Surface Dwelling Research Articles

Divergence of soil microarthropod (Hexapoda: Collembola) recovery patterns during natural regeneration and regeneration by planting of windthrown pine forests

Windthrows are natural disturbances that influence the functioning and structure of forest ecosystems and the belowground components of an ecosystem. Soil processes such as the recycling of organic matter, energy and nutrients are controlled by soil fauna. However, little is still known about the post-disturbance recovery of soil microarthropod communities in forest stands exposed to windthrow of various severity and post-windthrow forest management over time. This study assessed soil Collembola community recovery in pine forest stands over the long-term (between 9 and 14 years after the disturbance event). We predicted that (1) different severity of windthrow disturbance in a pine forest has different effects on the recovery of Collembola community composition and functional structure, even after 10 years; (2) The recovery of Collembola communities is similar during regeneration of a forest disturbed by windthrow and in a pine plantation planted after clearing of a windthrown forest and subsequent soil preparation; (3) The changes in the Collembola community during forest regeneration after windthrow disturbance can be explained by selected environmental variables, especially the leaf area index LAI. As expected, regeneration processes within forest stands shifted the species composition of collembolan communities and changed their functional structure. The surface dwelling collembolan species (epigeic and atmobiotic life form) responded to regeneration processes mainly in pine stands, especially in a pine plantation established after a clearing of broken pines and subsequent soil preparation. Our results suggest different sensitivity of collembolan communities to environmental changes induced by various degrees of opening of the tree canopy by windthrow and to those caused by the post disturbance treatment. These findings confirm that collembolan community composition recovery is slow and divergent during natural regeneration of pine stands and regeneration by planting but does not differ between moderately and severely successional trajectories. Our results also confirm the importance of canopy closure for the possibility of Collembola community regeneration. If canopies were more closed (higher leaf area index, LAI index), the possibility of regeneration increased, especially in the young pine plantations, as seen in the final years of our study.

Maternal genetic effects in Astyanax cavefish development

The role of maternal factors in the evolution of development is poorly understood. Here we describe the use of reciprocal hybridization between the surface dwelling (surface fish, SF) and cave dwelling (cavefish, CF) morphs of the teleost Astyanax mexicanus to investigate the roles of maternal genetic effects in cavefish development. Reciprocal hybridization, a procedure in which F1 hybrids are generated by fertilizing SF eggs with CF sperm (SF × CF hybrids) and CF eggs with SF sperm (CF × SF hybrids), revealed that the CF degenerative eye phenotype showed maternal genetic effects. The eyes of CF × SF hybrids resembled the degenerate eyes of CF in showing ventral reduction of the retina and corresponding displacement of the lens within the optic cup, a smaller lens and eyeball, more lens apoptosis, a smaller cartilaginous sclera, and lens-specific gene expression characteristics compared to SF × CF hybrids, which showed eye and lens gene expression phenotypes resembling SF. In contrast, reciprocal hybridization failed to support roles for maternal genetic effects in the CF regressive pigmentation phenotype or in CF constructive changes related to enhanced jaw development. Maternal transcripts encoded by the pou2f1b, runx2b, and axin1 genes, which are involved in determining ventral embryonic fates, were increased in unfertilized CF eggs. In contrast, maternal mRNAs encoded by the ß-catenin and syntabulin genes, which control dorsal embryonic fates, showed similar expression levels in unfertilized SF and CF eggs. Furthermore, maternal transcripts of a sonic hedgehog gene were detected in SF and CF eggs and early cleaving embryos. This study reveals that CF eye degeneration is controlled by changes in maternal factors produced during oogenesis and introduces A. mexicanus as a model system for studying the role of maternal changes in the evolution of development.

Developmental evolution and developmental plasticity of the olfactory epithelium and olfactory skills in Mexican cavefish

The fish Astyanax mexicanus comes in two forms: the normal surface-dwelling (SF) and the blind depigmented cave-adapted (CF) morphs. Among many phenotypic differences, cavefish show enhanced olfactory sensitivity to detect amino-acid odors and they possess large olfactory sensory organs. Here, we questioned the relationship between the size of the olfactory organ and olfactory capacities. Comparing olfactory detection abilities of CF, SF and F1 hybrids with various olfactory epithelium (OE) sizes in behavioral tests, we concluded that OE size is not the only factor involved. Other possibilities were envisaged. First, olfactory behavior was tested in SF raised in the dark or after embryonic lens ablation, which leads to eye degeneration and mimics the CF condition. Both absence of visual function and absence of visual organs improved the SF olfactory detection capacities, without affecting the size of their OE. This suggested that developmental plasticity occurs between the visual and the olfactory modalities, and can be recruited in SF after visual deprivation. Second, the development of the olfactory epithelium was compared in SF and CF in their first month of life. Proliferation, cell death, neuronal lifespan, and olfactory progenitor cell cycling properties were identical in the two morphs. By contrast, the proportions of the three main olfactory sensory neurons subtypes (ciliated, microvillous and crypt) in their OE differed. OMP-positive ciliated neurons were more represented in SF, TRPC2-positive microvillous neurons were proportionately more abundant in CF, and S100-positive crypt cells were found in equal densities in the two morphs. Thus, general proliferative properties of olfactory progenitors are identical but neurogenic properties differ and lead to variations in the neuronal composition of the OE in SF and CF. Together, these experiments suggest that there are at least two components in the evolution of cavefish olfactory skills: (1) one part of eye-dependent developmental phenotypic plasticity, which does not depend on the size of the olfactory organ, and (2) one part of developmental evolution of the OE, which may stem from embryonic specification of olfactory neurons progenitor pools.

Physical properties of the tunic in the pinkish-brown salp Pegea confoederata (Tunicata: Thaliacea)

BackgroundInvisibility in the water column is a crucial strategy for gelatinous zooplanktons in avoiding detection by visual predators, especially for animals distributed in the euphotic zone during the daytime; i.e., surface dwellers that do not undergo diel vertical migration. Salps, a member of the subphylum Tunicata (Urochordata), usually have a transparent body that is entirely covered with a cellulosic matrix, called the tunic. Some non-migrator species are known to exhibit a nano-scale nipple array on the tunic surface. However, the physical properties of the salp tunic has been poorly investigated, except for Thetys vagina, in which the tunic was expected to show low reflectance based on the refractive index of the tunic. Pegea confoederata is a non-vertical migrant salp showing pinkish-brown body. We measured the hardness, water content, absorption spectra, and refractive index of its tunic to evaluate its fragility and visibility.ResultsThere are nipple-like protuberances about 80 nm high on the surface of the tunic in P. confoederata. The tunic is very soft; the maximum force to pierce the tunic with a steel rod (1 mm diameter) was < 1 N. The water content of the tunic was > 95%. The absorption spectra of the tunic had no prominent peaks in the wavelength range of 280–800 nm, indicating the tunic is nearly transparent. The difference in refractive indices between tunic and seawater was estimated as 0.002–0.015 at 589 nm. Rigorous coupled wave analyses (RCWA) of light reflection based on 3-dimensional models supported an anti-reflective effect of the nipple array on the tunic surface, which was estimated to vary slightly depending on the forms and the arrangement patterns of nipple-like protuberances in an array.ConclusionsThe tunic of P. confoederata is very soft and contains more water than those of sessile tunicates (ascidians). Based on the refractive index of the tunic, light reflection is expected to be very low, making this salp’s tunic barely visible in water column. Our results suggest that the nipple array may produce an anti-reflective effect.

The Influence of Pressure on the Activity of Enzymes from Deep‐sea Extremophiles

Protein splicing is a post‐translational process facilitated by an intervening polypeptide, or intein. We studied inteins that interrupt the DNA Polymerase II from three different extremophiles, H. salinarum (Hsa), Pyrococcus abyssi (Pab), and Pyrococcus horikoshii (Pho). Intriguingly, all three of these inteins splice conditionally based on environmental cues. We hypothesized that since deep‐sea extremophiles such as P. abyssi and P. horikoshii live under moderately high pressures (150–200 atm), splicing will be unaffected or perhaps even enhanced under pressure. We also hypothesized that inteins from surface dwelling extremophiles like Hsa will not function as efficiently at moderate pressure. Lastly, we hypothesized high pressure (2000 atm and above), regardless of the native environment, will destabilize, unfold, and inactivate the activity. Results suggest that moderate pressures (200 atm and below) do not affect the splicing efficiency of inteins from either deep‐sea extremophile. While similarly unaffected at moderate pressure (100 atm), the function of Hsa inteins appear to be significantly diminished by higher pressures (1000 atm and above). In contrast, higher pressures appear to have no negative effect on the splicing of inteins from the deep‐seas extremophiles, and in some cases can even increase the splicing efficiency.Support or Funding InformationThis work was supported by the National Science Foundation (grant MCB‐1517138) (KVM), the Camille &amp; Henry Dreyfus Foundation, and by Kim and Wendell P. Weeks P15 to the Holy Cross Alumni/Parent Summer Research Scholarship Fund (CKR).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Nanoscale characterization of dynamic cellular viscoelasticity by atomic force microscopy with varying measurement parameters.

Cell mechanics plays an important role in regulating the physiological activities of cells. The advent of atomic force microscopy (AFM) provides a novel powerful instrument for quantifying the mechanics of single cells at the nanoscale. The applications of AFM in single-cell mechanical assays in the past decade have significantly contributed to the field of cell and molecular biology. However, current AFM-based cellular mechanical studies are commonly carried out with fixed measurement parameters, which provides limited information about the dynamic cellular mechanical behaviors in response to the variable external stimuli. In this work, we utilized AFM to investigate cellular viscoelasticity (portrayed as relaxation time) with varying measurement parameters, including ramp rate and surface dwell time, on both cell lines and primary cells. The experimental results show that the obtained cellular relaxation times are remarkably dependent on the parameter surface dwell time and ramp rate during measurements. Besides, the dependencies to the measurement parameters are variable for different types of cells, which can be potentially used to indicate cell states. The research improves our understanding of single-cell dynamic rheology and provides a novel idea for discriminating different types of cells by AFM-based cellular viscoelastic assays with varying measurement parameters.

Deciphering the State of the Late Miocene to Early Pliocene Equatorial Pacific

AbstractThe late Miocene‐early Pliocene was a time of global cooling and the development of modern meridional thermal gradients. Equatorial Pacific sea surface conditions potentially played an important role in this global climate transition, but their evolution is poorly understood. Here we present the first continuous late Miocene‐early Pliocene (8.0–4.4 Ma) planktic foraminiferal stable isotope records from eastern equatorial Pacific Integrated Ocean Drilling Program Site U1338, with a new astrochronology spanning 8.0–3.5 Ma. Mg/Ca analyses on surface dwelling foraminifera Trilobatus sacculifer from carefully selected samples suggest that mean sea surface temperatures (SSTs) are ~27.8 ± 1.1°C (1σ) between 6.4 and 5.5 Ma. The planktic foraminiferal δ18O record implies a 2°C cooling between 7.2 and 6.1 Ma and an up to 3°C warming between 6.1 and 4.4 Ma, consistent with observed tropical alkenone paleo‐SSTs. Diverging fine‐fraction‐to‐foraminiferal δ13C gradients likely suggest increased upwelling between 7.1–6.0 and 5.8–4.6 Ma, concurrent with the globally recognized late Miocene Biogenic Bloom. This study shows that both warm and asymmetric mean states occurred in the equatorial Pacific during the late Miocene‐early Pliocene. Between 8.0–6.5 and 5.2–4.4 Ma, low east‐west δ18O and SST gradients and generally warm conditions prevailed. However, an asymmetric mean climate state developed between 6.5 and 5.7 Ma, with larger east‐west δ18O and SST gradients and eastern equatorial Pacific cooling. The asymmetric mean state suggests stronger trade winds developed, driven by increased meridional thermal gradients associated with global cooling and declining atmospheric pCO2 concentrations. These oscillations in equatorial Pacific mean state are reinforced by Antarctic cryosphere expansion and related changes in oceanic gateways (e.g., Central American Seaway/Indonesian Throughflow restriction).

Vital Effects and Ecologic Adaptation of Photosymbiont‐Bearing Planktonic Foraminifera During the Paleocene‐Eocene Thermal Maximum, Implications for Paleoclimate

AbstractStable isotope‐size data of four major planktonic foraminifera lineages from the Paleocene‐Eocene Thermal Maximum (PETM, ~56 Ma) at two locations (North Atlantic New Jersey shelf and Southern Ocean) are analyzed. By comparing changes in δ13C/δ18O‐size correlation prior to and during the PETM, we present evidence of significant changes in vital effects in photosymbiont‐bearing planktonic foraminifera during the PETM. The δ13C‐size data indicate divergent changes in δ13C vital effects in high‐latitude versus mid‐latitude populations, due likely to different responses in photosymbiotic activities. Combined δ18O‐size data and isotopic ranking indicates that some surface dwellers experienced changes that may be interpreted as depth migrations. Extreme temperatures (&gt;32°C) may have exerted selective pressure and drove depth migrations. Species with flexible depth distribution were capable of adapting to rapid warming by vertical migration in the upper ocean, while populations restricted to near‐surface ocean may have undergone temporal and/or regional collapse during the peak warming. From a paleo‐proxy perspective, these biologic responses have the potential to obscure paleoceanographic signatures both regionally and globally.

Stable isotope analysis of micronekton around Hawaii reveals suspended particles are an important nutritional source in the lower mesopelagic and upper bathypelagic zones

AbstractSeveral studies have found that the respiratory demand for carbon by the mesopelagic community exceeds carbon supply through the particulate sinking flux by up to two to three orders of magnitude, suggesting that mesopelagic communities rely on additional overlooked carbon sources. Suspended particles (defined as 0.7–53 μm) have been suggested as one of these sources but few studies have evaluated their contribution to the mesopelagic food web. We use amino acid compound‐specific nitrogen isotope analysis to investigate whether suspended particles are an important nutritional source to fish, cephalopod, and crustacean micronekton species in the central North Pacific. Our results suggest that micronekton feed from food webs fueled by a variety of nutritional sources including surface dwelling phytoplankton and bacteria, sinking particles, and suspended particles, with micronekton becoming more reliant on suspended particles with increasing habitat depth. Several species were identified as feeding from a primarily suspended particle‐based food web including the fishes Cyema atrum, Cyclothone pallida, Melanocetus johnsonii, Serrivomer sector, and the pelagic octopod Japetella diaphana. We also found that micronekton species feeding from a suspended particle food web cannot be identified using bulk tissue δ15N values. Our data support the notion that suspended particles are an important nutritional source in the lower mesopelagic and upper bathypelagic and they should be accounted for when estimating carbon supply for these communities.

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Badger (Meles meles) disturbances affect oribatid mite (Acari: Oribatida) communities in European temperate forests

Burrowing mammals living in forests are one of the important disturbance factors driving changes in species community and diversity on the forest floor. In the present study we examined the impact of soil mounds created by badgers (Meles meles) on species richness and the community structure of oribatid mites, which constitute one of the most numerous components of soil mesofauna. We compare oribatid communities between forest soils disturbed by badgers in 1-year-old mounds and 5-year-old mounds as well as undisturbed forest soil to get an insight into the direction of temporal changes. The study plots were situated in pine forests within the Kampinos Forest (Poland). The soil parameters created by badgers and ecological groups in the oribatid fauna were analysed. The results showed that distinct oribatid communities occur in badger mounds when compared with adjacent undisturbed forest soil. It appeared that badgers have the potential to substantially affect the soil environment in forest ecosystems and finally influenced mite abundance and community composition. Initial badger disturbance caused a significant decline in the abundance and biodiversity of oribatid mites, but within a few years the oribatid fauna was restored. Our results supported the intermediate disturbance hypothesis. Badger activity affected the composition of ecological groups of mites, toward surface dwelling, primary decomposers and sexually reproducing species. It can be concluded that badger mounds serve as microhabitats for some soil mites and contribute to the patchiness and heterogeneity of the forest floor. Finally, oribatid community structure proved to be a good indicator of soil disturbance caused by mammal activities involving deep digging in soil and heaping mounds in temperate forests.

Influence of the bulk diffusion of rubidium and sodium atoms in glass on their surface dwell time

This paper presents the results of measurement of the surface potential and the dwell time of Rb and Na atoms on the surface of S-52 molybdenum glass. It is found that at temperatures below the glass transition temperature, the temperature dependence of the dwell time of Rb atoms is well described by the Arrhenius formula. The surface potentials for Rb and Na are measured to be 0.67 and 1.37 eV, respectively. At temperatures above the glass transition temperature, the dwell time of these atoms increases abnormally. The reason for this is that during impact of an atom on the surface of molten glass, it can penetrate into the volume of the window and then return by diffusion and desorb from the surface. In this case, the dwell time of the atom on the glass is determined by the diffusion time and can be very significant, despite the relatively low potential barrier at the surface and high temperature.

Rock Art, Architecture, and Social Groups at the Basketmaker III–Pueblo I Transition: Evidence from the Procession Panel, Southeast Utah

This paper draws on iconographic style, social psychology research, and architectural evidence to suggest that the Procession Panel on Comb Ridge, southeast Utah, provides an accurate depiction of the households within an early Mesa Verde community ca. A.D. 760–800. It argues that the Procession Panel depicts a community in transition, when some households began to reorganize as members of lineages and materialized this relationship by constructing large, multihousehold surface dwellings. However, not all households organized into lineage-scale groups, and these differences between these two kinds of social organization created fault lines where social inequalities could later develop.

Diversity and dynamics of potentially toxic cyanobacteria and their public health significance in lake Koto Barombi, Cameroon

Bloom–forming freshwater cyanobacteria pose human and livestock health problems due to their ability to produce toxins and other bioactive compounds. Some non-toxic cyanobacteria accumulate as buoyant surface dwelling scums and thick mats which affect the benthic fauna by degrading aquatic habitats and giving negative aesthetic values to the water body. They cause taste and odour problems by producing bioactive compounds. The diversity and succession of bloom-forming nostocales in surface waters were determined monthly in Lake Koto Barombi in Cameroon using light microscopy. Physico-chemical analyses of the water were also carried out. Three prominent genera encountered were Cylindrospermopsis, Anabaena, and Aphanizomenon. Microcystis flos-aquae were also found in high numbers. There was a positive correlation between potentially toxic and bloom-forming nostocales and a negative correlation between potentially toxic nostocales and nitrates. Water temperature was an important driving force for their succession. Potentially toxic nostocales and ‘other potentially toxic cyanobacteria’ accounted for 54% of the phytoplankton population in August and 57% in October in some stations but the general concentration of phytoplankton was low. The concentration of nostocales present in January and November 2013 were higher than the WHO guidelines for safe water for recreation. The results of semi-structured questionnaires revealed high prevalence of gastrointestinal disease during periods of algal blooms.Key words: Cyanobacteria, cyanoHAB, potentially toxic nostocales, dynamics, harmful, algae, public health, scums

The lateral line confers evolutionarily derived sleep loss in the Mexican cavefish.

Sleep is an essential behavior exhibited by nearly all animals, and disruption of this process is associated with an array of physiological and behavioral deficits. Sleep is defined by changes in sensory gating that reduce sensory input to the brain, but little is known about the neural basis for interactions between sleep and sensory processing. Blind Mexican cavefish comprise an extant surface dwelling form and 29 cave morphs that have independently evolved increased numbers of mechanoreceptive lateral line neuromasts and convergent evolution of sleep loss. Ablation of the lateral line enhanced sleep in the Pachón cavefish population, suggesting that heightened sensory input underlies evolutionarily derived sleep loss. Targeted lateral line ablation and behavioral analysis localized the wake-promoting neuromasts in Pachón cavefish to superficial neuromasts of the trunk and cranial regions. Strikingly, lateral line ablation did not affect sleep in four other cavefish populations, suggesting that distinct neural mechanisms regulate the evolution of sleep loss in independently derived cavefish populations. Cavefish are subject to seasonal changes in food availability, raising the possibility that sensory modulation of sleep is influenced by metabolic state. We found that starvation promotes sleep in Pachón cavefish, and is not enhanced by lateral line ablation, suggesting that functional interactions occur between sensory and metabolic regulation of sleep. Taken together, these findings support a model where sensory processing contributes to evolutionarily derived changes in sleep that are modulated in accordance with food availability.

Hydrographic and ecologic implications of foraminiferal stable isotopic response across the U.S. mid‐Atlantic continental shelf during the Paleocene‐Eocene Thermal Maximum

AbstractWe present new δ13C and δ18O records of surface (MorozovellaandAcarinina) and thermocline dwelling (Subbotina) planktonic foraminifera and benthic foraminifera (Gavelinella,Cibicidoides, andAnomalinoides) during the Paleocene‐Eocene Thermal Maximum (PETM) from Millville, New Jersey, and compare them with three other sites located along a paleoshelf transect from the U.S. mid‐Atlantic coastal plain. Our analyses show different isotopic responses during the PETM in surface versus thermocline and benthic species. Whereas all taxa record a 3.6–4.0‰ δ13C decrease associated with the carbon isotope excursion, thermocline dwellers and benthic foraminifera show larger δ18O decreases compared to surface dwellers. We consider two scenarios that can explain the observed isotopic records: (1) a change in the water column structure and (2) a change in habitat or calcification season of the surface dwellers due to environmental stress (e.g., warming, ocean acidification, surface freshening, and/or eutrophication). In the first scenario, persistent warming during the PETM would have propagated heat into deeper layers and created a more homogenous water column with a thicker warm mixed layer and deeper, more gradual thermocline. We attribute the hydrographic change to decreased meridional thermal gradients, consistent with models that predict polar amplification. The second scenario assumes that environmental change was greater in the mixed layer forcing surface dwellers to descend into thermocline waters as a refuge or restrict their calcification to the colder seasons. Although both scenarios are plausible, similar δ13C responses recorded in surface, thermocline, and benthic foraminifera challenge mixed layer taxa migration.

Feeding Ecology of Brook Silverside, Golden Shiner, and Subyearling Pumpkinseed in a Lake Ontario Embayment

Abstract Fish feeding ecology has been shown to vary over a 24-h period in terms of the prey consumed and feeding intensity. Consequently, in order to best determine the interspecific feeding associations within a fish community, examination of the diet at multiple times over a 24-h period is often necessary. We examined the diel feeding ecology of three fish species that were numerically dominant in a Lake Ontario embayment during summer. The diet of each of the three species, young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus, was distinct with no significant overlap in diet composition occurring within any of the 4-h time intervals. The diet composition of each species suggested that Brook Silverside were feeding at the surface (terrestrial invertebrates and aquatic surface dwelling hemipterans), whereas young-of-year Pumpkinseed (amphipods) and Golden Shiner (tipulids) were feeding on different benthic prey. Differences in feeding periodicity were most pronounced for young-of-year Pumpkinseed. Our findings provide valuable insights on interspecific feeding associations among these three fish species during summer in a Lake Ontario embayment.

Swim and fly: escape strategy in neustonic and planktonic copepods.

Copepods can respond to predators by powerful escape jumps that in some surface-dwelling forms may propel the copepod out of the water. We studied the kinematics and energetics of submerged and out-of-water jumps of two neustonic pontellid copepods, Anomalocera patersoni and Pontella mediterranea, and one pelagic calanoid copepod, Calanus helgolandicus (euxinus). We show that jumping out of the water does not happen just by inertia gained during the copepod's acceleration underwater, but also requires the force generated by the thoracic limbs when breaking through the water's surface to overcome surface tension, drag and gravity. The timing of this appears to be necessary for success. At the moment of breaking the water interface, the instantaneous velocity of the two pontellids reached 125 cm s-1, while their maximum underwater speed (115 cm s-1) was close to that of similarly sized C. helgolandicus (106 cm s-1). The average specific power produced by the two pontellids during out-of-water jumps (1700-3300 W kg-1 muscle mass) was close to that during submerged jumps (900-1600Wkg-1 muscle mass) and, in turn, similar to that produced during submerged jumps of C. helgolandicus (1300 W kg-1 muscle mass). The pontellids may shake off water adhering to their body by repeated strokes of the limbs during flight, which leads to a slight acceleration in the air. Our observations suggest that out-of-water jumps of pontellids are not dependent on any exceptional ability to perform this behavior but have the same energetic cost and are based on the same kinematic patterns and contractive capabilities of muscles as those of copepods swimming submerged.

Daily and Seasonal Expression Profile of Serum Melatonin and Its Biosynthesizing Enzyme Genes (tph1, aanat1, aanat2, andhiomt) in Pineal Organ and Retina: A Study under Natural Environmental Conditions in a Tropical Carp,Catla catla

The tropical carp Catla catla is gaining importance for the studies of the impact of environmental changes on aquatic animals due to its surface dwelling habitat. To date, no information is available on the transcriptional profile of melatonin biosynthesizing enzyme genes in any tropical carp under either natural or artificial photothermal conditions in pineal and retina. The present study is an attempt to demonstrate the temporal pattern of expression of melatonin biosynthesizing enzyme genes, tryptophan hydroxylase 1 (tph1), arylalkylamine N-acetyltransferase (aanat1 and aanat2), and hydroxyindole-O-methyltransferase (hiomt) collectively and simultaneously in pineal organ and retina in tropical fish, C. catla, on a daily and seasonal basis under natural environmental conditions along with the serum melatonin levels. Depending upon the changes of the natural photothermal conditions, in four phases of an annual cycle, the variation and/or shifting of the rhythm parameters of different melatonin biosynthesizing enzyme genes in these two organs are different. Moreover, relative expression of these genes varies based on tissue and season. The serum melatonin levels correspond to the expression pattern of pineal aanat2 and hiomt. This finding indicates a possible organization of melatonin biosynthesizing enzyme genes with reproductive phases differently in these two photoreceptive organs for maintaining its physiological functions.

Cloning, phylogenetic analysis and tissue distribution of melatonin bio-synthesizing enzyme genes (Tph1, Aanat1, Aanat2 and Hiomt) in a tropical carp, Catla catla

The surface dwelling tropical carp Catla catla is gaining importance as a model for the study on the impact of ever-changing aquatic environment as well as chronobiology. Melatonin is the only chronobiotic molecule and act as the neurohormonal messenger in the synchronization of environmental stimuli and the body physiology. Therefore, the sequence analysis of the major enzymes involved in the bio-synthesis of this indole amine is the prime requisite. The present study is an attempt to clone the full-length sequences of melatonin biosynthesising enzyme genes, Tryptophan hydroxylase 1 (Tph1), Arylalkylamine N-acetyltransferase (Aanat1 and Aanat2) and Hydroxyindole-O-methyltransferase (Hiomt) in any tropical fish. This study has identified two subtypes of Aanat (1 &2) as it was found in other teleost. The distribution of these enzymes were found in nine tissues (brain, pineal organ, retina, gut, liver, skeletal muscle, heart, kidney and ovary) which include both central and peripheral units. This finding is signifying the presence of melatonin bio-synthesizing machinery in all major tissues/organs of this tropical carp. High sequence similarities of these genes among teleost revealed a conserved pattern of evolution and the presence of melatonin bio-synthesising enzyme gene transcripts in all major tissues makes it a prominent candidate to be used as model for the chronobiological studies.