1/min (due to decreased aortic blood pressure), whereas global myocardial O2 consumption increased. Regional myocardial O2 extraction and NADH fluorescence were elevated, indicating impaired tissue oxygenation. Regional MVO2 was increased by 153 +/- 56%, but regional work by only 45.3 +/- 33% (P < 0.05). These results indicate that regional contraction efficiency was markedly reduced by isoproterenol.

Animals↗
PubMed1979

Normal human endometrium in cell culture. II. A microspectrophotometric study of polyploid nuclei in short-term primary epithelial cultures.

The growth of short-term primary cultures of endometrial epithelium has been studied using Feulgen microspectrophotometry. A gradual increase in the number of polyploid nuclei up to 64C has been observed and is associated with a decline in the growth capacity of the cultures. The specific mechanism(s) of this polyploidization is not known.

Cell Nucleus↗
PubMed1976

Separation of mouse epidermal basal and differentiating cells for microflow fluorometric measurements: a methodologic study.

The DNA content of lymphocytes and of basal cells from normal hairless mouse epidermis was measured by microflow fluorometry (MFF). To obtain a relatively pure suspension of epidermal basal cells a combined mechanical and enzymatic method was used. The admixture of differentiating cells into the basal cell fraction after cell separation was 13%. The results were compared with those obtained with conventional Feulgen microspectrophotometry applied to basal cells and dermal lymphocytes in histologic sections. The results from both cytophotometric methods were in good agreement and clearly demonstrated the improved resolution obtained by using microflow fluorometry. When the lymphocytes were not treated with pepsin before being stained with ethidium bromide for MFF, the modal DNA value was consistently below that of the basal cells from the same specimen. Pepsin treatment of lymphocytes, however, increased their fluorescence intensity to the value of epidermal basal cells. The modal DNA value of Feulgen-stained dermal lymphocytes in histologic sections was consistently below that of epidermal basal cells from the same section. The advantage of pepsin treatment for obtaining higher resolution of DNA measurements of basal and differentiating epidermal cells and of lymphocytes was evaluated. The cell cycle distribution of basal cells from epidermis in different states of proliferative activity was determined. Changes in the proportion of cells in S phase were parallel to changes in the 3H-Tdr labeling index.

Animals↗
PubMed1999

Structure of peroxisomes and activity of the marker enzyme catalase in digestive epithelial cells in relation to PAH content of mussels from two Basque estuaries (Bay of Biscay): seasonal and site-specific variations.

The aim of the present work was to study the seasonal as well as the site-specific variations in the structure of peroxisomes and in the activity of the peroxisomal marker enzyme catalase in digestive epithelial cells of mussels to validate the potential use of these parameters as early biomarkers of environmental organic pollution in estuarine ecosystems. For this purpose, mussels were sampled monthly for 14 months in two Basque estuaries (Bay of Biscay) with different degrees of pollution. Stereological procedures were applied to detect changes in peroxisome structure, and microspectrophotometry was used to quantify changes in catalase activity. The animals from the two studied sampling sites presented differences in polycyclic aromatic hydrocarbon (PAH) burdens, mussels from Plentzia generally showing lower total PAH contents than mussels from Galea. The peroxisome structure of the animals from the two estuaries suffered seasonal variations that were of different kind and intensity in both sites. In this way, a strong peroxisome proliferatory response was found in mussels sampled in Plentzia during the summer months, while mussels from Galea presented few variations along the year. Catalase activity behaved similarly in the animals sampled in the two estuaries, with higher values in spring. It appeared that mussels exposed chronically to PAHs and other pollutants, such as those from Galea, lost their ability to respond to this exposure in terms of peroxisome proliferation. In contrast, mussels collected in Plentzia effectively responded to an increased bioavailability of organic pollutants during the summer by increasing peroxisome volume and surface and numerical densities in digestive epithelial cells. However, these increases were transient because elevated PAH body burdens detected in mussels sampled in Plentzia in autumn were not accompanied by a peroxisome proliferatory response. Further studies are needed before changes in peroxisomal structure and in the activity of catalase could be used as early biomarkers to assess environmental quality in pollution monitoring programs like the Mussel Watch.

Animals↗
PubMed2001

Visual pigments and optical habitats of surfperch (Embiotocidae) in the California kelp forest.

We studied the optical microhabitat use and visual pigment variation among a group of closely related teleosts (surfperch: Embiotocidae) living along the nearshore central California coast. We employed a diver-operated spectroradiometer to record the optical microhabitat use of eight surfperch species in Monterey Bay. and microspectrophotometry to measure visual pigment absorbance for nine surfperch species. Species were dichromatic with mixtures of A1- and A2-based visual pigments exhibiting extensive maximum absorbance (lambda(max)) variation across species: 455-482 nm for SWS cones and 527-546 nm for LWS cones. Interspecific variation in sidewelling irradiance measurements (mean lambdaFmaxs) significantly accounted for 63% of the variation in surfperch LWS visual pigments and 83% of the interspecific variation in SWS visual pigments using a phylogenetically-corrected regression technique. Optimality models for maximizing relative photon capture of background radiance demonstrate that the LWS cone lambda(max) values are tuned for maximizing photon capture of the species-specific horizontal visual field, while the SWS cone lambda(max), are well offset from the dominant background radiance. This study is one of the first to demonstrate species-specific differences in habitat usage at microhabitat scales accounting for differences in photoreceptor peak absorbance among closely related, sympatric species.

Animals↗