Jaishri Menon - Academia.edu (original) (raw)

Papers by Jaishri Menon

Journal of Biological Chemistry, 1992

We have been investigating the role of proteolytic enzymes in the inactivation of peptide neurotr... more We have been investigating the role of proteolytic enzymes in the inactivation of peptide neurotransmitters in the marine snail Aplysia. Previous studies (Squire, C. R., Talebian, M., Menon, J. G., Dekruyff, S. D., Lee, T. D., Shively, J. E., and Rothman, B. S. (1991) J. Biol. Chem. 266, 22355-22363) showed that neuroactive fragments of the neurotransmitter alpha-bag cell peptide (alpha-BCP) were rapidly degraded (t1/2 = 0.5-2.7 min) in plasma, hemolymph that had been cleared by centrifugation. Degradation was caused by one or more enzymes resembling mammalian leucine amino-peptidase (LAP, EC 3.4.11.1). In this report we show that three other Aplysia peptide neurotransmitters, beta-BCP(1-5) (Arg-Leu-Arg-Phe-His), FMRFa (Phe-Met-Arg-Phe-amide), and SCPB(1-9) (Met-Asn-Tyr-Leu-Ala-Phe-Pro-Arg-Met-amide) are rapidly degraded (t1/2 = 0.3-2.4 min) in plasma by apparently the same LAP-like enzyme(s). Our findings strongly suggest that the LAP-like enzyme(s), by means of its broad substrate specificity and access to the extracellular spaces of the nervous system in vivo, plays a significant role in the inactivation of many Aplysia peptide neurotransmitters, and they raise the possibility that proteolytic enzymes in the extracellular fluid contribute significantly to the inactivation of peptide neurotransmitters in other animal species.

Journal of Neurobiology, 1992

Alpha‐bag cell peptide [α‐BCP (Ala‐Pro‐Arg‐Leu‐Arg‐Phe‐Tyr‐Ser‐Leu)] is a neurotransmitter that m... more Alpha‐bag cell peptide [α‐BCP (Ala‐Pro‐Arg‐Leu‐Arg‐Phe‐Tyr‐Ser‐Leu)] is a neurotransmitter that mediates bag cell‐induced inhibition of left‐upper‐quadrant (LUQ) neurons L2, L3, L4, and L6 in the abdominal ganglion of Aplysia. Our recent biochemical studies have shown that α‐BCP[1–9] is cleaved into α‐BCP[1–2], [3–9], [1–5], [6–9], and [7–9] by a combination of three distinct peptidase activities located within the extracellular spaces of the CNS: A diaminopeptidase‐IV (DAP‐IV)‐like enzyme cleaves α‐BCP[1–9] at the 2–3 peptide bond; a neutral metalloendopeptidase (NEP)‐like enzyme cleaves either α‐BCP[1–9] or α‐BCP[3–9] at the 5–6 bond; an aminopeptidase M‐II (APM‐II)‐like enzyme cleaves α‐BCP[6–9] at the 6–7 bond, but cleaves neither α‐BCP[1–9], nor the other ganglionic peptidase products. To further understand the manner in which α‐BCP is inactivated after release, that is loses its electro‐physiological activity, we studied its structure‐activity relationship by recording intrace...

APS March Meeting Abstracts, Mar 1, 2014

Applied Sciences, 2019

Atmospheric pressure plasma has found wide clinical applications including wound healing, tissue ... more Atmospheric pressure plasma has found wide clinical applications including wound healing, tissue regeneration, sterilization, and cancer treatment. Here, we have investigated its effect on developmental processes like metamorphosis and tail regeneration in tadpoles. Plasma exposure hastens the process of tail regeneration but delays metamorphic development. The observed differences in these two developmental processes following plasma exposure are indicative of physiological costs associated with developmental plasticity for their survival. Ultrastructural changes in epidermis and mitochondria in response to the stress of tail amputation and plasma exposure show characteristics of cellular hypoxia and oxidative stress. Mitochondria show morphological changes such as swelling with wide and fewer cristae and seem to undergo processes such as fission and fusion. Complex interactions between calcium, peroxisomes, mitochondria and their pore transition pathways are responsible for change...

The European Physical Journal Special Topics, 2017

Abstract Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged p... more Abstract Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged particles, including electrons and ions, as well as reactive oxygen species (ROS). Recently, it is utilized as possible therapy in oncology, sterilization, skin diseases, wound healing and tissue regeneration. In this study we focused on effect of plasma exposure on tail regeneration of tadpoles, Xenopus leavis with special emphasis on role of ROS, antioxidant defenses and morphological features of the regenerate. When amputated region of the tail was exposed to the helium plasma it resulted in a faster rate of growth, elevated ROS and increase in antioxidant enzymes in the regenerate compared to that of untreated control. An increase in nitric oxide (free radical) as well as activity of nitric oxide synthase(s) were observed once the cells of the regeneration blastema – a mass of proliferating cells are ready for differentiation. Microscopically the cells of the regenerate of plasma treated tadpoles show altered morphology and characteristics of cellular hypoxia and oxidative stress. We summarize that plasma exposure accelerates the dynamics of wound healing and tail regeneration through its effects on cell proliferation and differentiation as well as angiogenesis mediated through ROS signaling.

Healthy wounds require a balanced combination of nutrients and growth factors for healing and tis... more Healthy wounds require a balanced combination of nutrients and growth factors for healing and tissue regeneration. Nitric oxide, (NO), is also crucial in wound healing processes and linked with production of several cytokines, interaction with other free radicals and influence on microcirculation. Hypothesize is that exposure to plasma will affect wound healing and tail regeneration in tadpoles Xenopus laevis and plasma induced endogenous NO production may have an important role to play at the cellular level. Tail amputation was immediately followed by exposure of the wound to the helium plasma. For histological features, blastema (growing regenerate) was fixed in 4% neutral buffer formalin for paraffin sections. In situ staining for NO was carried out 5 days post amputation. The rate of the regenerating tail was proportional to the plasma exposure time at the expense of metamorphic rate. Histological features show that the tadpoles exposed to the plasma had a higher level of cellul...

Journal of Experimental Biology, 2009

SUMMARY Evolutionary transitions between different environmental media such as air and water pose... more SUMMARY Evolutionary transitions between different environmental media such as air and water pose special problems with respect to skin permeability because of the dramatic changes in the driving gradients and nature of water exchange processes. Also, during the transitional periods prior to complete adaptation to a new medium, the skin is exposed to two very different sets of environmental conditions. Here, we report new data for transepidermal evaporative water loss (TEWL) and cutaneous resistance to evaporative water loss (Rs) of sea snakes that are transitional in the sense of being amphibious and semi-terrestrial. We investigated three species of sea kraits (Elapidae: Laticaudinae) that are common to Orchid Island (Lanyu),Taiwan. Generally, Rs of all three species is lower than that characteristic of terrestrial/xeric species of snakes measured in other taxa. Within Laticauda, Rs is significantly greater (TEWL lower) in the more terrestrial species and lowest (TEWL highest)in t...

Journal of Morphology, 1992

... JAISHRI G. MENON AND ALISSA J . ARP Department of Biology, Sun Francisco State Uniuersity, Su... more ... JAISHRI G. MENON AND ALISSA J . ARP Department of Biology, Sun Francisco State Uniuersity, Sun Francisco, California 94132 ... and sulfide levels may reach as high as 25 to 30 pM, a level toxic to most organisms (National Research Council, 1979; Hansen, 1989; Arp et al ...

Journal of Morphology, 2000

The effects of external Ca(++) on metamorphosis of Rana catesbeiana tadpoles were assessed. Treat... more The effects of external Ca(++) on metamorphosis of Rana catesbeiana tadpoles were assessed. Treatment of tadpoles with Ca(++) (0.05 mM) during early prometamorphic stages induced precocious metamorphic events such as tail regression, shortening of the intestine, forelimb emergence, and keratinization of body epidermis within 23 days of treatment compared to control tadpoles still in mid-prometamorphic stages. These effects of Ca(++) are probably mediated by the thyroid gland, as indicated by histological features of the gland at the light and electron microscopic levels. Calcium levels of tail and body skin were measured at various stages of development by atomic absorption spectrophotometry. In control and experimental groups, body skin had significantly higher Ca(++) concentrations than tail skin. There were no statistically significant effects of developmental stage on Ca(++) levels of tail or body skin. Experimental Ca(++) treatment significantly increased Ca(++) concentration in tail but not body skin. Ultrastructure studies and gel electrophoresis indicated that calcium induced keratinization of body skin, but not tail epidermis. Ca(++)-treated tail epidermis showed various autolysing figures in apoptotic cells. In summary, calcium treatment accelerated metamorphosis and induced the following region-dependent cellular events: keratinization of body skin-a characteristic of adult epidermis-and programmed cell death in the tail. Whatever signal elicited by calcium in this experimentally induced accelerated metamorphosis is probably mediated via the thyroid gland.

Invertebrate Biology, 1998

Invertebrate Biology, 2005

... Jaishri Menon,a Julia K. Willsie, Andrew Tauscher, and Alissa J. Arpb ... Note interdigitatio... more ... Jaishri Menon,a Julia K. Willsie, Andrew Tauscher, and Alissa J. Arpb ... Note interdigitation of cell membranes (small arrowheads), cytoplasm filled with electron-dense organelles (EDOs: largewhite arrows), abundant glycogen (G) in cytoplasm, and zonula adherens (ZA). ...

Integrative and Comparative Biology, 1995

American Zoologist, 2000

The avian epidermis is composed of unique sebokeratinocytes that elaborate and secrete sebum-like... more The avian epidermis is composed of unique sebokeratinocytes that elaborate and secrete sebum-like lipids as they cornify. In addition to the lipid droplets, the avian epidermis elaborates, but rarely secretes, lipid-enriched organelles, the multigranular bodies. The multigranular bodies are analogous to the lamellar bodies of mammals (Menon et al., 1991), the secretion of which results in formation of occlusive lipid bilayers characteristic of mammalian stratum corneum and providing the permeability barrier. However, in contrast to mammals, the avian multigranular bodies form the reserve barrier mechanism. In the basal state, when multigranular bodies are not secreted, the avian cutaneous barrier is deficient, but allows evaporative cooling for thermoregulation. However, under conditions of water deficit, multigranular body secretion allows for rapid facultative waterproofing, as shown in zebra finches (Taenyopygia guttata). In certain glabrous regions of the skin, such as the maxillary rictus, interdigital web, and combs and wattles in the domestic fowl, there is a high degree of epidermal lipid secretion. Also specialized feathers such as powder downs elaborate lipid rich material, which can be classified as secretion. Additionally, an inverse relation between epidermal lipogenesis and the degree of feathering has been demonstrated, as in temporarily bare areas (e.g., brood patches) and following permanent feather loss from the head accompanying attainment of maturity in certain ibises and storks. In the latter, the neo-apteria often hold large reserves of carotenoids dissolved in the lipid droplets, possibly related to an altered gradient of retinoids influencing feather morphogenesis. Unusual secondary functions of epidermal lipids include cosmetic coloration (e.g., in the Japanese Crested Ibis) and chemical defense (e.g., in the Pitohui).

In Vitro Cellular & Developmental Biology - Animal, 2001

In Vitro Cellular & Developmental Biology - Animal, 1999

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2007

Anuran metamorphosis is characterized by rapid and drastic changes in the body form and function ... more Anuran metamorphosis is characterized by rapid and drastic changes in the body form and function under the influence of thyroid hormones. We evaluated the involvement of reactive oxygen species and antioxidant defenses during intestinal remodeling and tail regression of tadpoles of Xenopus laevis. Oxidative stress resulting from depletion in catalase and reduced glutathione, and simultaneous increase in lipid peroxidation during intestinal remodeling as well as tail regression are probably responsible for cell death and differentiation in these organs. Gene expression data for superoxide dismutase and catalase supports this contention. A dramatic increase in another antioxidant, ascorbic acid content of both these organs during metamorphic climax indicates its multifactor role such as collagen synthesis in intestine and controlled tail regression. These findings suggest that the cellular environment in the intestine and tail becomes progressively more oxidizing during its remodeling and regression respectively.

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2013

Tail regression in tadpoles is one of the most spectacular events in anuran metamorphosis. Reacti... more Tail regression in tadpoles is one of the most spectacular events in anuran metamorphosis. Reactive oxygen species and oxidative stress play an important role during this process. Presently, the cell-and tissue-specific localization of antioxidant enzymes such as superoxide dismutase (SOD) and catalase as well as neuronal and inducible nitric oxide synthase isoforms (nNOS and iNOS) responsible for production of nitric oxide (NO) were carried out during different stages of metamorphosis in tail of tadpole Xenopus laevis. NO also has profound effect on the mitochondrial function having its own nitric oxide NOS enzyme. Hence, in situ staining for NO and mitochondria also was investigated. The distribution of nNOS and iNOS was found to be stage specific, and the gene expression of nNOS was up-regulated by thyroxin treatment. In situ staining for NO and mitochondria shows co-localization, suggesting mitochondria being one of the sources of NO. SOD and catalase showed significant co-localization during earlier stages of metamorphosis, but before the tail regression begins, there was a significant decrease in activity as well as co-localization suggesting increased ROS accumulation. These findings are discussed in terms of putative functional importance of ROS and cytoplasmic as well as mitochondrial derived NO in programmed cell death in tail tissue.

The Biological Bulletin, 1993

During low tide, the burrow water of the marine echiuran worm Urechis caupo becomes hypoxic, and ... more During low tide, the burrow water of the marine echiuran worm Urechis caupo becomes hypoxic, and hydrogen sulfide concentrations reach levels that would be toxic to most animals. Integument morphology in U. caupo is evaluated as an exchange surface and as a permeation barrier. Adaptive features include the rugose nature of the epidermis, which increases the surface area for oxygen uptake, and the thick muscular body wall, which provides a chief motive power in creating peristaltic movements along the body wall to ventilate the burrow. The epidermis is covered by a cuticle and contains two types of mucus-secreting cells: orthochromatic and metachromatic. Underlying connective tissue and three muscle layers form the bulk of the body wall. The integument does not present a significant structural barrier to permeation, although the mucus secreted by the epidermal cells may retard sulfide entry. Ultrastructural studies suggest three possible mechanisms that U. caupo may use to counteract the toxic effects of sulfide at the integumentary surface: metabolism of symbiotic bacteria embedded in the innermost cuticle layer and grouped together in the superficial epidermis, dying off of peripheral, sulfide-exposed cells, and oxidation of sulfide at specialized, ironrich, lysosomal organelles termed sulfide oxidizing bodies.

$Research paper thumbnail of The Effect of Plasma on Tail Regeneration of Tadpoles \textit{Xenopus Laevis}$

Bulletin of the American Physical Society, 2013

ABSTRACT Healthy wounds require a balanced combination of nutrients and growth factors for healin... more ABSTRACT Healthy wounds require a balanced combination of nutrients and growth factors for healing and tissue regeneration. Nitric oxide, (NO), is also crucial in wound healing processes and linked with production of several cytokines, interaction with other free radicals and influence on microcirculation. Hypothesize is that exposure to plasma will affect wound healing and tail regeneration in tadpoles Xenopus laevis and plasma induced endogenous NO production may have an important role to play at the cellular level. Tail amputation was immediately followed by exposure of the wound to the helium plasma. For histological features, blastema (growing regenerate) was fixed in 4% neutral buffer formalin for paraffin sections. In situ staining for NO was carried out 5 days post amputation. The rate of the regenerating tail was proportional to the plasma exposure time at the expense of metamorphic rate. Histological features show that the tadpoles exposed to the plasma had a higher level of cellular proliferation and microvasculature in blastema. In situ staining for NO indicated its increased endogenous production compared to the control. These findings suggest that accelerated wound healing and tail regeneration following exposure to the plasma may be due to its direct effect on cell proliferation and increased NO production which may be involved in microvascularization.