Depth distribution and ecological preferences of periphytic algae in Kenyir Lake,the largest tropical reservoir of Malaysia

We studied the depth distribution of periphyton,growing on inundated dead trees in Kenyir Lake,Malaysia in June 1995.The algal floral composition and structure manifested changes down the depth gradient in terms of species richness,abundance,diversity and cell density.In regression analysis,all these algal attributes were negatively correlated with the depth gradients at P<0.05.In terms of species richness,the bacillariophytes showed dominance over the cyanophytes and chlorophytes;whereas with respect to standing crop,the cyanophytes showed dominance over the bacillariophytes and chlorophytes.The chlorophyll a was higher at the mid and bottom-depths than the surface-depth in both the downstream and upstream sites,which showed that vertical productivity or biomass accumulation was greater in low light irradiance.The product-moment correlation analysis showed that conductivity,turbidity,dissolved oxygen,reactive phosphate and ammonium-nitrogen were highly correlated with the algal assemblage data.However,photosynthetic active radiation(PAR) showed poor correlation with the community data.These observations have cast some light on the autoecological characteristics,habitat preferences and environmental responses of tropical periphytic communities.

A Review of Various Sources of Chitin and Chitosan in Nature

Chitin was first discovered by its name from the Greek word“chiton”,which means“mail coat”.It is indeed a polysaccharide made up of naturally occurring acetyl-D-glucosamine monomers.Hatchett was the first researcher who extracted chitin from the shells of mollusks(crabs and lobsters),prawns,and crayfish in 1799.Later in 1811,Henri Braconnot discovered chitin in the cell walls of mushrooms and called it“fungine”.Chitin and chitosan are abundant in the biosphere as essential components of many organisms’exoskeletons and as by-products of the global seafood industry.The biopolymer must be deacetylated before chitosan can be produced.It can also be extracted using microbes in a biological extraction procedure.The development of products that take advantage of the bioactivities of the existing primary commercial source of chitin(crustacean)has lagged expectations.Also,the disadvantages of the present commercial source such as seasonality and competition for other uses among others has been one of the driving forces towards seeking alternative sources of chitin and chitosan in nature.This review highlights some of the efforts made by environmental scholars to locate possible commercial sources of chitin and chitosan in nature over time.

Zonal distribution and population biology of Ilyoplax frater (Brachyura:Ocypodoidea:Dotillidae) in a coastal mudflat of Pakistan

Zonal distribution and population biology of Ilyoplax frater were studied in a mangrove mudflat area of Pakistan.The crabs were collected from Korangi creek through transect and quadrat method from low tide level to high tide level. Twotransects were delimited in a mangrove area of Korangi creek (24°79'N/ 67°20'E). On each transect, three 0.25 m quadrats weresampled at three tidal levels on a monthly basis during low tide periods from March 2001 to February 2002. A total of 1124 crabswere obtained, of which 482 were males and 642 were females. Density of crabs varied between 0 and 90 /m'. The density andsize distribution varied and showed significant differences from low to high tide level, and were positively correlated with thepercent moisture, percent organic matter and sediment grain size. The carapace width (CW) ranged from 2.5 to 11.5 mm for maleand 2.5 to 11.0 mm for female and was not significantly different. The overall sex ratio did not differ significantly from the expected1:1 throughout the year in small crabs but was significantly different in adult crabs (x^2= 49.73) with more male crabs. Sizefrequency distribution showed recruitment of juvenile crabs (< 4 mm) nearly throughout the year except during June and July.Presence of ovigerous females in all months with seasonal peaks in September, October, December and May indicates seasonalcontinuous breeding. Weight of egg mass increases with weight of ovigerous females and show positive linear relationship. Theestimated mean diameter of egg was 2.83±0.25μm, and the average number of eggs was

New Discovery of Hipparion theobaldi Skull from the Late Miocene of Padhri,District Jhelum,Punjab,Pakistan and Associated Mammalian Fossil Assemblage

A fossil-bearing locality near Padhri village,Dhok Pathan,55 km away from the tehsil Dina,Jhelum District,in the Potwar Plateau,Middle Siwaliks,Punjab,northern Pakistan,is significantly rich in mammalian fossils.This site has provided an abundant mammalian fossil fauna of Late Miocene age from the Dhok Pathan Formation(Fm.).The recovered material belongs to four families:Equidae(horses),Rhinocerotidae(rhinos),Bovidae(cows),and Suidae(pigs).We discovered a new skull of hipparionine Hipparion theobaldi from this locality along with 22 specimens from the associated assemblage of fossil mammals.The recovered material includes seven other species:the aceratheriine Chilotherium intermedium,boselaphines Tragoportax punjabicus,Selenoportax vexillarius,Pachyportax latidens,the antelope Gazella lydekkeri and suinine Propotamochoerus hysudricus.The specimens are isolated teeth,fragments of maxilla,mandibles and horn cores.The Dhok Pathan Fm.is generally composed of claystone,siltstone and sandstone beds and,based on the mammalian fauna,the Padhri fossil locality is dated as Late Miocene.Thi99 s formation was deposited in a subtropical paleoenvironment and the predominance of fossil bovids indicates extremely moist conditions with small but frequent standing water bodies.

Population Biology of the Metazoan Parasites Infecting Fishes from Lakes Uba and Ruwe, Lower Rufiji Floodplain, Tanzania

Out of the 48 fishes examined, 40 (83.3%) were infected by 759 parasites, which comprise of trematodes, monogeneans, crustaceans and acanthocephalans. Acanthocephalans and strigeid trematodes were the majority, 23 (47.9%) of all the parasites, while crustaceans, Ergasilus was the minority (20.8%). Fish with length size greater than 160 mm were infected (prevalence 100%). Strigeids showed the highest prevalence (83.3%) and mean intensity (24.7) in fish of total length 160 - 189 mm while those greater than 219 mm had the least prevalence (20%) and mean intensity (2). Acanthocephalan showed the highest prevalence (87.5%) and mean intensity (15.7) in fish of total length 190 - 219 mm and least prevalence (30.4%) and mean intensity (5.6) in those with 130 - 159 mm in total length. Generally male fish had higher prevalence (88.5%) and mean intensity (21.6) than female fish. However, statistically these were not significant (P > 0.05). A total of 9 parasite taxa were recovered;5 from Oreochromis urolepis, 4 from Citharinus congicus, 2 from Clarias gariepinus and Synodontis maculipinna. Three groups of parasites were common in Oreochromis urolepis, these include Dactylogyrus, Acanthocephala, and strigid. Ergersilus lamelifer was common in Citharinus congicus and Clarias gariepinus. Nematodes, Procamalanus laevionchus and Oxyuridae were common in Synodontis maculipinna and Citharinus congicus respectively.

Growth Performance and Serum Lipids Profile of Clarias gariepinus Catfish Following Experimental Dietary Exposure to Fumonisin B1

Fumonisin B1 (FB1) is produced by fungus of the genus Fusarium (Fusarium verticiloides and F. proliferatum), and occurs predominantly in maize. The consumption of feed contaminated with FB1 has been reported to cause deleterious effects in some fish species. This study was designed to determine the effects of dietary FB1 on growth and lipids profile of Clarias gariepinus. 450 juvenile catfish were stocked into 5 groups of tanks consisting of 3 tanks per group and fed one of five diets amended with FB1 (0.0 mg;10.0 mg;20.0 mg;40.0 mg and 80.0 mg FB1/kg) for 56 days. At time point’s day 7, 14, 28 and 56, five fish were sampled from each tank weighted, length measured and bled for of lipids profile determinations. Results show that there was a significant reduction (P < 0.05), in the mean body length of the fish fed diets amended with various amounts of FB1 compared with those fed control diet;also, there was a significant reduction (P < 0.05) in the weight gain of fishes fed diets amended with FB1 compared with the control. The specific growth rate and the feed conversion ratio at 56 days shows fish fed 0.0 mg FB1/kg had the highest specific growth rate (0.39 ± 0.14%/day) and the lowest feed conversion ratio (0.59 ± 0.01) whereas, fish fed 80.0 mg FB1/kg had the least specific growth rate (0.07% ± 0.01%/day) and the highest feed conversion ratio (1.95 ± 0.11). Dietary FB1 caused significant increases (P < 0.05) in serum cholesterol, HDL-C;LDL-C;triglycerides and the sphinganine-sphingosine ratio. Dietary FB1 at an inclusion rate ≥ 20 mg FB1/kg of diet produced significant reduction in weight gain and hyperlipidemia marked by hypercholesterolemia, increased blood high-density lipid cholesterol, increased blood low-density lipid cholesterol, elevated blood triglycerides and elevated sphinganine-sphingosine ratio.

Fillet Quality and Gut Content Analysis of Parachanna obscura and Clarias agboyiensis

Nigeria waters are rich with a variety of fish species but only very few are cultured and available for consumption.This study was conducted to know the fillet quality,gut content and condition of Parachanna obscura and Clarias agboyiensis in Nigeria using Igbokoda river as a reference because it is a the major fishing site in the nation.Studies were conducted on the viscera somatic index based on the organ weight and the body weight of the fish and the food item consumed by Parachanna obscura and Clarias agboyiensis between May to October,2019 to infer on the fillet quality and gut content of P.obscura and C.agboyiensis in the water body respectively.A summary of food items that constituted the diet of Clarias agboyiensis are Baccillariophyta,fish,fat droplets,dinoflagellate,insect and Chlorophyta which constituted the most important food items both occurring in all stomachs containing food.The fishes has more muscle than the viscera organs which indicate that the weight of the fish before dressing out is higher than the weight of the fish after dressing out.This is suggestive of a good quality of food fish.There was a significant correlation between body weight and total length of specimens found in this study.Increases in total length resulted in corresponding increases in body weight.The result for the condition factor showed was below the expected or standard value(K=1)which shows this species was not in favorable environmental condition.It is therefore necessary to allow phytoplanktons grow well in water body to increase availability of food items to Parachanna obscura and Clarias agboyiensis.P.obscura and C.agboyiensis are also good food fishes of a high fillet quality.They are omnivorous feeders therefore having potentials for aquaculture.

Antibiotic Resistance and Heavy Metals Tolerance in Gram-Negative Bacteria from Diseased American Bullfrog (Rana catesbeiana) Cultured in Malaysia

A total of 140 bacterial isolates have been successfully isolated from various organs of diseased American bullfrog （Rana catesbeiana） cultured in Malaysia. The most frequently isolated bacteria was Edwardsiella spp. （46 isolates） followed by Aeromonas spp. （33 isolates）, Flavobacterium spp. （31 isolates）, and Vibrio spp. （30 isolates）. Majority of the bacterial isolates were found sensitive to furazolidone （85.0%）, chloramphenicol （85.0%）, oxolinic acid （90.0%）, florfenicol （95.0%）, and flumequine （97.5%）. On the other hand, most of the bacterial isolates were resistant to oleandomycin （77.5%） and lincomycin （87.5%）. Nitrofurantoin and flumequine can be inhibited the growth of all of Vibrio spp. whereas all isolates of Edwardsiella spp. were found sensitive to florfenicol and flumequine. Multiple antibiotic resistance （MAR） index were in range of 0.30-0.40, indicating that bacterial isolates from cultured bullfrogs may have received high risk exposure to the tested antibiotics. In addition, 90-100% of the isolates were resistant to copper, cadmium, and chromium. These results provided insight information on tolerance level of bacterial isolates from cultured bullfrogs to 21 antibiotics as well as heavy metals.

Response of African Catfish, <i>Clarias gariepinus</i>(Burchell 1822), Fingerlings Fed Diets Containing Differently Timed Wet-Heat-Treated Sesame (<i>Sesamum indicum</i>) Seedmeal

The response of catfish fed differently timed wet-heat-treated sesame seedmeal was evaluated in the diet of Clarias gariepinus using growth performance, nutrient utilisation and apparent digesti-bility coefficient as indices. Three batches of sesame seed, which were cooked for 10, 20 and 30 minutes, dried, milled, and mechanically defatted using locally made screw press. Each of these differently processed seedmeals was included in the diet of African catfish at varying replacement levels, 15, 30 and 45% with soybean meal. There was good growth performance and nutrient uti-lization by Clarias gariepinus fed with differently timed wet-heat-treated sesame seed that was not significantly different (p > 0.05) from fish fed control diet. More so, the apparent digestibility coef-ficient for organic matter, protein, energy, lipid, fibre, carbohydrate in Clarias gariepinus fed with differently timed wet-heat-treated sesame seedmeal based diets in this study were comparable with the results obtained for fish fed control diets.

Trophic attributes of the mudskipper, Periophthalmus barbarus (Gobiidae: Oxudercinae) in the mangrove swamps of Imo River Estuary, Nigeria

Aspects of the trophic attributes of the mudskipper, Periophthalmus barbarus occurring in the mangrove swamps of Imo River Estuary, Nigeria, were investigated during a 12 month period (April, 1992\_March, 1993). Feeding intensity increased with size, it was higher in the dry season(November\_April) than in the wet season(May\_October), monthly changes in the indices of feeding intensity were significantly correlated. Major food objects comprised detritus and benthic algae; crustaceans, insects, macrophyte matter and sand grains were minor food objects while fish, molluscs, Chilopoda, nematodes and fungi were unconsciously devoured objects. Diet varied seasonally; algae and sesarmid crabs were generally more in the dry season than during the rains whereas FPOM and fish increased in the wet over dry season. The mudskipper display a high degree of euryphagy and can be considered as a generalist and an omnivore. The lower trophic status of P. barbarus qualifies it as a good aquaculture candidate. Food richness was higher in big sized class(BSC) than small sized class(SSC). Size based and seasonal variations were not apparent in food richness. Diet breadth was higher in the BSC than the SSC, there was dry season increase in diet breadth.

Some Aspects of Ecology of Chrysichthys nigrodigitatus (Lacepede) in River Niger, Nigeria

A study on the food and feeding habit of Chrysichthys nigrodigitatus （Lacepede） was conducted in River Niger within the region of Oshimili local government area of Delta State Nigeria. A total of 90 specimens were collected with the help of fishermen using gill net, cast net and traps. The fish samples were immediately taken to the laboratory for analysis. Morphometric characteristics such as weight, length, condition factor, egg weight, Gonado Somatic Index （GSI） and sex ratio were determined. The stomach content was analyzed using numerical method to determine the food content. The total length of the fish sampled ranged from 14.40-44.60 cm, while the standard length varied from 11.00 cm to 47.00 cm and the fish body weight ranged between 19.00 g to 503.20 g. Sex ratio 1 female to 1 male was observed. The mean condition factor for both male and female obtained was 1.67. Of all the 90 fishes sampled, none had empty gut representing 100%. The major food items were phytoplankton, plant part and Detritus. Out of 41 females sampled, only 17 had eggs and the eggs were matured at stage IV.

Experimental Culture of the Giant Freshwater Prawn, Macrobrachium vollenhovenii (Herklots, 1857) around the FUTO Axis of Otamiri River, Imo State, Nigeria

Culture trial of 7,488 juveniles of the giant freshwater prawn, Macrobrachium vollenhovenii (Herklots, 1857) was carried out for 180 d in concrete tanks to determine their adaptability, survival, feed utilization and growth performance under culture condition. Twelve experimental concrete tanks each measuring 10 m × 5 m × 1.0 m were used for the experiment from March to August 2016. The prawns were stocked two weeks after treatment of tanks with agricultural lime at the rate of 2,279 kg/ha and poultry manure at the rate of 114 kg/ha. Four experimental diets tested were designated as T1: powdered broiler starter, T2: commercial brine shrimp, T3: combination of broiler starter and brine shrimp and T4: Mississippi Agricultural and Forestry Experimental Station (MAFES) diet formula. Diets were randomly assigned to the four treatment tanks and replicated three times in a 4 × 3 = 12 experimental units as a completely randomized design experiment (CRD). Each tank was stocked with 624 juvenile prawns with mean total length of 1.5 cm and body weight of 10.0 g. Prawns were fed at 5% body weight and twice at 0600 h and 1800 h. Sampling for growth was carried out bi-weekly while water quality was tested weekly. Results were statistically evaluated with one way analysis of variance (ANOVA). Water quality of the four tanks was not significantly different (p > 0.05) from one another throughout the culture period and conformed to recommended tolerable limits in prawn culture ponds. Growth performance was best in diet T4 (the MAFES formula), with a survival rate of 75%, mean weight gain (MWG) of 65 g, relative growth rate (RGR) of 650%, specific growth rate (SGR) of 1.12%, average daily growth (ADG) of 0.3 g/day and food conversion ratio (FCR) of 1.44. The above values differed quite significantly (p < 0.05) from growth responses of other diets. The computed gross ratio (GR) of 0.62 suggests that prawn culture is a highly lucrative business.

Physical Characteristics of Functional Indigenous Farm-made Feeds Using Crude or Gelatinized Tapioca Starch as Sources of Energy

The experiment compared the physical characteristics of aqua feed with crude or gelatinized tapioca starch as sources of energy.The bulk density(BD),water absorption index(WAI),water solubility index(WSI),pellet durability index(PDI)and water stability(WS)were measured in both experimental diets.The results showed significant variations(p<0.05)in BD and WAI in diet with crude tapioca starch while non-significant variations(p>0.05)were recorded for WSI and WS in both diets.The higher BD of a diet,the better its ability in resisting external forces that can cause disintegration.A high BD also reduces ability to the feed material shrinking,thereby preventing loss to feed dust and fines.The results of WSI,WS and PDI of diets denotes that both pellets were water stable and could spend about same time in water but diet with gelatinized starch had a better water absorption index and pellet durability index.Furthermore,proximate composition of diets showed that diets with gelatinized starch had low moisture(9.04%),low fibre(5.24%),and higher ash(13.61%)and lipid(9.64%)contents.It can be concluded from this experiment that diets with gelatinized starch stands the chance of being a better functional feed for small-scale fish farmers in Sub-Saharan Africa.

Effects of Dietary Replacement of Maize with Sweet Potato Peel in the Diet of African Catfish Clarias gariepinus(Burchell,1822)

This study was carried out to evaluate the effects of dietary replacement of maize with sweet potato peel in the diet of Clarias gariepinus juveniles.The levels of the SPP inclusion in the experimental diets were 0%,25%,50%,75%and 100%.All the diets were iso-nitrogenous.One hundred and fifty(150)C.gariepinus juveniles(33 g~35 g)were randomly distributed to five treatments with three replicates each and 5%of their body weight for 12 weeks.Fish carcass proximate compositions analyzed before and after feeding with the experimental diets shows that CP and EE differed significantly(p<0.05)among the experimental fish and the control,except the percentage CP of the fish fed SPP0%and SPP50%in which there was no significant difference(p>0.05).Highest MWG of 207.70±25.95 g was obtained in the fish fed SPP100%followed by 191.30±16.15 g obtained in the fish fed SPP75%.The least MWG of 149.83±16.01 g was recorded in fish fed SPP25%.The highest FCR of 3.61±0.45 g was recorded in the fish fed SPP100%.A steady decrease in FCR was observed with decreasing inclusion levels of SPP meal.However,higher FW,FL,SGR and PER were observed in the experimental fish as from 50%inclusion levels of the SPP.The cost of feed per kg was reduced and the NP and WG increased with increasing levels of SPP and the profitability was enhanced at 100%SPP inclusion level.The results revealed that C.gariepinus juvenile could tolerate up to 50%,75%and 100%inclusion levels of SPP.The best growth performance was recorded in the fish fed SPP100%,therefore,sweet potato peel can replace maize in the diet of C.gariepinus without any inauspicious effect on the growth performance and nutrient utilization.

Molecular mechanism of different viruses associated with autoimmunity

Different kinds of human chronic diseases may develop the mechanism of autoimmune diseases.As a group of disorders,in the Western world autoimmunity possess as the third most prevalent morbidity and mortality.However,the mechanism of most autoimmune diseases is still under investigation.Viral infection is the principal factor involved in the induction of autoimmune diseases other than genetic factors and cytokine activity.Different mechanisms have been proposed by which viral infection might interrupt tolerance to self and induce autoimmune cascade which eventually leads to the destruction of a specific type of cell or a whole-body organ.The autoimmune attack can be understood through the different immune systems and other possible mechanisms such as molecular mimicry,bystander activation and epitope spreading.In addition to genetic and viral factors,other environmental factors are also involved including bacterial,parasitic and fungal infections.However,different animal models have been studied which provide strong evidence that viruses induced AIDs as well as accelerated and increased lesions in conditions where self-tolerance is interrupted.In the current review,we discussed the virus-induced autoimmunity and the molecular mechanism which is associated with this phenomenon.Here we also discussed the different viruses such as rubella virus,enteroviruses,measles virus,human T-lymphotropic virus type1,human cytomegalovirus,human herpes virus-6,Epstein-Barr virus,rotavirus and some other viruses which modulate the development of AIDs.

A genetic linkage map of the threatened catfish Lophiosilurus alexandri:Inferences on effective population size

We report the first genetic linkage map of the catfish Lophiosilurus alexandri,a South American threatened and promising aquaculture catfish species.Using the progeny of three full-sib families,with 141,74,and 49 offspring,respectively,we could genotype 2351 SNP markers using the ddRAD technology,shared by the male and the female maps constructed.The averaged,female and male maps spanned a total length of 2201.3 cM,2481.9 cM,and 1872.8 cM,respectively,and comprehended the expected 27 linkage groups according to the karyotype information of the species(2n=54).The recombination rate was nearly twice higher in the female than in the male map.The average map was used to estimate the historical effective population size(Ne)of the species from linkage disequilibrium between pairs of SNPs using parental individuals and revealed a remarkable drop in Ne about 20-25 generations in the past.The construction of the biggest artificial reservoir in Latin America and associated nutrient retention is pointed as a possible reason for such a reduction and suggests a reevaluation of the conservation status of the species.The current map lays the groundwork for understanding the genetic basis of economically important traits in breeding programs and will be useful for the genome assembly of this important commercial species.

Molecular evolution,virology and spatial distribution of HCV genotypes in Pakistan:A meta-analysis

Background:Hepatitis C,caused by the Hepatitis C Virus(HCV),is the second most common form of viral hepatitis.The geographical distribution of HCV genotypes can be quite complex,making it challenging to ascertain the most prevalent genotype in a specific area.Methods:To address this,a review was conducted to determine the prevalence of HCV genotypes across various provinces and as a whole in Pakistan.The scientific literature regarding the prevalence,distribution,genotyping,and epidemiology of HCV was gathered from published articles spanning the years 1996-2020.Results:Genotype 1 accounted for 5.1%of the patients,with its predominant subtype being 1a at 4.38%.The frequencies of its other subtypes,1b and 1c,were observed to be 1.0%and 0.31%respectively.Genotype 2 had a frequency of 2.66%,with the most widely distributed subtype being 2a at 2.11%of the patients.Its other subtypes,2b and 2c,had frequencies of 0.17%and 0.36%respectively.The most prevalent genotype among all isolates was 3(65.35%),with the most frequent subtype being 3a(55.15%),followed by 3b(7.18%).The prevalence of genotypes 4,5,and 6 were scarce in Pakistan,with frequencies of 0.97%,0.08%,and 0.32%respectively.The prevalence of untypeable and mixed genotypes was 21.34%and 3.53%respectively.Estimating genotypes proves to be a productive method in assisting with the duration and selection of antiviral treatment.Different HCV genotypes can exhibit variations in their response to specific antiviral treatments.Different genotypes may have distinct natural histories,including variations in disease progression and severity.Some genotypes may lead to more rapid liver damage,while others progress more slowly.Conclusions:This information can guide screening and testing strategies,helping to identify individuals at higher risk of developing severe complications.Studying the distribution of HCV genotypes in a population can provide valuable insights into the transmission dynamics of the virus.