Mechanistic understanding on the uptake of micro-nano plastics by plants and its phytoremediation.

Contaminated soil is one of today's most difficult environmental issues, posing serious hazards to human health and the environment. Contaminants, particularly micro-nano plastics, have become more prevalent around the world, eventually ending up in the soil. Numerous studies have been conducted to investigate the interactions of micro-nano plastics in plants and agroecosystems. However, viable remediation of micro-nano plastics in soil remains limited. In this review, a powerful in situ soil remediation technology known as phytoremediation is emphasized for addressing micro-nano-plastic contamination in soil and plants. It is based on the synergistic effects of plants and the microorganisms that live in their rhizosphere. As a result, the purpose of this review is to investigate the mechanism of micro-nano plastic (MNP) uptake by plants as well as the limitations of existing MNP removal methods. Different phytoremediation options for removing micro-nano plastics from soil are also described. Phytoremediation improvements (endophytic-bacteria, hyperaccumulator species, omics investigations, and CRISPR-Cas9) have been proposed to enhance MNP degradation in agroecosystems. Finally, the limitations and future prospects of phytoremediation strategies have been highlighted in order to provide a better understanding for effective MNP decontamination from soil.

Optimization of phytase production by Penicillium oxalicum in solid-state fermentation for potential as a feed additive.

The study aims to statistically optimize the phytase production by Penicillium oxalicum PBG30 in solid-state fermentation using wheat bran as substrate. Variables viz. pH, incubation days, MgSO4, and Tween-80 were the significant parameters identified through the Plackett-Burman design (PBD) that majorly influenced the phytase production. Further, central composite design (CCD) method of response surface methodology (RSM) defined the optimum values for these factors i.e., pH 7.0, 5 days of incubation, 0.75% of MgSO4, and 3.5% of Tween-80 that leads to maximum phytase production of 475.42 U/g DMR. Phytase production was also sustainable in flasks and trays of different sizes with phytase levels ranging from 394.95 to 475.42 U/g DMR. Enhancement in phytase production is 5.6-fold as compared to unoptimized conditions. The in-vitro dephytinization of feed showed an amelioration in the nutritive value by releasing inorganic phosphate and other nutrients in a time-dependent manner. The highest amount of inorganic phosphate (33.986 mg/g feed), reducing sugar (134.4 mg/g feed), and soluble protein (115.52 mg/g feed) was achieved at 37 °C with 200 U of phytase in 0.5 g feed for 48 h. This study reports the economical and large-scale production of phytase with applicability in enhancing feed nutrition.

Role of Oxidative Stress and Genetic Polymorphism of Matrix Metalloproteinase-2 and Tissue Inhibitor of Metalloproteinase-2 in COPD.

Chronic obstructive pulmonary disease (COPD), a complaint described by progressive and inadequately reversible limitation in lungs with systemic inflammation, is largely current in India. There's no remedy available so far it is, thus, imperative to understand the underpinning pathogenesis of the complainant. A set of proteases known as Matrix metalloproteinase (MMPs) are especially involved in the process of alveolar destruction and mucus hypersecretion. There are responsible factors in an inheritable position to control COPD like MMPs and TIMPs (Tissue Inhibitor of Metalloproteinases). MMPs degrade extracellular matrix and lead to the pathogenesis of COPD [1]. TIMPs proteins that help to inhibit the Matrix metalloproteinases. [2]. This review summarizes the implicit part of crucial MMP-2 and TIMP-2 in COPD disease. Though the concept seems promising, limited knowledge about the exact functions of a particular MMP in COPD and the complications of MMP in substrate affinity makes this a grueling task. MMP2 and TIMP2 both are directly or indirectly regulated by oxidative stress and epigenetic mechanism which regulates their expressions. COPD is a seditious response to factors like dust, smoke, etc., and triggers extra-pulmonary goods which cause inflammation. [3]. This review explains the relationship between MMP2 and TIMP2 in COPD patients with oxidative stress, its impact on COPD pathogenesis, and gene expression of TIMP2 and MMP2 with their downstream effects. This also gives some insights into therapeutic interventions for targeting these enzymes. MMP2 and TIMP2 both play a role in the development of COPD and they need to be studied with the utmost focus.

Insights into microbial diversity on plastisphere by multi-omics.

Plastic pollution is a major concern in marine environment as it takes many years to degrade and is one of the greatest threats to marine life. Plastic surface, referred to as plastisphere, provides habitat for growth and proliferation of various microorganisms. The discovery of these microbes is necessary to identify significant genes, enzymes and bioactive compounds that could help in bioremediation and other commercial applications. Conventional culture techniques have been successful in identifying few microbes from these habitats, leaving majority of them yet to be explored. As such, to recognize the vivid genetic diversity of microbes residing in plastisphere, their structure and corresponding ecological roles within the ecosystem, an emerging technique, called metagenomics has been explored. The technique is expected to provide hitherto unknown information on microbes from the plastisphere. Metagenomics along with next generation sequencing provides comprehensive knowledge on microbes residing in plastisphere that identifies novel microbes for plastic bioremediation, bioactive compounds and other potential benefits. The following review summarizes the efficiency of metagenomics and next generation sequencing technology over conventionally used methods for culturing microbes. It attempts to illustrate the workflow mechanism of metagenomics to elucidate diverse microbial profiles. Further, importance of integrated multi-omics techniques has been highlighted in discovering microbial ecology residing on plastisphere for wider applications.

Biotherapeutic microbial supplementation for ameliorating fish health: developing trends in probiotics, prebiotics, and synbiotics use in finfish aquaculture.

Nutrition demands in aquaculture can be realized through quality aquafeeds as compounded diets that contribute to the growth and health of aquaculture species. Functional additives in feed, notably probiotics, prebiotics, and their admixture synbiotics, have been recently recognized for their biotherapeutic role as immunostimulants capable of conferring disease resistance, stress tolerance, and gastrointestinal health; counteracting the negative effects of anti-nutrients, pathogenic prevalence, and antimicrobials in finfish aquaculture. Formulated diets based on probiotics, prebiotics, and as a supplemental combination for synbiotics can significantly influence fish gut microbiomes, establishing the modalities of microbial dynamics to maximize host-associated benefits. These microbial functional-feed supplements are acclaimed to be biocompatible, biodegradable, and safe for dietary consumption as well as the environment. In fed fish aquaculture, prebiotic appended probiotic diet 'synbiotic' has propounded larger attention for its additional health and nutritional benefits. Synbiotic, prebiotic, and probiotic usage as functional feeds for finfish aquaculture thus provides promising prospects. Developing trends in their intended application are reviewed here forth.

Bioaugmentation for remediation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) contaminated soil using a clay based bioformulation.

Bioaugmentation is an important remediation strategy for hazardous organic compounds. A microcosm study was conducted to evaluate the remediation of soils contaminated with hazardous high explosive, Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) using an eco-friendly bioformulation. Janibacter cremeus, an enriched indigenous soil bacterium isolated from the explosive contaminated site was immobilized in a mixture of calcite and cocopeat for bioaugmentation. The developed bioformulation showed a consistent viability for 150 days, at 4 °C storage conditions. HMX at field concentrations was degraded in microcosms for 35 days under unsaturated (aerobic) and saturated (anoxic) moisture conditions. Negligible degradation was observed under unsaturated moisture conditions, whereas, saturated conditions led to substantial decrease in HMX. Mass spectrometric (MS) analysis revealed the formation of nitroso derivatives of HMX during the anoxic degradation. Also, observed was the presence of 5-hydroxy-4-nitro-2,4-diazapentanal, a precursor of 4- nitro-2,4-diazabutanal, which eventually could be mineralized. An inexpensive and natural carrier when chosen for immobilization of explosive degrading microbes was found to be effective in the in situ remediation of explosive.

Biochemical composition, transmission and diagnosis of SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) is a life-threatening respiratory infection caused by severe acute respiratory syndrome virus (SARS-CoV-2), a novel human coronavirus. COVID-19 was declared a pandemic by World Health Organization in March 2020 for its continuous and rapid spread worldwide. Rapidly emerging COVID-19 epicenters and mutants of concerns have created mammoth chaos in healthcare sectors across the globe. With over 185 million infections and approximately 4 million deaths globally, COVID-19 continues its unchecked spread despite all mitigation measures. Until effective and affordable antiretroviral drugs are made available and the population at large is vaccinated, timely diagnosis of the infection and adoption of COVID-appropriate behavior remains major tool available to curtail the still escalating COVID-19 pandemic. This review provides an updated overview of various techniques of COVID-19 testing in human samples and also discusses, in brief, the biochemical composition and mode of transmission of the SARS-CoV-2. Technological advancement in various molecular, serological and immunological techniques including mainly the reverse-transcription polymerase chain reaction (RT-PCR), CRISPR, lateral flow assays (LFAs), and immunosensors are reviewed.

A novel egg shell-based bio formulation for remediation of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) contaminated soil.

Environmental contamination by secondary explosive has been posing threat to human health and the ecosystem. We investigated the potential of a novel bioformulation developed from poultry waste for the bioremediation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soils. Eggshells and additives immobilized with an indigenous explosive degrading microbe Janibacter cremeus were utilized for the development of the wettable powder bioformulation. Treatments carried out under unsaturated and saturated soil conditions resulted in 62 and 73 % removal of RDX respectively in 35 days meeting the soil clean up goals. The saturated treatment sets exhibited better microbial growth during the study in terms of live cell count and total enzyme activity. The bacteria, J. cremeus was observed to exhibit significant release of nitrite under both unsaturated as well as saturated conditions. Mass spectrometric studies showed that, both the conditions lead to the formation of nitroso-derivatives of RDX. But under saturated condition, an intermediate, 5-hydroxy-4-nitro-2,4-diazapentanal was observed which is a precursor to 4-nitro-2,4-diazabuatnal ultimately leading to mineralization. An accessible bio resource from poultry waste when used as a carrier for explosive degrading microbe has proven effective for in situ remediation of explosive contaminated soils.

Microbial remediation of micro-nano plastics: Current knowledge and future trends.

An alarming rise of micro-nano plastics (MNPs) in environment is currently causing the biggest threat to biotic and abiotic components around the globe. These pollutants, apart from being formed through fragmentation of larger plastic pieces and are also manufactured for commercial usage. MNPs enter agro-ecosystem, wildlife, and human body through the food chain, ingestion or through inhalation, causing blockage in the blood-brain barrier, lower fertility, and behavioural abnormalities among other problems. Hence, it becomes essential to develop novel procedures for remediation of MNPs. Among the numerous existing methods, microbial remediation promises to degrade/recover MNPs via a green route. Since microbial remediation processes mostly depend upon biotic and abiotic factors such as (temperature, pH, oxidative stress, etc.), it becomes easy to influence changes in the plastic pollutants. Hence, with the help of recent technologies, a complete degradation/removal of MNPs can be expected by utilizing the respective carbon content as energy sources for growth of microorganisms. In this review, considering the urgent environmental need, the impact of micro-nano plastics on ecosystem along with its corresponding degradation mechanisms has been brought out. Also, importance of the various recent research approaches in MNPs remediation is highlighted. Finally, the role of enzyme and membrane technology, nanoparticle technology, and metagenomics in remediation of MNPs are discussed for the first time in detail to bring out a novel remedy for the environment.

Exploring Providencia rettgeri for application to eco-friendly paper based microbial fuel cell.

We report results of the studies relating to improved stability (40 days) of small sized microbial fuel cell (MFC) fabricated using agarose embedded paper-based proton exchange membrane. A fermentative bacterium Providencia rettgeri was isolated from rotten potato slurry and identified by 16S rRNA sequencing. The electroactivity of the bacteria was monitored via chronoamperometric and cyclic voltammetric studies using a three-electrode system which indicated the presence of bacterial redox mediator. The Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) and UV-Vis absorption spectroscopy provided the evidence that Providencia rettgeri synthesized folate (vitamin B9) during fermentation that was found to act for the first time as a redox mediator in an MFC. The paper based designed MFC fed with Providencia rettgeri yielded open circuit voltage of 787.9 mV with power and current density of 5.02 W/m3 and 11.26 A/m3, respectively when measured across 10 kΩ. The microbial re-chargeable battery comprising of an assembly of parallelly aligned four units of MFCs when connected in series (total 16 MFCs), generated 1.5 V that was used for powering a red-light emitting device (LED).

Aerobic biodegradation of high explosive hexahydro-1,3,5- trinitro-1,3,5-triazine by Janibacter cremeus isolated from contaminated soil.

OBJECTIVE: To evaluate the ability of Janibacter cremeus a soil bacterium isolated from explosive contaminated site in degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and to study enzyme responsible for degradation. RESULTS: The isolate exhibited 88% degradation of RDX in 30 days of incubation. The biodegradation process followed the first order kinetics. The half- life of RDX was calculated to be 11.088 days. The RDX degradation process was complemented by concomitant release of nitrite ions with 0.78 mol of nitrite released per mole of RDX. The metabolites; Trinitroso- RDX, diamino-RDX, trimino-RDX, bis- (hydroxymethyl) nitramine and methylenedintramine derivative, viz, methylene- N- (hydroxy- methyl)- hydroxylamine- N-(hydroxymethyl) nitroamine corresponding to the molecular weights 174, 162, 132, 122 and 167 Da respectively were also detected. Nitroreductase enzyme was found to be responsible for RDX degradation. CONCLUSION: J. cremeus could degrade RDX as sole source of nitrogen, via three different pathways wherein, Nitroreductase enzyme was found to play a major role. The efficient degradation of RDX makes J. cremeus suitable in treatment of contaminated water and soil at field scale levels.

Mass Production of Lemna minor and Its Amino Acid and Fatty Acid Profiles.

The surface floating duckweed Lemna minor (Lemnaceae) is a potential ingredient to replace the application of fish-meal in the aqua-feed. The culture technique of the duckweed was standardized in outdoor tanks and then applied in the pond. Three consecutive experiments were conducted in tanks (1.2 × 0.35 × 0.3 m). In experiment 1, four different manures were used. In manure 1 (organic manure, OM) and manure 3 (2x OM), cattle manure, poultry droppings, and mustard oil cake (1:1:1) were used; in manure 2 (inorganic fertilizer, IF), urea, potash, triple superphosphate were used; manure 4 (2x OM+IF) was a combination of manure 2 and manure 3. In experiment 2, manure 1 (OM) and manure 2 (IF) were used, and manure 3 (OM+IF) was a combination of both manures. In experiment 3, OM and IF were selected. In pond (20 × 10 × 0.5 m), OM was applied. Fresh duckweed was seeded after 5 days of manure application. In experiments 1 and 3, total production was significantly (P < 0.05) higher in OM compared to other treatments. In experiment 2, there was no significant (P > 0.05) difference in production between OM and IF. In pond, relative growth rate (RGR) of duckweed ranged from 0.422 to 0.073 g/g/day and total production was 702.5 Kg/ha/month (dry weight). Protein, lipid, and ash contents were higher in duckweed cultured in OM compared to IF. The duckweed was a rich source of essential (39.20%), non-essential (53.64%), and non-proteinogenic (7.13%) amino acids. Among essential amino acids, leucine, isoleucine, and valine constituted 48.67%. Glutamic acid was 25.87% of total non-essential amino acids. Citrulline, hydroxiproline, taurine, etc. were found in the duckweed. The fatty acid composition was dominated by PUFA, 60-63% of total fatty acids, largely α-linolenic acid (LNA, 18:3n-3) at around 41 to 47% and linoleic acid (LA, 18:2n-6) at 17-18%. The nutritional value of duckweeds and their production potential in the pond conditions were evaluated. Duckweed biomass may thus be used to replace commercial fish-meal that is currently used in aquaculture.

Nanostructured zirconia decorated reduced graphene oxide based efficient biosensing platform for non-invasive oral cancer detection.

We report results of the studies relating to fabrication of a non-invasive, label-free and an efficient biosensing platform for detection of the oral cancer biomarker (CYFRA-21-1). One step hydrothermal process was used for uniform decoration of nanostructured zirconia (average particle size 13 nm) on reduced graphene oxide (ZrO2-RGO) to avoid coagulation of the zirconia nanoparticles and to obtain enhanced electrochemical performance of ZrO2-RGO nanocomposite based biosensor. Further, ZrO2-RGO has been functionalized using 3-aminopropyl triethoxy saline (APTES) and electrophoretically deposited on the indium tin oxide coated glass substrate at a low DC potential.The APTES/ZrO2-RGO/ITO electrode exhibits improved heterogeneous electron transfer (more than two times) with respect to that of the APTES/ZrO2/ITO electrode indicating faster electron transfer kinetics. The -NH2 containing APTES/ZrO2-RGO/ITO platform is further biofunctionalized with anti-CYFRA-21-1. The structural and morphological investigations of the ZrO2-RGO based biosensing platform have been accomplished using X-ray diffraction (XRD), electrochemical, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) studies. This immunosensor exhibits a wider linear detection range (2-22 ng mL(-1)), excellent sensitivity (0.756 µA mL ng(-1)) and a remarkable lower detection limit of 0.122 ng mL(-1). The observed results have been validated via enzyme linked immunosorbent assay (ELISA).

In vitro digestibility study of some plant protein sources as aquafeed for carps Labeo rohita and Cyprinus carpio using pH-Stat method.

Aquaculture, as a promising food industry, is expected to meet the demand for quality food from the increasing human population. As the diet is critical for feeding farm fish, such a faster growth in the industry is destined to create stress in the fishmeal market to supply diets to the tune. In this context, here, we studied the protein content of 20 plant ingredients, including aquatic weeds, cereals, pulses and oil-cakes using micro-Kjeldahl method and evaluated in vitro digestibility of these ingredients for rohu Labeo rohita and common carp Cyprinus carpio using pH-Stat method. The protein contents of water fern, duckweed, almond oil-cake and soybean product were 20.81, 39.75, 47.78 and 57.48%, respectively. Species-specific digestibility was found for the same plant ingredient. The degree of hydrolysis for water fern, duck weed, almond oil-cake and soybean product were 14.17, 4.80, 17.30 and 3.57%, respectively for rohu and 4.58, 6.03, 12.17 and 3.35%, respectively for common carp. This study showed that incorporation of water fern and almond oil-cake in the diet of rohu, and duck weed and almond oil-cake in the diet of common carp are beneficial considering their protein content and digestibility. These are cost-effective, protein-rich feed ingredients for aquafeed.

Biomedical and Clinical Importance of Mussel-Inspired Polymers and Materials.

The substance secreted by mussels, also known as nature's glue, is a type of liquid protein that hardens rapidly into a solid water-resistant adhesive material. While in seawater or saline conditions, mussels can adhere to all types of surfaces, sustaining its bonds via mussel adhesive proteins (MAPs), a group of proteins containing 3,4-dihydroxyphenylalanine (DOPA) and catecholic amino acid. Several aspects of this adhesion process have inspired the development of various types of synthetic materials for biomedical applications. Further, there is an urgent need to utilize biologically inspired strategies to develop new biocompatible materials for medical applications. Consequently, many researchers have recently reported bio-inspired techniques and materials that show results similar to or better than those shown by MAPs for a range of medical applications. However, the susceptibility to oxidation of 3,4-dihydroxyphenylalanine poses major challenges with regard to the practical translation of mussel adhesion. In this review, various strategies are discussed to provide an option for DOPA/metal ion chelation and to compensate for the limitations imposed by facile 3,4-dihydroxyphenylalanine autoxidation. We discuss the anti-proliferative, anti-inflammatory, anti-microbial activity, and adhesive behaviors of mussel bio-products and mussel-inspired materials (MIMs) that make them attractive for synthetic adaptation. The development of biologically inspired adhesive interfaces, bioactive mussel products, MIMs, and arising areas of research leading to biomedical applications are considered in this review.

Physiological responses of Catla catla larvae fed with Achyranthes aspera seed enriched diet and exposed to UV-B radiation.

The antioxidant and growth stimulating properties of seeds of Achyranthes aspera were evaluated on UV-B irradiated Catla catla (catla) larvae. Catla larvae (initial weight: 1.2 ± 0.01 mg) were fed with four different diets--D1, D2 and D3 containing 0.1, 0.25 and 0.5% seeds of A. aspera and D4, control diet for 35 days. The larvae were then exposed to UV-B radiation (80 µW/cm2) on every alternate day for 20 days. Survival, growth, tissue glutamic oxaloacetic transminase (GOT), tissue glutamate pyruvate transminase (GPT), thiobarbituric acid reactive substances (TBARS) and nitric oxide synthase (NOS) were studied in larvae on day-21 of irradiation. Significantly (P < 0.05) higher survival and average weight were found in D3 diet fed fish compared to the other groups. Survival rate was 8-16% higher in seed enriched diet fed groups, compared to the control one. Higher levels of GOT and GPT found in control diet fed larvae showed the degree of tissue damage due to UV-B exposure. Significantly (P < 0.05) lower level of GPT in D3 indicated the UV-B protective effect of the seed of A. Aspera (earlier, the presence of ecdysterone, essential fatty acids and amino acids, polyphenolic compounds, steroids, etc. has been reported from seed). TBARS which indicated the level of tissue lipid peroxidation were significantly (P < 0.05) higher in control group, compared to the other feeding schemes. NOS level was significantly (P < 0.05) higher in D2 and D3, compared to the D1 and control groups. In conclusion, supplementation of A. aspera seed (0.5%) improved the physiological condition (in terms of reduce lipid oxidation and better immune system) and gave bioprotection to catla larvae challenged with UV-B stress.

Simulation study of natural UV-B radiation on Catla catla and its impact on physiology, oxidative stress, Hsp 70 and DNA fragmentation.

UV-B radiation is a potential stressor to the aquacultural species. Catla catla, catla larvae (1.08±0.065g) were exposed to different doses of UV-B radiation, 0 (control), 504, 1008, 1512 and 2016mJ/cm(2) at a mean radiant energy of 80µW/cm(2) for 21days. The dose of UV-B radiation was selected on the basis of the field study conducted in Lake Naini, Delhi, India (Latitude: 28°41'26″N and Longitude: 77°12″37″E). Significantly (P<0.05) lower survival, average weight and specific growth rate were found in UV-B irradiated larvae compared to the control one. Food conversion ratio was 1.5-4-fold higher in UV-B treated larvae compared to the control one. The carbonyl protein (CP), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) levels were significantly (P <0.05) higher in UV-B irradiated larvae compared to the control group. Among the treated larvae, CP and SOD were significantly (P <0.05) higher in larvae exposed at 1512mJ/cm(2) UV-B. A correlation was found between the CP and SOD (R(2)=0.834). Highest TBARS level was found in 2016mJ/cm(2) UV-B exposed catla. Nitric oxide synthase level was significantly (P <0.05) lower in UV-B exposed larvae compared to the control one. A 3-fold increased Hsp 70 level was recorded in UV-B irradiated catla compared to the control larvae. Comet assay analysis indicated that UV-B irradiation enhanced DNA fragmentation. Tail extent moment and the olive tail moment were significantly (P <0.05) higher in 2016mJ/cm(2) UV-B exposed catla compared to others. The tail length was significantly (P <0.05) higher in 1512 and 2016mJ/cm(2) UV-B exposed larvae compared to the other doses. The present study suggests that the catla is a useful species for the biomonitoring of stress in the aquatic environment.

Biofunctionalized Nanostructured Zirconia for Biomedical Application: A Smart Approach for Oral Cancer Detection.

Results of the studies are reported relating to application of the silanized nanostructured zirconia, electrophoretically deposited onto indium tin oxide (ITO) coated glass for covalent immobilization of the monoclonal antibodies (anti-CYFRA-21-1). This biosensing platform has been utilized for a simple, efficient, noninvasive, and label-free detection of oral cancer via cyclic voltammetry technique. The results of electrochemical response studies conducted on bovine serum albumin (BSA)/anti-CYFRA-21-1/3-aminopropyl triethoxy silane (APTES)/ZrO2/ITO immunoelectrode reveal that this immunoelectrode can be used to measure CYFRA-21-1 (oral cancer biomarker) concentration in saliva samples, with a high sensitivity of 2.2 mA mL ng-1, a linear detection range of 2-16 ng mL-1, and stability of six weeks. The results of these studies have been validated via enzyme-linked immunosorbent assay.

Orientation behaviour of Pagrus major larvae exposed to UV-B radiation in laboratory conditions.

PURPOSE: The increasing intensity of ultraviolet-B (UV-B) radiation is a potential threat to the aquatic environment. The recognition capacity of the aquatic animals may help them to avoid this harmful radiation. The response of individual species, especially during early development may help to understand the vulnerability of that species and its potentiality in natural fishery. MATERIALS AND METHODS: The orientation behaviour of red sea bream Pagrus major larvae exposed to UV-B radiation (280-315 nm) was studied within the laboratory (1.41 W/m(2)) under following experimental conditions: (i) two fluorescent lamps fixed above the tank, (ii) one fluorescent lamp on the left side, one fluorescent lamp and one UV-B lamp on the right side, and (iii) one UV-B lamp and one fluorescent lamp on the left side, one fluorescent lamp on the right side of the tank. RESULTS: In the first treatment, 7- and 20-day-old larvae were significantly (p < 0.0095) higher in number at the right side than left and middle regions of the tank. Some 33-60% of larvae were found in the middle region of the tank at the age of 30-32 days. In the second treatment, significantly (p 5 0.0034) lower numbers of larvae (10-13.3%) were found in the middle region of the tank compared to the other sides between days 17 and 20, whereas 40- 86.67% larvae were found in the middle region between days 25 and 36. In the third treatment, significantly (p < 0.015) higher numbers of larvae were found in the right side at the age of days 17-25 and in the middle region between days 32 and 36. CONCLUSIONS: This study showed that UV-B sensitivity of P. major developed during ontogenic development. Care should be taken at early stages.