669 research outputs found
Telestula ridgensis Periasamy & Kurian & Ingole 2023, sp. nov.
No full textTelestula ridgensis sp. nov. Figs 1–8 Type material: holotype: Specimen, NCPOR /HYD-CIR/0048, Seamount of the Central Indian Ridge, Indian Ocean, R / V ‘ MGS Sagar’ cruise MGS–35 (Station MGS-35A-BD21), 24 April 2020, 23°10′28.92′′ S, 69°32′47.04′′ E, 1917 to 2053 m, Benthic Sledge, Coll. Periasamy R, samples in 90% ethanol. Paratypes: One specimen NCPOR /HYD-CIR/0049 from the same locality as the holotype. Ecological note: The specimen was collected along with two types of carnivorous sponges; three types of deepsea coral, three types of brittle stars, shrimps; and dead gastropod shells from medium-grained basalt rocky bottom with thick Fe-Mn crust. Coloration: The color of colonies ranges from yellowish-brown to dark brown or black; with their ends forming white or cream polyps. Distribution: Telestula ridgensis sp. nov. is known only for its type locality in the seamounts of the Central Indian Ridge system. Etymology: The specific name refers to the type locality of the Indian Ocean Ridge. Gender is feminine. Description Coral colonies are inter-connected with polyps by ribbon - like stolon expanding in irregular patterns on the surface of a dead coral (Fig. 2A), and budding of secondary polyps (Fig. 2C). The polyps arise from a ribbon - like stolon (0.6 mm in width). The holotype is about 19.7 mm tall and 0.2 mm in diameter, with eight polyps attached (Fig. 2D). Fully retracted polyps are up to 12 mm in height and 1.5 mm in width. Sclerites in the polyp (Fig. 3A,B,C) form a thick layer in the calyx wall region, being longitudinally arranged and tightly packed (Fig. 3D). The stolon is ribbon-shaped, with sclerites longitudinally arranged along the thin basal stolon (Fig. 3E). The sclerites in the tentacles and middle of the neck zone are transversely set (Fig. 4A, B,C). Tentacles sclerites are narrow and stellate plates; cross-like forms with slightly tubercular ornamentation; stellate plates (0.19– 0.06 mm long 0.08– 0.02 mm wide); cross-like sclerites (0.058 –0.082 mm long 0.047 –0.064 mm wide); smaller crosses, all of them with tubercular ornamentation (Fig. 5A). Pharyngeal sclerites are small warty plates (0.07–0.13 mm long, 0.010 –0.032 mm wide) (Fig. 5B). Neck zone sclerites are short, blunt rods, crosses with tubercular ornamentation; 0.16– 0.07 mm in length, 0.05– 0.01 mm wide; some crosses (Fig. 6A). I ntrusion sclerites are irregular-shaped, branched rods with tubercular ornamentation (0.14–0.52 mm long, 0.03–0.11 mm wide) (Fig. 6B). Calyx wall sclerites are irregular-shaped; crosses with dense tubercular ornamentation (0.45– 0.15 mm long 0.37– 0.06 mm wide); frequently with cross-like prominences (Fig.7A). Stolon sclerites are smooth to slightly warty plate,crosses; irregular-shaped with slightly tubercular ornamentation (0.40– 0.19 mm long 0.42– 0.02 mm wide); less cross-shaped forms (0.12– 0.25 mm long) (Fig. 7B). Remarks. The sclerome found in Telestula ridgensis sp. nov. is unique among the north-eastern Atlantic congeners having longitudinal rows of small warty rods and cross-like forms that extend from the distal end of the calyx towards the base of the tentacles. The sclerites of the new species from the neck zone, intrusion tissue, calyx wall, and ribbon-like stolon are notably different among the genus Telestula with an evident abundance of warty, irregular, and cylinder-like forms of small flattened ovals. Telestula ridgensis sp. nov. is morphologically closely related to Telestula septentrionalis, T. cf. batoni , and T. cf. spiculicula . According to Tixier-Durivault (1964) species, T. tubaria has eight chevrons of small sclerites in the neck region and eight longitudinal ridges of sclerites in a calyx wall. However, T. versluysi has densely tuberculate rounded spindles from the calyx wall and irregular spindles from the stolon (Weinberg 1990). T. mosaica has some arrowhead-like sclerites. The sclerites of T. kuekenthali have loose polyps, plump, coarsely tuberculate spindles from the calyx wall, irregular spindles, and cross-shaped sclerites from the top of the polyp (Weinberg 1990 ). Telestula stocki has plates on top of tentacles, sparse long spindles, warty spindles with complex tubercles, rods from stolon, and plump (Weinberg 1990).Published as part of Periasamy, Rengaiyan, Kurian, Palayil John & Ingole, Baban, 2023, A new deep-water coral species Telestula ridgensis sp. nov (Scleralcyonacea: Sarcodictyonidae) from the seamount of theCentral Indian Ridge, pp. 231-244 in Zootaxa 5254 (2) on pages 233-238, DOI: 10.11646/zootaxa.5254.2.4, http://zenodo.org/record/772729
Munidopsis parvatee Periasamy & Kurian & Ingole 2023, sp. nov.
No full textMunidopsis parvatee sp. nov. Fig 2–4 Material examined: female holotype: NCPOR /HYD–CIR/0048, ♀ (CL 14.2 mm, PCL 10.4 mm) Central Indian Ridge, Indian Ocean, R / V ‘ MGS Sagar’ cruise MGS35 (Station no: MGS35B– BD25), 27 April 2020, 24° 42′ 47.88′′ S, 70° 1′ 54.12′′ E, 1981 to 2033 m, Benthic Sledge, Coll. Periasamy R, samples in 90% ethanol. Paratypes: One specimen NCPOR /HYD–CIR/0049 from the same locality as the holotype. Ecological note: The specimen was collected along with three types of deep-sea corals, two types of brittle stars, shrimps, dead Gastropod shells, and Isopods from a basalt rocky bottom. Coloration: The yellow-orange base colour of the body. Distribution: Seamount is located near the Edmond vent field, Central Indian Ridge (CIR), in a depth range of 1981–2033 meters. Etymology: The species name “ parvatee ” is a Hindi word given based on its habitat i.e., seamount. parvatee means belong to the mountain. Description: The carapace (without rostrum) is approximately 1.34 times as long as broad. Frontal margins are tilted. Lateral margins are feebly convex, each with three to six prominent spines; small anterolateral spine; one or two spines on the anterior branchial margin; one to three spines on the posterior branchial margin (spine on the lateral base of posterior cervical groove strongest; posterior one or two spines usually reduced); scale-like tubercles and short ridges present among spines; especially on posterior branchial margin. Posterior margin ridged, and tubercles laterally. Dorsal surface with regions clearly defined; covered with numerous tubercles; tubercles fairly scale-like on posterior branchial region; conical on anterior branchial; cardiac and gastric regions. Six pairs of strong spines are present along the dorsal midline: three pairs of spines in the gastric region; two pairs of spines in the cardiac region (each in the anterior and posterior cardiac region); and one pair of very small spines on the intestinal region (Figure 2A). The gastric region is somewhat eminent. The cervical groove is different (Figures 2 & 3). Rostrum distinctly elongate; flat; and dagger-shaped; 0.5 times as long as the remaining carapace length; 4 times longer than broad; narrow; horizontal; dorsal surface covered with rugae (fine serrations); weakly depressed proximally (Figures 3A). Eyestalk movable. Cornea oval; globular; cupped in the anterolateral end of the ocular peduncle. Ocular peduncle without eye spine; reaching proximal 0.2 of the rostrum (Figures 3A). The pterygostomial flaps with broad tubercles on the lateral surface; anterior end blunt (Figure 3B). Abdominal tergites unarmed; tergites 2 and 3 each with two transverse ridges medially connected and laterally separated by deep grooves; lateral part of dorsal surfaces smooth (Figures 3H). Sternal plastron longer than broad (Figure 3D). Sternite 3 is 1.5 times broader than long; divided into two parts by a median groove; anterior margin serrated; with acute anterolateral spines. Sternite 4 three times broader than long; anterolateral surface depressed and sloping anteriorly. Sternites 5–7 medially grooved; separated from one another with elevated; transverse ridges (Figure 3D). Antennal peduncle stout; reaching at least proximal half of rostrum. Article 1 immovable; with a short distomesial spine. Article 2; article 3; and article 4 unarmed (Figure 3A). Antennular peduncle with basal article longer than broad; distal margin armed with strong ventrolateral and dorsolateral (rarely with affiliated spine) spines; lateral face inflated; ventral surface with short rugae (Figure 3C). Third maxilliped stout; ischium slightly longer than broad; approximately 0.5 times merus length; distoflexor corner acute; crista dentata well developed. Merus longer than broad; extensor margin rugose; flexor margin with small median spines and strong proximal process (divided into two spines); ventral surface with rugae. Carpus short; unarmed. Propodus with distoflexor margin convex (Figure 3F&G). Telson is composed of eight separate plates; covered with scale-like tubercles (Figure 3G). P1 subequal; distinctly elongate; 5 times PCL; each segment covered with numerous scale-like tubercles longitudinally arranged on surfaces and margins and bearing fine setae. Ischium with strong dorsodistal spine; ventrodistal margin anteriorly produced. Merus approximately 1.8 times PCL; distal margin with strong dorsal; mesial; ventral; and lateral spines; dorsodistal spine followed by a row of spines; distomesial spine strongest; followed by two or three slender spines; ventrodistal spine followed by two or three spines (usually on proximal half) along the midline of the ventral surface. Carpus approximately 0.6 times merus length; distal margin with strong dorsal; mesial and lateral spines; dorsodistal spine followed by spines and pointed tubercles; distomesial spine occasionally followed by few spines. Palm is relatively compressed; approximately 0.6 times merus length; 5 times as long as broad; mesial margin with a row of small spines or pointed tubercles. Fingers 0.5 times palm length; slightly spooned distally; occlusal margins straight and denticulate; bearing fringe of simple setae; with several triangular teeth on a movable finger (Figure 4A–D). P2 –4 slender, sparsely setose; P2 approximately 2.2 times PCL; falling short of distal margin of P1 merus; lateral surfaces of Ischia; meri; carpi; propodi covered with scale-like tubercles. Meri compressed; subequal in breadth but decreasing in length posteriorly; P2 merus approximately 0.8 times of PCL and 5 times as long as broad; P3 merus 1-time P2 merus length; P4 merus 0.7 times P2 merus length; extensor margin tuberculate; armed with a strong distal spine; flexor margin tuberculate; without a distinct spine. Carpi subequal in length; approximately 0.5 times P2 merus length; extensor surface with two longitudinal ridges each covered with scale-like tubercles and armed with a distinct distal spine; spine on mesial ridge much more prominent; flexor margin unarmed. Propodi subcylindrical; subequal in length and breadth; approximately 1-time P2 merus length and 6.5 times as long as broad; extensor margin with scale-like tubercles; flexor margin with four or five movable corneous spines on distal half; including distal pair. Dactyli slender; narrowing distally; approximately 0.5 times propodus length; flexor margin straight; with 12 or 13 movable corneous spines (spines on median part much larger) on the entire length; and distal spine closely appressed to claw; each corneous spine located on elevated base (Figure 4E). Pereopods without epipod. Egg diameter 2 mm (Figure 2D). Remarks: The new species from CIR is the closest to Munidopsis guochuani Dong, Gan & Li, 2021 known from the seamount on the Caroline Plate, West Pacific Ocean. The new species from CIR can be differentiated from M. guochuani by carapace posterior margin ridged, with a row of spines on median part and tubercles laterally (Dong et al. 2021, Figure 21A), without a row of spines on median part (Figure 3A), the shape of the sternite 3 and 4 in the sternal plastron, and seven distinct plates in telson. Genetic data. DNA sequencing for this species was successful for mtCOI gene (Accession numbers: COI: OP311614). The average K2P distance between the closely related M. guochuani (MT901058) and the CIR specimen was 0.07% for COI.Published as part of Periasamy, Rengaiyan, Kurian, Palayil John & Ingole, Baban, 2023, Two new deep-water species of squat lobsters (Crustacea: Anomura: Galatheoidea) from the Central and Southwest Indian Ridge, pp. 165-178 in Zootaxa 5231 (2) on pages 167-170, DOI: 10.11646/zootaxa.5231.2.3, http://zenodo.org/record/757527
Identification of a novel smooth muscle myosin heavy chain cDNA: isoform diversity in the S1 head region
No full textSmooth muscle myosin heavy chain (SMHC) isoforms, SM1 and SM2, are the products of alternative splicing from a single gene (P. Babij and M. Periasamy. J. Mol. Biol. 210: 673-679, 1989). We have previously shown that this splicing occurs at the 3'-end of the mRNA, resulting in proteins that differ at the carboxyterminal (R. Nagai, M. Kuro-o, P. Babij, and M. Periasamy. J. Biol. Chem. 264: 9734-9737, 1989). In the present study we demonstrate that additional SMHC isoform diversity occurs in the globular head region by isolating and characterizing two distinct rat SMHC cDNA (SMHC-11 = SM1B and SMHC-5 = SM1A). Sequence comparison of the two clones reveals that they are completely identical in their coding regions, except at the region encoding the 25/50 kDa junction of the myosin head, where the SM1B isoform contains an additional seven amino acids. This divergent region is located adjacent to the Mg(2+)-ATPase site, and differences in this region may be of functional importance. Ribonuclease protection analysis demonstrates that the corresponding SM1B and SM1A mRNA messages are coexpressed in all smooth muscle tissues; however, the proportion of the two mRNA present differs significantly between tissues. The SM1A-type mRNA predominates in most smooth muscle tissues, with the exception of intestine and urinary bladder, which contain greater proportions of the SM1B message. The differential distribution of these two isoforms may provide important clues toward understanding differences in smooth muscle contractile properties.</jats:p
Typhlonida milindi Periasamy & Kurian & Ingole 2023, sp. nov.
No full text<i>Typhlonida milindi</i> sp. nov. <p>Figs 5–7</p> <p> <b>Material examined:</b> Female holotype: NCPOR /HYD-CIR/0048, ♀ (CL 8.6 mm, PCL 3.2 mm), Seamount of the Southwest Indian Ridge, Indian Ocean, <i>R / V</i> ‘ <i>MGS Sagar’</i> cruise MGS35 (Station No: MGS35C–BD5A), 02 April 2020, 26° 21′ 10.8′′ S, 67° 41′ 27.6′′ E, 2070 to 2404 m, Benthic Sledge, Coll. Periasamy R, samples in 90% ethanol.</p> <p> <b>Ecological note:</b> The specimen was collected along with associated benthic communities of deep-sea fish, glass sponge, and coral in the ferromanganese (Fe–Mn) covered basalt rocky with a thickness of 2–4 cm.</p> <p> <b>Distribution:</b> <i>Typhlonida milindi</i> <b>sp. nov.</b> is known for its type locality in the seamount of the SWIR.</p> <p> <b>Etymology</b>: It is named in honor of our senior scientific colleague <i> — <i>Late Dr. Milind Wakadikar</i>,</i> who contributed diligently to accomplish the objectives of the Indian deep-sea mission, especially the deepsea hydrothermal exploration program.</p> <p> <b>Description:</b> Moderately small species, carapace as long as the width. Dorsal surface with main transverse ridges, without secondary transverse striae between main ridges, and striae lined with short; non-iridescent setae. Epigastric region with 2 pairs of spines, without a median row of spines behind the rostrum. Cervical groove deep; a hepatic region without spines on the dorsal surface. The anterior part of the branchial region between the cervical groove and post-cervical groove with 2 or 3 short tuberculate ridges and often 1 small spine anteriorly, posterior part of the branchial region with 5 transverse ridges excluding posterodorsal ridge. The cardiac region with 2 main transverse ridges. An intestinal region without striae; posterodorsal ridge distinct; without secondary stria. Front margin oblique; inclined posteriorly at 115° from the midline. Lateral margin slightly convex; anterolateral spine very small; far from reaching sinus between rostrum and supraocular spine; 5 spines branchial lateral or margin (Figure 6A).</p> <p> <b>Rostrum</b> spiniform; 0.6× PCL; supraocular spine 0.26× length of the rostrum; exceeding eyes. Epistomial ridge straight ending at antennal gland, mesial protuberance different (Figure 6A).</p> <p> <b>Abdominal tergites</b> unarmed; one transverse continuous stria on the second abdominal segment; without striae from the third to fifth segments.</p> <p> <b>Thoracic sternum</b> sternal surface smooth; sternite 4 with only a few striae. Sternite 3 0.3× width of sternite 4. Sternite 4 anterior margin triangular; narrowly contiguous with sternite 3. Mid-length of the sternal plastron (sternites 4–7) 0.5× width of sternite 7 (Figure 6E).</p> <p> <b>Eye</b> very small eyes; maximum corneal diameter 0.18× distance between anterolateral spines (Figure 6A).</p> <p> <b>Antenna peduncle</b> article 1 distomesial spine almost reaching the distal margin of article 2. Article 2 distomesial spine reaching distal margin of article 3; distolateral spine not reaching midlength of article 3. Articles 3 and 4 unarmed (Figure 6B).</p> <p> <b>Antennule peduncle</b> basal article (distal spines excluded) overreaching corneae; distolateral spine much longer than distomesial spine; 2 lateral spines, proximal smaller; longer lateral spine not reaching the end of distolateral spines (Figure 6C).</p> <p> <b>Third maxilliped</b> surface smooth; ischium with a small distal spine on extensor margin; ischium as long as merus length. Merus with small median spine; carpus; propodus and dactylus unarmed (Figure 6D).</p> <p> <b>Telson</b> with few striae; greatest width 1.2× median length; anterolateral margin weakly concave (Figure 6F).</p> <p> <b>P1</b> length 2.4–3.2× PCL; covered in rows of short plumose setae. Merus length 0.9–1.1× PCL; with a row of 2 large spines and 2 small spines on dorsal margin; 1 strong spine on dorsolateral margin; 4 spines on mesial margin; distomesial spine not reaching midlength of the carpus. Carpus length 0.5× merus; length 3× width, with 6 spines along the mesial margin. Propodus 1.3× merus length; palm with a row of 3 or 4 spines on the dorsal surface of the palm; fingers 0.4–0.5× total propodus length; without spines on outer margins (Figure 7).</p> <p> <b>P2–4</b> long and slender; with few small scales on lateral sides of meri and carpi; extensor margin with short plumose setae and few longer setae. P2 1.8–2.3× PCL; merus 0.7–0.8×PCL; length 8× width; 3.0× carpus length; 1.5× propodus length; extensor margin with 5–7 spines; flexor margin with 3 spines; well-developed distal spine; carpus extensor margin with the spine at midlength and a distal end; flexor margin with distal spine; propodus length about 8×height; with 5 movable flexor spines on flexor margin; dactylus gently curved distally; 0.6–0.7× propodus length, length about 7× height, extensor margin densely lined with stiff short setae on distal half; flexor margin armed along the entire length with 10–12 movable spines including spine at the base of unguis (Figure 7F). The end of P2 carpus does not reach the end of P1 merus. P3 with similar spination and article proportions as P2; merus 0.9× P2 merus length; propodus; and dactylus as long as those of P2. P4 length 0.7–0.8× P2 length, merus length 0.3–0.5× PCL; propodus and dactylus similar in length to those of P3; merocarpal articulation reaching hepatic marginal spine carapace (Figure 7).</p> <p> <b>Colour in life:</b> carapace pink anteriorly fading to white at posterior; abdominal somite 2 white; somites 3–6 pink, P1 and P2–4 white.</p> <p> <b>Genetic data:</b> DNA sequencing for this species was successful for mtCOI gene (Accession numbers: COI: OP311615). The average K2P distance between the morphologically closest <i>Typhlonida tiresias</i> (AY351014) and the SWIR specimen was 0.04% for COI.</p> <p> <b>Remarks:</b> The SWIR new species is the closest relative of <i>Typhlonida tiresias</i> (Macpherson, 1994) and <i>T. parvioculata</i> (Baba, 1982). The new species from SWIR can be differentiated from <i>Typhlonida tiresias</i> by gastric region with a row of epigastric spines, extensor border of merus of the third maxilliped, and the shape of the sternite 3. While <i>T. parvioculata</i> has a second abdominal segment with 2 to 4 spines anteriorly, a third maxilliped merus elongates with 2 prominent inner marginal spines of subequal size: one distal and another proximal to midlength and not in <i>Typhlonida milindi</i> <b>sp. nov.</b></p>Published as part of <i>Periasamy, Rengaiyan, Kurian, Palayil John & Ingole, Baban, 2023, Two new deep-water species of squat lobsters (Crustacea: Anomura: Galatheoidea) from the Central and Southwest Indian Ridge, pp. 165-178 in Zootaxa 5231 (2)</i> on pages 171-175, DOI: 10.11646/zootaxa.5231.2.3, <a href="http://zenodo.org/record/7575272">http://zenodo.org/record/7575272</a>
Shot-noise limited detection sensitivity in multiplex CARS microscopy
No full textIn multiplex CARS microscopy the generated anti-Stokes signal is generated and detected simultaneously over a significant part of the vibrational spectrum. The signal-to-noise ratio of the thus detected spectra is limited only by shot-noise. This principle is demonstrated using a dilution series of 2-propanol in water. It is derived theoretically and shown experimentally that for low solute concentrations - in contrast to methods that suppress the non-resonant background - the CARS signal strength from a particular vibrational mode depends linearly on its concentration. Furthermore, excellent agreement is shown between the experimental data and fits to the theory. It is shown that this approach permits rapid (20 ms acquisition) detection of a single lipid mono-layer, with sufficient signal-to-noise to determine the order parameter for the acyl chain packing. Also it is demonstrated that this detection scheme provides an absolute measure of the solute concentration.Radiation Chemistry DepartmentApplied Science
Synthesis of copper-platinum nanoparticles induce apoptosis in THP-1 cells
No full textBimetallic nanoparticles are considered as next generation materials with synergistic optical, electrical and catalytic properties. They are composed of two different metals and exhibit superior performance as compared to their monometallic nanoparticles. In this present study we have developed a green synthetic route for the synthesis of Cu@Pt, using polyphenol as reducing, as well as functionalizing agent. The morphological and compositional properties of the synthesized Cu@Pt nanoparticles were analyzed by high-resolution transmission electron microscopy and energy dispersive X-ray spectrometer. The electron microscopic images indicate that spherical Cu@Pt aggregates with ∼ 30 nm size are formed. The cell viability assay revealed that Cu@Pt inhibit cell proliferation and enhances nuclear morphological changes, including cell shrinkage, intranucleosomal DNA fragmentation and chromatin condensation in THP-1 cells. Our findings confirm that Cu@Pt nanoparticles can open up new opportunities for cancer therapeutic applications
Intermolecular electron transfer rate in diffusion limited region: picosecond fluorescence studies
No full textThe temporal profiles of the quenched fluorescence decay of the free base meso-tetraphenyl porphyrin (H2TPP) and its Zn derivative (ZnTPP) with quenchers such as quinones and m-dinitrobenzene have been analysed by methods developed for short time regimes which are known to be diffusion influenced [N. Periasamy et al., J. Chem. Phys.88, 1638 (1988); 89, 4799 (1988); Chem. Phys. Lett.160, 457 (1989); N. Periasamy, Biophys. J.. 54, 961 (1988); R. Das and N. Periasamy, Chem. Phys. 136, 361 (1989); G.C. Joshi et al., J. Phys. Chem.94, 2908 (1990)]. These quenchers are known to participate in an electron transfer reaction leading to a charge separation. The intrinsic rate constant (ka) derived from the analysis is examined as a function of the change in free energy in the electron transfer reaction. Such a comparison indicates that ka can be related to the electron transfer rate, ket. The electron transfer rates measured in acetonitrile (solvent reorganization energy, λs=1.35) and toluene (λs=0.1) do not indicate the existence of an inverted region as predicted by Marcus. The trend agrees with the findings of Rehm and Weller [Isr. J. Chem.8, 259 (1970)], except that the rate constants are at least one order of magnitude larger than the diffusion limited values
Rotational dynamics of surface probes in lipid vesicles
No full textTranslational and rotational diffusion of fluorescent molecules on the surface of small biological systems such as vesicles, proteins and micelles depolarize the fluorescence. A recent study has treated the case of the translational dynamics of surface probes (M. M. G. Krishna, R. Das, N. Periasamy and R. Nityananda, J. Chem. Phys., 112 (2000) 8502-8514) using Monte Carlo and theoretical methods. Here we extend the application of the methodologies to apply the case of rotational dynamics of surface probes. The corresponding fluorescence anisotropy decays were obtained using the Monte Carlo simulation methods for the two cases: surface probes undergoing rotational dynamics on a plane and on a sphere. The results were consistent with the theoretical equations which show that Monte Carlo methods can be used to simulate the surface diffusion problems. The anisotropy decay for the rotational diffusion of a molecule on a planar surface is single exponential and the residual anisotropy is zero. However, residual anisotropy is finite for the case of rotational diffusion on a sphere because of the spatial averaging of the anisotropy function. The rotational correlation time in both the cases is (4Drot)-1 with Drot being the rotational diffusion coefficient. Rotational dynamics of a surface bound dye in a single giant liposome and in sonicated vesicles were studied and the results were explained according to the theoretical equations. A fast component of fluorescence depolarization was also observed for sonicated vesicles which was interpreted as wobbling-in-cylinder dynamics of the surface-bound dye
THE REGULATION OF CALCIUM CYCLING IN STRESSED HEARTS
No full textMyothermal measurements of tension-independent heat are used to calculate the quantity of calcium released during isometric contraction and the rate at which it is removed in control, thyrotoxic and pressure-overloaded rabbit hearts. Experiments were carried out at 30-degrees-C. In control rabbit hearts 41.0 +/- 7.0 nmoles/g Ca++ was released into the cytosol for each beat, while the rate at which the Ca++ was removed from the cytosol was 24.4 +/- 4.4 nmoles/g sec. In the pressure-overloaded preparations, the amount of calcium released and the rate of calcium removal were 41% and 40% of control values. This reduction was correlated with the mRNA levels for the sarcoplasmic reticulum (SR) Ca++ ATPase, phospholamban and the ryanodine receptor. The depression was also correlated with a reduction in SR Ca++ ATPase protein expression. In thyrotoxic hearts compared with controls, with each activation there is an increase in the amount of calcium liberated into the cytosol (39%) and the rate of calcium removal (31%). This increase is correlated with an increase in the mRNA and protein expression for the SR Ca++ ATPase as well as the mRNA for the ryanodine receptor. Calsequestrin mRNA was unchanged in all of the experimental preparations. It is suggested that the alteration in the calcium cycling proteins offers at least a partial explanation for the changes in calcium cycling measured in response to the stresses applied. The coordinate nature of the myocardial plasticity as the heart remodels itself in response to the hemodynamic and endocrine stress applied is further supported by the inverse correlation between the changes in the cycled calcium, as well as the changes in calcium cycling proteins and the average cross-bridge force-time integral
THE REGULATION OF CALCIUM CYCLING IN STRESSED HEARTS
No full textMyothermal measurements of tension-independent heat are used to calculate the quantity of calcium released during isometric contraction and the rate at which it is removed in control, thyrotoxic and pressure-overloaded rabbit hearts. Experiments were carried out at 30-degrees-C. In control rabbit hearts 41.0 +/- 7.0 nmoles/g Ca++ was released into the cytosol for each beat, while the rate at which the Ca++ was removed from the cytosol was 24.4 +/- 4.4 nmoles/g sec. In the pressure-overloaded preparations, the amount of calcium released and the rate of calcium removal were 41% and 40% of control values. This reduction was correlated with the mRNA levels for the sarcoplasmic reticulum (SR) Ca++ ATPase, phospholamban and the ryanodine receptor. The depression was also correlated with a reduction in SR Ca++ ATPase protein expression. In thyrotoxic hearts compared with controls, with each activation there is an increase in the amount of calcium liberated into the cytosol (39%) and the rate of calcium removal (31%). This increase is correlated with an increase in the mRNA and protein expression for the SR Ca++ ATPase as well as the mRNA for the ryanodine receptor. Calsequestrin mRNA was unchanged in all of the experimental preparations. It is suggested that the alteration in the calcium cycling proteins offers at least a partial explanation for the changes in calcium cycling measured in response to the stresses applied. The coordinate nature of the myocardial plasticity as the heart remodels itself in response to the hemodynamic and endocrine stress applied is further supported by the inverse correlation between the changes in the cycled calcium, as well as the changes in calcium cycling proteins and the average cross-bridge force-time integral
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