Quantitative real-time RT-PCR (qRT-PCR) is the most sensitive and advanced method to quantify the expression of target genes of animals including fish. However, the broad variation in the expression ...patterns of housekeeping genes (HKGs) among tissues and different developmental stages makes it necessary to conduct studies for the selection of the suitable internal control. There is no report available on the reference genes for normalization of gene expression studies in
Pterophyllum scalare
. In the present study, four reference genes, viz. alpha-actin (α-actin), beta-actin (β-actin), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and elongation factor-alpha 1 (EF1α), were first characterized and then screened for their efficacy as a suitable HKG at different developmental stages and tissue types of
P. scalare
. The different statistical algorithms such as Delta-cT, NormFinder, and geNorm portray β-actin to be the most suitable gene among the four genes, whereas BestKeeper revealed EF1α as the most stable reference gene during different developmental stages and tissue types. However, comprehensive gene stability method demonstrated β-actin to be the most stable gene for conducting any gene expression studies. In conclusion, β-actin is recommended as the most suitable reference gene among the four selected genes for qPCR data normalization during different developmental stages and tissue types of
P. scalare
.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Arcobacter butzleri is an emerging pathogen isolated from animals, food and the environment. In this study, 147 A. butzleri isolated from seafood and the coastal environment were tested for the ...presence of ten putative virulence genes (cadF, cj1349, ciaB, mviN, pldA, tlyA, hecA, hecB, irgA, iroE) and antimicrobial susceptibilities. Majority of the isolates harbored mviN (100%), cj1349 (97.2%), ciaB (95.9%), tlyA (91.8%), pldA (91.1%) and cadF (89.7%). Lower detection rates were observed for hecA (10.8%), hecB (19%), iroE (12.9%) and irgA (17.6%). Three A. butzleri isolates harbored all ten virulence genes. The occurrence of cj1349, ciaB, pldA, tlyA and hecA genes was significantly different (P≤0.05) among the isolates from different sources. All (100%) A. butzleri isolates were resistant to vancomycin, cephalothin, cefoxitin and sulphamethizole and susceptible to polymyxin-B, kanamycin, streptomycin, gentamicin, tetracycline and imipenem. Resistance to clinically important antibiotics such as cefotaxime (99.3%), ceftazidime (87.7%), nalidixic acid (70.7%), ampicillin (72.1%), ertapenem and amoxicillin-clavulanic acid (41.9%) was observed in A. butzleri from the environment. The isolates were highly susceptible to norfloxacin (97.9%) and colistin (97.2%), followed by ciprofloxacin (88.4%), meropenem (74.8%), chloramphenicol (72.7%) and erythromycin (69.3%). A. butzleri from different sources were not significantly different with respect to their antimicrobial susceptibility patterns. Multidrug resistance was observed in 66 (81.4%) isolates from fish, 29 (72.5%) isolates from shellfish and 17 (65.3%) isolates from coastal water. A. butzleri harboring virulence genes and resistance to multiple antibiotics found in seafood could be a potential health risk to seafood handlers and consumers. Continuous monitoring of seafood for potentially pathogenic A. butzleri is important to understand the evolution of antibiotic resistance in this emerging food pathogen and to determine the antimicrobial therapy regimen in the event of food-borne A. butzleri infections.
•Six putative virulence genes were found in majority (>85%) of the isolates.•Three A. butzleri isolates harboured all ten virulence genes.•Multidrug resistance was observed more in fish-derived A. butzleri isolates, followed by shellfish and coastal water isolates.•Aminoglycosides, fluoroquinolones and carbapenems are among effective chemotherapeutic agents against A. butzleri.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Aeromonas
spp are the most common devastating fish bacterial pathogens associated with a wide range of cultured freshwater fish resulting in mass mortality. The present study plots the
Aeromonas
...research output in fish during 1998–2020 by means of the Web of Science (WoS) database. A total of 1944 publications were used for this investigation to evaluate the scientific productivity in this selected subject area. Global publication share, rank, and its development in terms of research and bibliometric indices such as overall citations, h-index, and average citation per paper were also analysed. China ranked first in terms of total publications among the most productive countries and accounted for 26.18% of the total publications. The network visualisation map revealed that the lead collaborating country was China; however, the collaboration between countries was found to be very less. Lokta’s law was noticed not to be valid for
Aeromonas
research. The study showed that the funding granted to the research investigations and their research productivity in terms of total publications were correlated positively. The results of the current study displayed the trend of “
Aeromonas
infection in fish” related research investigations published during 1998–2020. This study also highlighted the focused research areas on this topic on which the future areas of research can be determined by fellow researchers in this specific field. This study also suggests enhancing the research efforts on this bacterial pathogen which has the potential to implicate huge economic loss to the fish farming population in the world.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Evolution of invertebrate immunity.•Genetic traits and immune components of non-bilaterians and bilaterians immune system.•Innate immune mechanisms in marine invertebrates.
The present article ...provides insights into the immunity of ocean invertebrates. Research in this field has revealed hallmark components and strategies of the animal immune system, which have both theoretical and practical utility. From phylum Porifera to arthropods, animal immunity has evolved over various timescales. Within these timescales, dynamic environmental factors and microbial influences have shaped invertebrate immunity in an adaptive manner, resulting in the acquisition of complex genetic traits. These genetic traits play a crucial role in coding for multiple components, including antigens binding to cellular and cytoplasmic receptors, antimicrobial peptides, proteases, and proteins in pioneer animals. Marine invertebrates, such as sponges, cnidarians, mollusks, echinoderms, and crustaceans, exhibit diverse innate immune mechanisms influenced by their environment and microbial interactions. Despite lacking adaptive immune responses, marine invertebrates rely primarily on innate immunity. Their immune system encompasses physical and chemical barriers that prevent pathogen entry, as well as specialized cells and humoral factors that combat infections and minimize potential damage. In summary, this review explores the immunity of ocean invertebrates, highlighting key discoveries related to both cellular and humoral defenses across various marine species.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Tilapia lake virus (TiLV) is a serious pathogen of farmed Nile tilapia (
Oreochromis niloticus
) responsible for significant mortalities. In this study, we investigated a disease outbreak in ...cage-farmed Nile tilapia in India. The infected fish exhibited clinical signs such as severe scale loss, haemorrhage, exophthalmia, and fin and tail rot. The samples were screened for Tilapia lake virus (TiLV) by reverse-transcriptase PCR and also subjected to detailed bacteriological investigation to understand the association between TiLV and co-infecting bacterial pathogens. Bacteria were isolated from TiLV-infected and apparently healthy fish, and identified by conventional microbiological methods, followed by 16SrRNA gene sequencing. TiLV was detected by PCR in all the samples exhibiting clinical signs, while apparently healthy fish were negative for the virus. A total of 34 bacterial isolates belonging to the genera
Aeromonas
,
Staphylococcus
,
Enterococcus
,
Plesiomonas
,
Enterobacter
,
Bacillus
,
Lysinibacillus
,
Solibacillus
and
Exiguobacterium
were isolated from the virus-infected tilapia. However,
Aeromonas veronii
was found to be the most dominant bacterium isolated from the surface lesions and the internal organs of all infected fish. Antibiotic susceptibility testing revealed that
A. veronii
, by far, was susceptible to cephalosporins (ceftriaxone, cefotaxime, cefpodoxime), chloramphenicol, aminoglycosides (amikacin, gentamicin), ciprofloxacin and chloramphenicol. Experimental infection using intraperitoneally injected
A. veronii
reproduced the clinical signs of naturally infected Nile tilapia, and a lethal dose 50 (LD
50
) mortality was observed by day 7 post-challenge. Furthermore,
A. veronii
could be re-isolated from the experimentally infected fish. Based on this evidence, we propose that virulent
A. veronii
as a co-infecting bacterium can have an important role in the severity and outcome of the disease in Nile tilapia infected by TiLV.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A novel myxozoan parasite is identified and described from mudskipper,
Boleophthalmus dussumieri
, collected from a brackishwater ecosystem in Maharashtra, India.
Ellipsomyxa boleophthalmi
sp. nov. ...was found in the gallbladder of 58 of 60 fish examined (96.7%). The parasite formed disporous plasmodia that varied in size and shape, and the thin-walled, ellipsoidal and elongated myxospores measured 9.0–10.7 × 6.0–7.8 μm. The two, spherical polar capsules measured 2.7 μm in diameter and enclosed 3–4 coils of polar tubules. Histological observations of infected gallbladder revealed the attachment of disporous plasmodial stages of the parasite to the gallbladder wall with fine pseudopodia. Under the scanning electron microscope (SEM), the myxospores showed a distinct central sutural line and two distinct depressions on the opposite sides at the openings of polar capsules. SEM also revealed the engulfment of microvilli of gallbladder wall by pseudopodia of the plasmodial stages. Analysis of the partial fragment of the SSU rDNA region (1386 bp) showed less than 98% sequence similarity with the other reported
Ellipsomyxa
spp. In the phylogenetic tree, the present species formed as a distinct subclade within the major clade of
Ellipsomyxa
spp. The unique morphological and morphometric features of the myxospore, together with the molecular analysis, allowed us to conclude that the present myxozoan is a new species and is named
Ellipsomyxa boleophthalmi
sp. nov., after the generic name of the host. This is the first report on the occurrence of the genus
Ellipsomyxa
in
B
.
dussumieri.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Purpose
Similar to fresh- and brackish water aquaculture ponds, commercial shrimp farming in degraded saline areas holds the potential to bury carbon (C) in the sediments. However, studies on the ...mechanisms of sediment C dynamics and C-flux in response to inland saline aquaculture management practices are still scarce. Therefore, the objectives of the present study are to quantify the C burial rate in inland saline aquaculture ponds and assess the impact of inland saline aquaculture on sensitive C fractions in the bottom sediment of the ponds.
Materials and methods
The sediment samples (
n
= 12 from each pond) were collected from six shrimp farming ponds (1000 m
2
area of each pond) of different ages. The sediment depth, sediment accumulation rate and the levels of total carbon (TC), total organic carbon (TOC) and sediment oxidizable organic carbon (SOC) and its different fractions were determined using standard procedures. The data were analysed by one-way analysis of variance (ANOVA), followed by the Duncan's multiple range test for comparing the means, and the Pearson correlation test was used to assess the relationship between the different pond sediment parameters and SOC content.
Results and discussion
The results revealed that the annual C accumulation rates varied from 902 to 1346 kg C ha
−1
year
−1
in 7-year-old earthen ponds (EPs) and bottom cemented ponds (BCPs), respectively. The sediment C fractions, including TC, TOC, SOC and its fractions (very labile, VLc; labile, Lc; less labile, LLc), and non-labile carbon (NLc)) were progressively increased over the pond age. The inland saline aquaculture practices over the years increased both active (AC) and passive carbon (PC) pools in the pond sediments, helped in the restoration and improvement of sediment quality and enhanced C sequestration potential of the sediments. Furthermore, a significant increase in the level of particulate organic carbon (POC) in BCPs justified that the non-ploughing practices at BCPs facilitated the formation of macro- and micro-aggregates, thereby increasing the C retention and stability of the pond sediments.
Conclusion
This study suggested that the shrimp farming ponds in semi-arid saline soils represented considerable C burial hotspots, enhanced the stable passive C pools and improved the sediment quality.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
TLR5 is one of the important PRR (pathogen recognition receptors) and plays a fundamental role in pathogen recognition and activation of innate immune responses. It recognizes bacterial flagellin and ...stimulates the production of proinflammatory cytokines, through signalling via the adaptor protein MyD88. In this study, we characterized partial TLR5 (soluble form) gene from Pangasianodon hypophthalmus and analysed its expression profile upon challenge by Edwardsiella tarda. Bioinformatic analysis of gene sequence revealed a putative protein of 266 amino acids with four Leucine rich repeats. Quantitative expression analysis of TLR 5S showed its wide distribution in various organs and tissues. However, significant expression of TLR5S was observed in liver and spleen at 12 h (∼207.8 fold, p < 0.05). Significant upregulation was observed in kidney at 72 h.p.i. (50 folds, p < 0.05) indicating that the kidney provides longer protection almost till the activation of the adaptive immune system. This study enriches the knowledge of TLR5S in boosting the innate immunity against bacterial invasion in fish.
•We identified and partially characterized the Toll like receptor 5 in P. hypophthalmus.•The catfish TLR 5 gene is variously expressed in different immune organs at different time intervals against E. tarda infection.•We studied histopathological changes in various tissues of catfish against E. tarda infection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Rohu (Labeo rohita), an Indian Major Carp (IMC) is an economically important aquaculture species in India. Inspite of the technological advances, infectious diseases caused by viruses, bacteria and ...parasites have been a major limiting factor in the development and profitability of fish farms. At present, information regarding the immune status of the Indian major carps is limited. This lack of knowledge is a major impediment for establishment of effective preventive measures against broad spectrum of infectious agents. The present study was undertaken to examine the modulation of few immune-regulatory genes: IgHC, NOD 1, TLR 22, iNOS and IL-1β during experimental infection of E. tarda in L. rohita to understand their role in pathogenesis. Rohu fingerlings were intra-peritoneally injected with Edwardsiella tarda (LD50 dose of 8.7 × 104 CFU/fish) and sampled for three immunologically important organs (kidney, liver and spleen) at different time intervals (zero hour or pre-challenge and 6 h, 12 h, 24 h, 48 h and 96 h post challenge). For absolute quantification of genes by real time RT-PCR, all the genes transcript were amplified from Poly I:C induced rohu lymphocytes and cloned in pTZ57R/T plasmid. Standard curves for each gene was generated from serially diluted plasmid bearing respective genes. Evaluation of copy number of different genes present in the tissue showed that the expression of IgHC, iNOS and IL-1β was highest in kidney followed by spleen and least in liver. While for NOD 1 and TLR 22 gene, liver showed higher expression than kidney and spleen. Further, the expression of IgHC, INOS, TLR 22, NOD 1 and IL-1β genes significantly differed (P < 0.05) in the E. tarda challenged fish when compared with pre-challenged control fish. Among the five genes we studied, the basal expression of TLR 22 gene was highest. The result also depicts that iNOS and NOD 1 are immediate responsive genes as their expression reached maximum level at 6–24 h post infection (hpi) after which the expression declined. In contrast, TLR 22 and IgHC gene transcript showed enhanced expression during the late phase of with maximum expression observed after 48 hpi and 96 hpi respectively. IL-1β, being the exception, showed high expression both at 24 hpi and 96 hpi. From this study, we conclude that these five immune genes have a definite role to play in the defense mechanism of host (L. rohita) against E. tarda.
•Pathogenesis related to Edwardsiella tarda on Labeo rohita was studied.•E. tarda exposure modulates TLR22, NOD1, IgHC, iNOS, IL-1β expression in L. rohita.•Involvement of various immune pathways in disease processes was determined.•Expression patterns demonstrated orchestration of various organs in host defences.•Absolute quantization method used can be a referendum for various gene transcripts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
