Papers by DHANASEKAR KRISHNAMOORTHY
This study documents the cascade of events that occurred in the coast and biota of the Chennai re... more This study documents the cascade of events that occurred in the coast and biota of the Chennai region exposed to an accidental oil spill near the Ennore port after the collision of two cargo ships. The impact of the collision was so severe that the oil compartment was damaged, spilling approximately 22 tonnes of oil at initial hours. Due to waves, tidal action and southern current, the spillage travelled a long distance up to a stretch of around 52 km along the coastline in Bay of Bengal. Damage to the biota was monitored at different zones based on the intensity of the oil spill to evaluate the environmental impact caused by it. The shorelines of most of these areas had shown signs of oil sludge deposited in the sediments and boulders from the very next day of the collision. An intensive survey indicated that the sea turtles, crabs, fishes and seaweeds were washed ashore that posed a threat to the coastal habitat. Further, in-depth, histological studies on gills, hepatopancreas and...
Revista Derecho Administrativo Económico, 2021
El artículo analiza el proyecto de ley chileno que establece el derecho a la portabilidad o migra... more El artículo analiza el proyecto de ley chileno que establece el derecho a la portabilidad o migración eléctrica: esto es, el derecho de los usuarios finales del sistema de distribución a elegir a su suministrador de energía, mediante la separación del negocio de las redes de distribución del de la comercialización de la energía eléctrica, un proyecto con que el legislador busca, en último término, reducir el poder monopólico de las distribuidoras de electricidad.
The present study document the cryopreservation of sperm different was experimented with a variet... more The present study document the cryopreservation of sperm different was experimented with a variety of cryoprotectants for short term storage. Cryoprotectants toxicity assay on sperm clearly indicated that 15% DMSO + glycerol. yielded maximum motility (86.19±4.92 %) and viability (72.53± 2.01 %), at 15min equilibration time. However, other cryoprotectants such as DMF + glycerol resulted in low percentage of sperm viability and motility. The results clearly document that 15% DMSO + glycerol with HBSS extender at dilution ratio 1:10 at --196º C, proved to be suitable for cryopreservation of Poecilia sphenops sperm.
Animal reproduction science, 2018
Ultrastructure and development of spermatozoa in cobia, Rachycentron canadum are described. Secti... more Ultrastructure and development of spermatozoa in cobia, Rachycentron canadum are described. Sections through the testis show different developmental stages viz, Spermatocytes, spermatids and sperm. Spermatozoa of R. canadum exhibit the configuration of uniflagellated, anacrosomal Type I aquasperm, typical for externally fertilizing fish. Mature spermatozoon is seen with a prominent head and long cylindrical flagellum. Ultrastructure of sperm shows invaginated 'U' shaped nucleus and other organelles. The mitochondrial matrix is electron-dense with irregular arrangement of the cristae. The nucleus reveals a deep invagination (nuclear fossa) in which the centriolar complex is located. The centriolar complex lies inside the nuclear fossa and is composed of a proximal and a distal centriole. The two centrioles are placed perpendicular to each other. The flagellum has a typical eukaryotic organization (microtubule doublets 9 + 2 pattern) and measures around 36.21 ± 0.42 μm in leng...
Proceedings of the Zoological Society, 2017
Ultrastructure of spermatozoa in fairy shrimp Streptocephalus dichotomus revealed that they are a... more Ultrastructure of spermatozoa in fairy shrimp Streptocephalus dichotomus revealed that they are amoeboid type with no acrosome and flagella. Surface topography of the spermatozoon is smooth with occasional pseudopodial projections. Transmission electron micrographs of spermatozoa show organelle and the mitochondria which is not fused to form the so called 'Nebenkern'. The testicular lumen reveals spermatozoa in varying sizes and shapes.
Journal of the Marine Biological Association of India, 2016
Distribution of heavy metals and its associated structural and biochemical perturbations were stu... more Distribution of heavy metals and its associated structural and biochemical perturbations were studied in the tissues of lobster Panulirus homarus homarus collected from Royapuram harbour which receives effluents from various industries located in northern coast of Chennai and compared with that of the less polluted Kovalam coast. The concentrations of copper, zinc, iron and cadmium were quantified in gills, muscles, hepatopancreas and gonadal tissues. The results showed marked differences between the two sites as well as significant variations were observed between the tissues. Metal accumulation was seen in the order of Cu> Zn >Fe>Cd in lobsters collected from Royapuram (polluted site) and Zn>Cu>Fe>Cd from Kovalam (less polluted site). Overall, the highest metal concentrations were found in the lobster collected from Royapuram coast. Of various tissues, the metal accumulation was high in hepatopancreas and ovary of P. homarus homarus. Structural architecture of the tissues was further investigated by light and scanning electron microscopy. Histological studies clearly indicated degeneration and atrophy of muscle fibres, lumen disruption in hepatopancreas, conspicuously ovary showed mature oocytes without yolk granules and disruption of follicle cell in lobsters collected from Royapuram coast. However, such structural deformities were not encountered in lobsters from Kovalam. Similarly scanning electron micrograph of gill showed normal surface topography with prominent gill filaments in lobsters collected from Kovalam, whereas, gill architecture was completely disrupted in lobsters from Royapuram. This clearly reflects the impact of metal pollution on various tissues of lobsters, which may affect lobster resources in east coast of India.
Aquaculture Research, 2014
Fertilizability of cryopreserved and cadaveric fish spermatozoa was attempted in the freshwater c... more Fertilizability of cryopreserved and cadaveric fish spermatozoa was attempted in the freshwater catfish Pangasius sutchi. Cryopreservation of spermatozoa was done with three cryoprotectants for short time storage (30 days). Whereas the spermatozoa obtained from the cadaveric fish were stored at À20°C (30 days) without any cryoprotectants. Cryoprotectant toxicity assay showed maximum motility of 88.53 AE 2.01% and viability of spermatozoa (96.19 AE 4.92%) with 15% of Dimethyl acetamide (DMA) at 15 min equilibration time. Whereas Dimethyl sulfoxide (DMSO) (15%) registered moderate level of motility and viability 79.23 AE 2.02% and 80.89 AE 2.1%, respectively. However, the methanol (MeOH) (20%) resulted in low percentage of motility (58.6 AE 0.9%) and viability (68.6 AE 0.9%). Scanning electron micrographs further showed no significant deformity on the surface topography of spermatozoa of cadaveric fish as well as cryopreserved with DMA (15%). The results indicated that 15% of DMA with hanks balanced salt solution (HBSS) extender at a dilution ratio of 1:10 at À80°C proved to be suitable for cryopreservation of spermatozoa in P. sutchi. This may be due to the osmolality of HBSS similar to seminal plasma of P. sutchi. Further studies on motility, viability and fertility potential of spermatozoa revealed 73.62 AE 1.61%, 88.34 AE 1.05% and 54 AE 2.2%, respectively, with DMA (15%). On the other hand, cadaveric fish sperm registered 57.12 AE 2.32%, 63.45 AE 0.94% and 25.33 AE 1.53% of motility, viability and fertilizability respectively. Thus, this study augments the feasibility of using cryopre-served as well as cadaveric fish spermatozoa for the seedling production in the fresh water catfish P. sutchi.
The present study evaluates the effect of formulated feeds on growth performance and colour enhan... more The present study evaluates the effect of formulated feeds on growth performance and colour enhancement in the fresh water gold fish carrassius auratus. Fishes were fed with formulated diet incorporated with different doses of leaf extract such as 0, 100, 200, 400 and 800 mg kg - 1 of diet for 45 days. Biochemical composition of skin and muscle diet D3 showed the highest activity than compared to control. Hence, carotenoid analysis showed the maximum in the D3 than compared to control. The result demonstrates that fishes fed with D3 showed highest growth parameter, biochemical and TLC than compared with the control (P<0.05). The survivability was higher in experimental animals than the control. Dietary supplementation at the level of 400 mg kg -1 showed significantly (P<0.05)
The present study documents the occurrence of an intersex condition in a natural population of mu... more The present study documents the occurrence of an intersex condition in a natural population of mullet Mugil cephalus L. On closure examination of the dissected fish, 11 females and 7 males were recorded. Histological observations through the testes indicated that one of the male fish showed different developmental stages of oocytes in between the seminiferous tubules. Interestingly, the condition reported here did not show any internal bilateral division of the reproductive system into male and female components. But it had shown the occurrence of oocytes and spermatozoa throughout the entire region of the testis of a functional male. The observation of intersex testis or testicular oocytes (TO) is of first report from the east coast of India. The fish being catadromous, this condition may be related to possible accumulation of chemical contaminants in the habitat water.
Animal Reproduction Science
This study documents the cascade of events that occurred in the coast and biota of the Chennai re... more This study documents the cascade of events that occurred in the coast and biota of the Chennai region exposed to an accidental oil spill near the Ennore port after the collision of two cargo ships. The impact of the collision was so severe that the oil compartment was damaged, spilling approximately 22 tonnes of oil at initial hours. Due to waves, tidal action and southern current, the spillage travelled a long distance up to a stretch of around 52 km along the coastline in Bay of Bengal. Damage to the biota was monitored at different zones based on the intensity of the oil spill to evaluate the environmental impact caused by it. The shorelines of most of these areas had shown signs of oil sludge deposited in the sediments and boulders from the very next day of the collision. An intensive survey indicated that the sea turtles, crabs, fishes and seaweeds were washed ashore that posed a threat to the coastal habitat. Further, in-depth, histological studies on gills, hepatopancreas and eggs of the crab Grapsus albolineatus, showed structural deformities with irregular gill tips and lower haemocytes counts in the gill samples. Whereas hepatopancreas and eggs did not show any structural deformities, although they appeared black due to adhesion of oil, but no sign of oil in the internal region. This pilot study provides baseline information about the post oil spill scenario of the coastal region as alarming and a threat to ecologically sensitive marine organisms.
The present study documents the occurrence of an intersex condition in a natural population of mu... more The present study documents the occurrence of an intersex condition in a natural population of mullet Mugil cephalus L.
On closure examination of the dissected fish, 11 females and 7 males were recorded. Histological observations through the
testes indicated that one of the male fish showed different developmental stages of oocytes in between the seminiferous
tubules. Interestingly, the condition reported here did not show any internal bilateral division of the reproductive system into
male and female components. But it had shown the occurrence of oocytes and spermatozoa throughout the entire region of the
testis of a functional male. The observation of intersex testis or testicular oocytes (TO) is of first report from the east coast of
India. The fish being catadromous, this condition may be related to possible accumulation of chemical contaminants in the
habitat water.
Ultrastructure and development of spermatozoa in cobia, Rachycentron canadum are described.
Secti... more Ultrastructure and development of spermatozoa in cobia, Rachycentron canadum are described.
Sections through the testis show different developmental stages viz, Spermatocytes, spermatids
and sperm. Spermatozoa of R. canadum exhibit the configuration of uniflagellated, anacrosomal
Type I aquasperm, typical for externally fertilizing fish. Mature spermatozoon is seen with a
prominent head and long cylindrical flagellum. Ultrastructure of sperm shows invaginated ‘U’
shaped nucleus and other organelles. The mitochondrial matrix is electron-dense with irregular
arrangement of the cristae. The nucleus reveals a deep invagination (nuclear fossa) in which the
centriolar complex is located. The centriolar complex lies inside the nuclear fossa and is composed
of a proximal and a distal centriole. The two centrioles are placed perpendicular to each
other. The flagellum has a typical eukaryotic organization (microtubule doublets 9 + 2 pattern)
and measures around 36.21 ± 0.42 μm in length. This study for the first time provides a comprehensive
detail on the ultrastructure and developmental process of sperm in cobia, R. canadum.
Ultrastructure of spermatozoa in fairy shrimp Streptocephalus dichotomus revealed that they are a... more Ultrastructure of spermatozoa in fairy shrimp Streptocephalus dichotomus revealed that they are amoe-boid type with no acrosome and flagella. Surface topography of the spermatozoon is smooth with occasional pseudopodial projections. Transmission electron micro-graphs of spermatozoa show organelle and the mitochon-dria which is not fused to form the so called 'Nebenkern'. The testicular lumen reveals spermatozoa in varying sizes and shapes.
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Papers by DHANASEKAR KRISHNAMOORTHY
On closure examination of the dissected fish, 11 females and 7 males were recorded. Histological observations through the
testes indicated that one of the male fish showed different developmental stages of oocytes in between the seminiferous
tubules. Interestingly, the condition reported here did not show any internal bilateral division of the reproductive system into
male and female components. But it had shown the occurrence of oocytes and spermatozoa throughout the entire region of the
testis of a functional male. The observation of intersex testis or testicular oocytes (TO) is of first report from the east coast of
India. The fish being catadromous, this condition may be related to possible accumulation of chemical contaminants in the
habitat water.
Sections through the testis show different developmental stages viz, Spermatocytes, spermatids
and sperm. Spermatozoa of R. canadum exhibit the configuration of uniflagellated, anacrosomal
Type I aquasperm, typical for externally fertilizing fish. Mature spermatozoon is seen with a
prominent head and long cylindrical flagellum. Ultrastructure of sperm shows invaginated ‘U’
shaped nucleus and other organelles. The mitochondrial matrix is electron-dense with irregular
arrangement of the cristae. The nucleus reveals a deep invagination (nuclear fossa) in which the
centriolar complex is located. The centriolar complex lies inside the nuclear fossa and is composed
of a proximal and a distal centriole. The two centrioles are placed perpendicular to each
other. The flagellum has a typical eukaryotic organization (microtubule doublets 9 + 2 pattern)
and measures around 36.21 ± 0.42 μm in length. This study for the first time provides a comprehensive
detail on the ultrastructure and developmental process of sperm in cobia, R. canadum.
On closure examination of the dissected fish, 11 females and 7 males were recorded. Histological observations through the
testes indicated that one of the male fish showed different developmental stages of oocytes in between the seminiferous
tubules. Interestingly, the condition reported here did not show any internal bilateral division of the reproductive system into
male and female components. But it had shown the occurrence of oocytes and spermatozoa throughout the entire region of the
testis of a functional male. The observation of intersex testis or testicular oocytes (TO) is of first report from the east coast of
India. The fish being catadromous, this condition may be related to possible accumulation of chemical contaminants in the
habitat water.
Sections through the testis show different developmental stages viz, Spermatocytes, spermatids
and sperm. Spermatozoa of R. canadum exhibit the configuration of uniflagellated, anacrosomal
Type I aquasperm, typical for externally fertilizing fish. Mature spermatozoon is seen with a
prominent head and long cylindrical flagellum. Ultrastructure of sperm shows invaginated ‘U’
shaped nucleus and other organelles. The mitochondrial matrix is electron-dense with irregular
arrangement of the cristae. The nucleus reveals a deep invagination (nuclear fossa) in which the
centriolar complex is located. The centriolar complex lies inside the nuclear fossa and is composed
of a proximal and a distal centriole. The two centrioles are placed perpendicular to each
other. The flagellum has a typical eukaryotic organization (microtubule doublets 9 + 2 pattern)
and measures around 36.21 ± 0.42 μm in length. This study for the first time provides a comprehensive
detail on the ultrastructure and developmental process of sperm in cobia, R. canadum.