eChapters

An extraordinary variety of viruses, bacteria, and organisms stand ready to attack us and feed off our bodies’ cells. Using microscopes of varying power, photographers show us a teeming microbial world that we could barely imagine without their help.

INTRODUCTION

A parasite is an organism which exploits another organism for the purpose of staying alive. Some parasitic relationships are harmless, while in other cases a parasite can damage or even kill its host. The word is borrowed from the Greek word ‘‘parasitos’’, meaning “one who eats at the table of someone else.” In case of exotic carps parasites causes a great loss by reducing economy. Some, cannot live once their host dies, while others can continue thriving on dead hosts until their nutrients are consumed. Parasites live inside a host are called endoparasites or internal parasites. Ectoparasites live outside the host, and are generally more capable of switching hosts. A parasite preys on other parasites, is called epiparasite (Anderson, 1974).

Silver Carp

The silver carp (Hypophthalmichthys molitrix) is a species of freshwater cyprinid fish, a variety of Asian carp native to north and northeast Asia. It is cultivated in China. Pound for pound, more silver carp are produced worldwide in aquaculture than any other species. Silver carp are usually farmed in polyculture with other Asian major carps, or sometimes Indian major carps or other species. It has been introduced to, or spread into via connected waterways, at least 88 countries around the world.Introduced in india in 1959 at the pond culture division of CIFRI. In India in 1963 breed sucessfully by hypophysation. The silver carp is a filter feeder, and possesses a remarkably specialized filtration apparatus capable of filtering particles as small as 4 µm. The gill rakers are fused into a sponge-like filter, and an epibranchial organ secretes mucus which assists in trapping small particles. A strong buccal pump forces water through this filter. Silver carp, like all Hypophthalmichthys species, have no stomachs; they are thought to feed more or less constantly. Silver carp are thought to feed largely on phytoplankton; they also consume zooplankton and detritus. It is used in controlling water quality, especially control of noxious cyanobacteria (blue-green algae), microcystis .

Occasionally anglers catch fish that show signs of infection or parasitism. Is the fish safe to eat? The usual and safest response to this question is, “When in doubt - don’t.” However, very few fish diseases can be transferred to humans. Almost all fish are safe to eat when thoroughly cooked, smoked or frozen.

Fishes are a valuable resources for hill streams and temperate region people. Not only do they provide important recreation, but they are also a valuable supplement to the family food budget. The anticipation of any fisherman, whether he be a young boy with a cane pole and a can of worms or an “old pro,” is a quality fish for the table. It is the unwritten law of any true sportsman to utilize the fish he catches. The purpose of this publication is to help you, the angler, determine if the fish you’ve caught is worthy of your skillet. Remember, a sick fish will not take the hook (Taraschewski, 2000).

For most people in their right mind, parasites are disgusting little creatures. The mention of them evokes images of tiny crawlers entering the body of innocent victims by devious means, encrusting themselves within various organs (often with very unpleasant effects), living off their host’s tissues, and then exiting the body, sometimes through scatological avenues, leaving behind hosts that are incapacitated, if not mere shells of their former selves (as is literally the case for some insects). The true facts are not always that gruesome (after all, parasites that have to spend a long time inside a host do not benefit if this host kicks the bucket, because then they die as well) but often enough parasitic reality is not pretty. Ask biology students about their parasitology course, and they will tell you that attending class is like visiting a little shop of horrors. I, for one, came out of my parasitology course with newly developed phobias (mercifully temporary) of such innocuous activities as eating meat and bathing in streams – they represent ways of transmission for some parasites. But students will also tell you that parasites are fascinating because of the complexity of their life cycles and the intricate ways in which they complete these cycles. So fascinating, in fact, that many students eventually become parasitologists and devote their entire lives to studying the little critters. Most of these people work with parasites of livestock or humans, but a few with an equal taste for ethology and ichthyology pursue the more esoteric questions that occupy this page: how fishes avoid getting parasitized, and how fishes alter their behaviour once they get parasitized (Barber et al., 2000)

INTRODUCTION

Zoonoses are diseases and infections which are naturally transmitted between vertebrate animals and humans. The pathogens that cause zoonotic diseases are bacteria, fungi, viruses, parasites or protozoa. Disease transfer occurs via direct or indirect exposure to the pathogen. A pathogen is contracted directly through skin to skin contact of an infected animal or through ingestion of diseased animal products (infected faeces, urine, saliva, blood, milk or other bodily fluids). A bite or sting from a diseased animal or through an infected invertebrate host directly transfers the pathogen to humans as well. Indirect exposure occurs through air, water or soil in which the pathogen can survive for a limited period of time without a host ( Acha, et al., 2003).

CLASSIFICATION OF ZOONOSES

The World Health Organization (WHO) Expert Committee on Zoonoses came up with the following classification system of zoonoses based on the type of life cycle of the pathogen.

INTRODUCTION:

An association of two organisms, one living at the expense of other for food and shelter is called parasitism. Parasite factors associated with recognition and selection of the host and the mechanisms in the host responsible for acceptance or rejection of the invading organism were evaluated. Sensory structures in parasites are able to detect differences between different fish species and this ability to discern between fishes may be based on both chemical and mechanical stimuli on the host surface. Complex glycoproteins, proteins, carbohydrates and simple molecules attract parasites or modify their behaviour. (Kurt Buchmann and T. Lindenstrom, 2002)

INTRODUCTION

It can be added that physiological stress as well as the physical offences contribute as primary factor for disease occurrence and fish mortality. Many parasitic diseases due to fluctuation in water quality leads to deplition of stock, and some times total stock will go eg. yellow grub disease.

EFFECT OF TEMPERATURE ON PARASITES

Heterophyid Trematode

Cyprinodon variegatus, an estuarine fish, is heavily parasitized in the bulbus arteriosus by the heterophyid trematode Ascocotyle pachycystis. Parasitized fish ventricles were hypertrophied due to mechanical blockage of normal blood flow by metacercariae in the bulbus Swimming performance generally was reduced by the presence of parasites, which had their most significant negative effect at cold temperatures and low dissolved oxygen level ( Felicia C. Coleman , 1993)

PREVENTION

This section will discuss ailments that affect the fish kept in our aquariums. We will simply not call them diseases because most are not true diseases but a response to some sort of stimuli such as poor tank water management or the presence of actual parasites. A list of the most common ailments, the reasons behind them and the appropriate action needed to “fix” the problem is given in this Chapter.

If you maintain good water quality, keep the right kind of fish together, feed good quality food and monitor all your water properties you will rarely have any problems. A few common sense precautions when you purchase new fish can save you a lot of trouble.

INTRODUCTION

Fish culture as a hobby or business is well established in India. Increased interest in fish culture has also increased awareness and experience with parasites that affect fish health, growth, and survival. Information provided in this chapter is intended for the novice fish culturist as a guide to common parasites of freshwater fish. Identification of parasites and their basic treatment is included; however, any herbal treatment alone or biological cum chemical treatment may be choosen for eradication purpose (Das et al., 1995a).

WHY, WHEN AND HOW FISH GET PARASITES

Parasites pose a real risk to fishes

All fish are potential hosts to many different species of parasites. Small numbers of parasites are common and probably do little harm. However, all parasites have tremendous reproductive potential and can, under ideal conditions, quickly overwhelm fish in the confines of a tank or pond.

Types of parasites

We can broadly class parasites into two groups. Ectoparasites are found on the external surfaces such as skin, fins and gills, while endoparasites are found in the internal tissues and organs.

Endoparasites are uncommon in ornamental fish. However, there is a wide diversity of blood parasites, worms that colonize the intestines and other parasites that can invade various organs and tissues. Many require an intermediate host, such as snails, birds or the introduction of an infected fish, and so are rare in pond/ aquarium fish. There are a variety of clinical signs which might indicate the presence of endoparasites. Lethargy accompanied by emaciation is a common sign, as are worms protruding from the anus. Identification of sporozoan and protozoan endoparasites often requires microscopic examination of tissues (Chanratchakool et al. 1994).

The Distributed Information Sub Center at Kerala Agricultural University, Thrissur was set up in May 1995 as the 23^rd center of the BTISNet of DBT, Government of India. The area of specilisation of the Centre is Agricultural Biotech- nology. The Centre passed through several phases involving Internet connectivity through the ordinary C band connectivity, then the Ku band connectivity etc. Now the commu- nication facilities of the Centre have been strengthened by procuring an ISDN Internet connection and a connection through ASIANET. The Center caters to the needs of the students (UG, M Sc & Ph D) and faculty of all departments of the Colleges in the main campus as well as of the other nearby academic and research centers of the University. Over the years, DISC has come to occupy a position in the KAU in the area of Infor- mation Technology , information sources and services based on Internet, CD-ROMs etc. The Centre has procured databases in the field of Biotechnology and developed several databases in the field of Agriculture and related fields. The center regularly conducts training programmes in Bioinformatics. The research activities in the field of Bioinformatics have been enhanced. The Centre has now been upgraded to DIC to facilitate intensive research on Bioinformatics in an effective manner. During the year 2004, the Centre has also started offering a course on Bioinformatics for the M.Sc Biotechnology students of the College of Horticulture.

Biotechnology research in KAU spread over various research stations and cam- puses includes Plant Biotechnology, Animal Biotechnology and Fisheries Biotechnol- ogy. Thrust areas for Plant Biotechnology include developing in vitro protocols for mass multiplication of elite types of fruit plants, ornamentals, medicinal plants, spices, plantation crops and forest species. The other thrust areas include checking clonal stability and genetic fidelity of in vitro derived plants using molecular markers, DNA finger printing and characterisation of germplasm with molecular markers, imparting biotic and abiotic stress tolerance in otherwise accepted crop varieties, genetic trans- formation for imparting/ improving expression of desired traits, in vitro germplasm conservation, enhancement of secondary metabolites production etc.

The crops identified for biotechnology research at KAU include spice crops like black pepper, ginger, turmeric, vanilla, cardamom; plantation crops like cashew, coco- nut and medicinal & aromatic plants such as Kaempferia, Trichopus, Gymnema, Holostemma and Coscinium. For improvement of such crops through molecular breed- ing, it is highly essential to identify/design specific probes/primers, micro-satellites, etc. By combining the research results generated at the Biotechnology Centre and informa- tion retrieved from the Bioinformatics Centre, suitable probes, primers are being de- signed for characterization and improvement of these unique crops through molecular breeding.

ABSTRACT

The Cry2A proteins are promising candidates for managing the development of Cry1Ac resistance in insects. The Cry2A class of proteins is different from that of Cry1A, and experiments have shown that insects resistant to Cry1Ac are not cross-resistant to Cry2A proteins. However, the Cry2A proteins are less toxic than Cry1Ac to the polyphagous pest Helicoverpa armigera. Structure-based protein engineering of Cry toxins may pave the way for directed evolution of variants with broad spectrum of insect species specificity, enhanced potency, and stability. In the present study homology modeling of Cry2Ac was done using DeepView software. The template for Cry2Ac protein sequence (accession number X57252) was selected using ExPdb template search. The raw sequence of the Cry2Ac was superimposed over the Cry2Aa PDB template (1I5P). The superimposed model was submitted to the SWISS Model server. After receiving the Cry2Ac model, energy minimization was done using Gromos96. The threading energy and force field energy were calculated. The homology model of Cry2Ac made by us along with the Cry2Ac model from the SWISS-MODEL Repository was used for comparative analysis of receptor binding regions of Cry2Aa. Results showed variation between the two highly homologous Cry2A proteins in their receptor binding regions which may account for differences in spectrum of insecticidal activity.

ABSTRACT

Astudy was undertaken at Department of Soil Science & Agrl. Chemistry, College of Horticulture, Vellanikkara to standardize different amelioration techniques to prepare enriched coirpith compost. Twelve treatments were tried using different combinations of coirpith, Pleurotus spp., Schizophyllus spp., urea, rock phosphate, cowdung slurry, mushroom waste, goat manure, glyricidia and water hyacinth. The results of the various enrichment techniques revealed that the temperature in the compost in general, increased to a peak value of 47oC on the 22nd day of composting and later decreased to a stabilized value. The observed temperature of 40-50 °C found during the thermophilic stage is essential for the rapid degradation of lignocellulose, as the thermophilic microfungi and actinomycetes involved in this process thrive at that temperature. Though the pH show a hike at the initial stage of composting, it decreased and stabilized at the later stage of composting which is conducive for growth and proliferation of microbes. The treatment coirpith with Pleurotus spp., glyricidia +20% cowdung slurry and goat manure was found to be ideal for compost preparation.

ABSTRACT

Biological lipids are chemically diverse group of compounds. Lipids serve two major biological roles namely a structural one as component of membrane, and storage function, particularly in certain seed tissues. Fats and oils are the principal stored form of energy in many organism, and phospholipids and sterols makeup about half of the mass of biological membranes.

An experiment was conducted to study phospholipids composition qualitatively as well as quantitatively in the roots of mung bean seedlings. Among the four solvents used for phospholipids isolation, solvent II (methanol) and solvent III (chloroform: methanol: NH₃ salt) were proved to be the major phospholipids eluting solvents. The results indicated that Phosphatidyl Choline (PC), Phosphatidyl Inositol (PI), Phosphatidyl Serine (PS), Phosphatidyl Ethanolamine (PE) and Di Phospho Glyceride (DPG) were present in significant amount in the roots of ten days old mung bean seedlings. These phospholipids were also identified by their Rf values using thin layer chromatography. Among all the phospholipids isolated, PI showed the minimum Rf value, whereas PS showed the maximum Rf value. On the basis of column chromatography, four fractions of phospholipids were isolated. The highest amount of phospholipids was found in fraction II and the lowest in fraction I. Fraction II and fraction III contained the maximum phospholipids. In the fraction II PC showed the highest content (μg g-1) and one unidentified phospholipids showed the lowest content (μg g-1), whereas in fraction III, PI showed the maximum content (μg g-1) and PS showed the minimum content (μg g-1).

ABSTRACT

The potato is one of the most important food crops both in developed as well as in developing countries. Developing countries today produce 37 per cent of world’s output of potatoes. Potato is an important food crop in India. Both area under potato cultivation and production has increased manifolds during past decades. The efforts are being made to improve potato quality and its post harvest life as well.

An experiment was conducted to isolate mitochondria from potato tubers and succinate dehydrogenase (SDH) assay and protein profiling were performed in the tissue. Three varieties namely, Kufri Bahar, Kufri Lauvkar and Kufri Jyoti were taken into consideration for the present investigation. Kufri Bahar showed the minimum values for SDH activity and Kufri Jyoti the maximum SDH activity. On the basis of SDH activity, the mitochondria in Kufri Jyoti were seemed to be more viable, functional and coupled as compared to Kufri Bahar and Kufri Lauvkar. This finding also suggested that the respiratory degradation of starch in Kufri Jyoti was higher as compared to Kufri Bahar and Kufri Lauvkar. Thus these result showed that the shelf life of Kufri Jyoti was less as compared to Kufri Bahar and Kufri Lauvkar. Protein profiling performed by SDS-PAGE was found to be similar in all the potato tubers.

ABSTRACT

Apot culture experiment was conducted on tomato with cadmium and lead to identify the selective retention sites of the metals. For this a completely randomized design with five treatments and four replications were laid out at the College of Horticulture, Vellanikkara. The different levels of treatment ranged from 0.5 to 2.0 mg kg -1 soil. Cadmium and lead were directly supplied as a water-soluble source through cadmium chloride and lead nitrate respectively. In tomato the growth and fruiting was permitted only at lower levels of cadmium application. At 1.5 mg kg-1 soil, fruiting failed. While at 2.0 mg kg-1 soil, the very establishment of plant was totally affected. At higher levels of application, cadmium preferred to get accumulated in roots while on the contrary at lower levels, cadmium uptake increased in shoots than in roots with the least content of the metal in fruits. However, in the case of lead, all levels of application in soil permitted growth and fruiting. With increase in rate of lead application, significant selective retention was observed in roots (1.48-6.69 ppm), shoot (0.29-1.62 ppm) and fruits (0.39-1.45 ppm). On comparison of retention sites of lead in tomato, it could be seen that fruits maintained the maximum lead uptake (637.2-2933.0 mg pot-1). Hence, the consumption of such tomato fruits contaminated with heavy metals may result in kidney damage, lack of memory, dissolution of phosphorus in the bones etc.

ABSTRACT

Detection of disease tolerance with enhanced defense mechanism is a practical approach in crop variety improvement programme. Toxins being responsible for pathogenicity and virulence of the fungi, regenerating plants from toxin treated calli is an effective and easy approach. The response of tomato calli to the crude toxins of the foliar pathogens viz., Alternaria solani and Septoria lycopersici was studied and the changes in phenol metabolism due to toxin treatment were analysed. Crude toxins of A. solani and S. lycopersici extracted under optimum conditions were serially diluted and tomato calli were treated with different dilutions of the toxins to find out the optimum dilution at which minimum survival percentage was obtained, based on a 1-4 score. Minimum score of 1 was obtained at 1:10 dilution for A. solani and at 1:20 for S. lycopersici.

The calli of resistant (LE-625) and susceptible (CO-3) tomato varieties were treated with desired dilutions of the toxins of A. solani and S. lycopersici. Total phenolics and ortho- dihydroxy (OD) phenolics were estimated at 24 h interval to study the extent of necrosis on resistant and susceptible calli due to toxin treatment. The total and OD-phenol contents of calli of susceptible cultivar (CO-3) progressively decreased with increase in time interval consequent to the treatment of toxins of A. solani and S. lycopersici. In the resistant calli of LE-625, an initial reduction of total phenol and OD-phenol content was observed following the application of the toxins of A. solani and S. lycopersici at 24 hours after treatment. Later with lapse of time, the total phenol content and OD-phenol contents progressively increased reaching a maximum at 120 h after treatment. The results clearly indicated the enhancement of biochemical defense in the resistant calli and a fall in defense mechanism in the susceptible calli due to toxin treatment. Such techniques are useful in the preliminary screening of resistant genotypes in crops like tomato.

ABSTRACT

In Kerala, apart from cultivated sesame species (Sesamum indicum L.) three wild species were identified viz. Sesamum malabaricum, Sesamum mulayanum and Sesamum radiatum. An investigation was carried out to determine the intensity of arbuscular mycorrhizal fungal colonization in cultivated and wild species of sesame. The percentage of arbuscular mycorrhizal fungal infection in roots of different sesame species were found to be variable. The highest percentage of root colonization of arbuscular mycorrhial fungi was found in wild species S. malabaricum, which promotes tolerance to the plant under drought stress conditions.

ABSTRACT

Atotal of 45 Gram positive, spore forming and rod shaped bacteria identified as Bacillus species were isolated from the rhizosphere of Chickpea plants. They were studied for their interaction with root borne fungal pathogens was studied using spot test method. Isolates CBS 29, CBS 113, CBS 123, CBS 132, CBS 153 and CBS 155 inhibited the growth of four or more fungi with inhibition zones varied from 1-5 mm. Two isolates CBS 153 and CBS 155 produced siderophores on CAS supplemented agar medium. Further inoculation of these Bacilli on seeds of Chickpea cultivar C235 and H8618 showed inhibitory, stunting or stimulatory effects on plumule and radicle growth depending upon cultivar, bacterium used and stage of seedling growth. Studies on co-inoculation of these isolates with Mesorhizobium and their plant growth promoting activity are being carried out. These co-inoculation studies are important areas of exploitation to improve crop productivity.

ABSTRACT

Black pepper (Piper nigrum L.), known as the ‘King of Spices’ is an important export- oriented spice crop, valued for its medicinal and condimental properties. A perfect protocol for the rapid in vitro multiplication of this plant is available. However, systemic bacterial contamination is the single major constraint in the large scale in vitro production of plantlets. Based on morphological and biochemical characters, this bacterium was identified as Beijerinckia indica It grows profusely on nitrogen-free Jensen’s agar and solubilizes CaCO in the medium by acid production. It is resistant to a range of antibiotics and produces indole acetic acid. The bacterium is slow growing and has pH optima of 5.5 and temperature optima of 27oC. It has both endophytic as well as epiphytic association with the plant, the colonization being more in the stem and petiole. A single plasmid of 4.0 kb size was isolated from the bacterium and characterized. Competent cells of E. coli DH5a, transformed with this plasmid survived on Jensen’s nitrogen free agar, indicating its ability to fix atmospheric nitrogen. We stipulate that the nif genes are located on the plasmid of the bacterium. Since endophytic bacteria are known to stimulate plant growth through antagonistic activity against pathogens, production of growth promoting substances and inducing systemic resistance in several other agricultural crop species, the symbiotic association between Bejerinckia indica and black pepper could be further exploited through integrated nutrient management for improved growth and yield of this spice crop.