eChapters

1.    The organic molecules which increase the rate of metabolic reactions are referred as

(a) Coenzymes

(b) Enzymes

(c) Reactants

(d) Apoenzymes

2.    Enzymes are

(a) Organic compounds produced by living organism

(b) Inorganic compounds

(c) Both (a) & (b)

(d) None of these

ENZYMES

Enzymes are the heart of Biochemistry

Protein based catalysts.

Enormously effective catalysts: typically enhance rates by 10⁶ to 10¹² fold.

Operate under mild conditions: 0 - 100 °C (or perhaps even 300+ °C for some bacteria in deep ocean), 20 - 40 °C for most organisms; and low pressures (atmospheric).

Very specific: Generally catalyze reaction for a very restricted group of molecules, sometimes for a single naturally occurring molecule of a single chirality.

1. INTRODUCTION

Enzymes are proteins with highly specialized catalytic functions responsible for many essential biochemical reactions in microorganisms, plants, animals and human beings. Enzymes play an important role in many aspects of life since the dawn of civilization that have used enzymes for thousands of years without understanding what they were or how they work. Food processing through the use of biological agents/enzymes is historically a well-established approach. The earliest applications go back to 6000 BC or earlier, with the brewing of beer, bread baking, cheese and wine making. Whereas the first purposeful microbial oxidation dates back 2000 BC, with vinegar production. In the late 19^thcentury, Christian Hansen reported the use of rennet for cheese making and production of bacterial amylases was started at Takamine (latter became part of Genencor). Pectinases have been used for juice clarification in the 1930s and during World War II, invertase was also employed the production of invert sugar syrup in a process that pioneered the use of immobilized enzymes in the sugar industry. Still, the large-scale application of enzymes could only be really established in the 1960s, when the traditional acid hydrolysis of starch was replaced by an approach based in the use of amylases and amyloglucosidases (glucoamylases) and glucose (xylose) isomerase. From then onward, the trend for the design and implementation of processes and production of products by the use of enzymes has steadily increased.

Food and beverages and household care industries represent the largest application areas of enzymes, followed by animal feed, biofuels, textile and other technical industries. Recently, several new developments have taken place in the application of enzymes in fruit and vegetable processing. Fruits and vegetables are consumed as fresh or processed into different type of products. Commercial enzyme preparations are used as processing aids in fruit and vegetable processing to improve the process efficiency and product quality, because enzymes show activity on specific substrates under mild processing conditions. Therefore, there has been a striking growth in the enzyme market for applications in the fruit and vegetable industry.

Enzymes are biocatalysts that change the rate of reaction without being changed themselves. All (Most) enzymes are proteins but all proteins are not enzymes. Ribonuclease is the enzyme which is non- protein in nature.

Properties of Enzymes

Enzymes are organic catalysts produced by living organisms. They make possible biochemical reactions. Hence they are called biocatalysts. They are mostly a specialized class of proteins. However, there are some non-protein enzymes like ribozymes, which are RNAses. Enzymes speed up reactions at ambient temperatures. This is in contrast to chemical reactions like saponification of lipids which take place when lipids are boiled for a few hours with concentrated alkali.  Enzymes, namely, lipases, hydrolyze lipids at body temperatures in minutes. They are superior to chemical catalysts by a factor of 107 to 1014 .  An enzyme may be a simple protein or a complex protein. They are produced by cells and are mostly globular proteins. Each cell contains an estimated 3000 different enzymes.

Enzymes are biocatalysts that play a crucial role in accelerating chemical reactions without undergoing any changes themselves. Enzymes enhance the rate of a reaction by reducing its activation energy without affecting the equilibrium position of the reaction. These catalysts specifically target molecules called substrates and convert them into different molecules known as products. Most enzymes have a proteinous nature, and some have a ribonucleic acid nature (like ribozymes and peptidyl-transferase), showing high substrate and stereo-specificity. Enzyme catalysis is indispensable for the majority of metabolic processes in cells, as it ensures that these processes occur at a rate that is sufficient to sustain life. The progression of metabolic pathways heavily relies on the catalytic activity of enzymes to facilitate individual steps.

The proteinous enzymes are classified into simple and conjugated enzymes.

1. Simple enzymes: Enzymes are made up of only protein components.

2. Conjugated enzymes: Enzymes comprise both protein (apoenzyme) and non-protein components (cofactor).

The term enzyme was coined in 1878 by Friedrich Wilhelm Kuhne to designate these biological catalysts that had previou-sly been called ferments. As they quicken most of the chemical reactions occurr-ing in the body, the enzymes have been designated as the “manifestations of nature’s impatience”.

Feed accounts for a significant cost of production in livestock and poultry. In case of poultry, it represents 65% cost of the production in broilers and 75% in layers. Presently the live stock industry faces a huge challenge due to the high cost of feed ingredients and shortage of the conventional feed ingredients. Over the years, efforts have been made to use unconventional feed ingredients. However, such feed ingredients have many anti nutritional factors that adversely affect the performance of livestock and poultry. Due to the presence of these incriminating factors, the unconventional feed ingredients are poorly digested in livestock and poultry. These poorly digested feed ingredients results in bacterial overgrowth, which becomes a potential substrate for bacterial fermentation leading to intestinal disorders and disease. Application of antibiotics and other anti-microbials help to overcome the ill effects. However, the ban on the use of sub therapeutic level of antibiotics in many countries has increased the relevance of use of exogenous enzymes in the feed of livestock and poultry. These exogenous feed enzymes improve the nutritive value of different feed stuffs, economize livestock and poultry rearing and reduce environmental pollution.

Enzymes are organic catalysts produced by living organisms. They make possible biochemical reactions. Hence they are called biocatalysts. They are mostly a specialized class of proteins. However, there are some non-protein enzymes like ribozymes, which are RNAses. Enzymes speed up reactions at ambient temperatures. This is in contrast to chemical reactions like saponification of lipids which take place when lipids are boiled for a few hours with concentrated alkali. Enzymes, namely, lipases, hydrolyze lipids at body temperatures in minutes. They are superior to chemical catalysts by a factor of 10⁷ to 10¹⁴ . An enzyme may be a simple protein or a complex protein. They are produced by cells and are mostly globular proteins. Each cell contains an estimated 3000 different enzymes.

Etiology

It is a relatively rare skin disease or dermatologic condition. Hypersensitivity reaction is one of the suggestive cause for this condition characterized by nodules or plaques which are seen in the skin, oral mucosa and external ear canal.

INTRODUCTION

In India, medicinal plants have traditionally occupied an important place in the socio-cultural, spiritual and health related aspects of peoples’ life. As much as 34% (ca. 6000) of total plant wealth have some known medicinal value (Ved, 2008). The genus Ephedra is one such important group of medicinal plants, from which the drug Ephedrine and a range of medicinally active compounds such as ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methyl ephedrine, methyl pseudoephedrine, alkaloids, phenols, terpenoids are obtained. Owing to its medicinal properties, genus Ephedra is in high demand by pharmaceutical industries. It is currently facing heavy extraction pressure from its restricted habitat in the wild, and utterly lacks effective proper conservation and management efforts. For long-term conservation management of this genus, a better and comprehensive understanding of the species remains a top priority, for which detailed studies on its biology, habitat ecology, and agro-technology are required.

Veterinary epidemiology is the study of disease within a livestock population, dealing with the investigation (including identification, quantification, and examination), of the direct and indirect determinants of disease distribution in animal populations. Any epidemiological investigation starts with whether there is an animal health problem in a population, which requires data collection on animal, management, economic, and environmental factors. These data are then analyzed descriptively to assess the frequency of disease occurrence. The results are then used to decide whether investigations of causal relationships between disease occurrence and potential risk factors are necessary for the development of control or prevention policies. Once the relationships are understood, necessary interventions for the disease are then planned and their impacts assessed. Hence, the goal of epidemiological investigations is the control and prevention of animal disease problems by integrating the available pieces of evidence into the decision-making process for disease control policy development.

True/False

Q.1.    The purpose of most medical research is to identify the causes of disease and search out the ways to prevent or cure them.
Q.2.    Now a day, epidemiology has become a basic science for public health
Q.3.    The studies of diagnostics therapeutic and prognostic procedures have successfully incorporated into growing stream of “Clinical Epidemiology”.

Epidemiology is the study of diseases in a population in its natural setting. In epidemiology, the population is the patient and hence epidemiology is population medicine. All epidemiological studies are field based. In aquatic epidemiology, aquaculture ponds serve as the laboratory. This can be a great advantage over laboratory studies, which cannot be easily extrapolated to field conditions.

Diseases are among the greatest deterrents to the sustained production in aquaculture. Diseases such as Epizootic Ulcerative Syndrome (EUS) in fishes and White Spot Syndrome (WSS) in shrimps have devastated aquaculture with bad impact on productivity and profitability. Various diagnostic and health management tools are being used to devise disease control strategies. It is becoming increasingly difficult to manage pathogens that have become endemic. Epidemiological approaches which have been very successful in human and veterinary medicine are now being increasingly recognised as important weapons that can be used in aquaculture to formulate disease control programmes.

Concept of Cause for a Disease

Cause from an epidemiological perspective is interpreted in quite a wide sense. This is somewhat different to the more traditional view of the role of cause being restricted to etiological agents. An epidemiological definition of a cause of a disease is “an event, condition or characteristic that plays an essential role in producing an occurrence of the disease”. Epidemiologists avoid defining the word cause for any disease outbreak, but prefer to use words such as determinants, exposures and risk factors. Alternatively, they will categorise causes as direct or indirect; necessary or sufficient; and single or multiple rather than defining primary etiology.

Epidemiology

Vanderplank has called epidemiology the science of disease in population. Epidemiology puts its emphasis on population phenomena. The important populations are those of the host, on the one hand, and of the pathogen, on the other. But further, epidemiology is concerned with host-pathogen interactions that lead to disease and crop losses. These interactions are often environmentally dependent. So epidemiology deals with effects of the biotic and abiotic environments. Finally , man has had important effects on hosts, pathogens and the environments, effect that today are increasing in magnitude and scale of importance. Epidemiology therefore also deals with the effects of man on disease and sometimes with the effects of plant disease on mankind. All of this can be symbolized by the disease tetrahedron.

1 Study of distribution of diseases and the factors determining its distribution in a population is known as

a) Ethology b) Epidemiology

c) Ecology d) Etiology

Introduction
The science of epigenomics has emerged as a key area of research across numerous biological disciplines. Epigenomics is the analysis of epigenetic changes occuring across many genes in a cell or entire organism, whereas the concept of epigenetics focuses on processes that regulate how and when certain genes are turned on and turned off. Understanding on the science of epigenetics can be traced back to the early hypothesis proposed by Aristotle to disprove the theory of preformation. Waddington’s initial conceptualization of epigenetics as a “conceptual tool” to integrate genetics and embryology established a foundational framework for subsequent research. Over time, advancements in molecular biology, developmental biology and evolutionary biology have since profoundly expanded and refined our understanding of epigenetics. Waddington further progressed in the 20th century with his introduction of the “Epigenetic Landscape” model (Baedke, 2013), marking a crucial milestone in the evolution of epigenetic theory.
In modern times, epigenetics refers to the study of heritable changes in gene expression or cellular phenotype that do not involve alterations to the underlying DNA sequence. Recent genetic and biochemical research has improved the understanding of various epigenetic regulation by three mechanisms including DNA methylation, histone modifications and non-coding RNA regulations. These mechanisms induce changes in chromatin conformation (active-open or repressiveclosed), which influences the gene expression that results in gene activation or gene silencing (Fig.1).
The transition between open and closed chromatin states, along with interactions among various epigenetic mechanisms, is essential to maintain optimal cellular function in diverse cell types, tissues and in response to varying developmental or environmental stimuli (Allis and Jenuwein, 2016).
Extensive studies in Arabidopsis led to a profound understanding of epigenetic mechanisms in plant growth and development. Later, intensive investigations was

7.1 Summary

Climate change is a complex global phenomenon that poses significant challenges for agriculture including uncertainty about future weather patterns, soil conditions, and other environmental factors. Farmers are facing the difficult task of interpreting and responding to these changes in order to maintain their livelihoods and ensure food security for growing populations. In this context, mental modelling has emerged as a useful approach for understanding how farmers interpret and respond to climate change. Mental models are cognitive representations of how individuals understand and make decisions about complex systems, and can be used to identify key drivers of behaviour and decision-making.

The present study has explored the social, ecological, and economic factors that influence farmers’ mental models on perception of climate change, level of uncertainty and trend of agricultural change in the selected study area. It argues that farmers’ mental models are shaped by a range of factors, including their own experiences and observations, social networks and interactions, access to information and resources, and broader economic and political contexts. The present study has also highlighted the role of uncertainty in shaping farmers’ mental models and decision-making. Uncertainty about the future impacts of climate change can create significant challenges for farmers, as they must make decisions based on incomplete information and uncertain predictions.

The current research work was carried out in the new alluvial zone which is one of the agro-ecological regions in the state of West Bengal. To conduct the study, three villages located in the Haringhata block of Nadia district were chosen randomly. A total of 90 farmers were selected with 30 respondents each from the villages of Kastadanga, JalkarBhomra and Subuddipur. Initially a list of contact farmers was collected from the Kastadanga SKUS and few contact farmers were selected randomly from the list. Afterwards Snowball sampling method was followed to select respondents.

Bhuva is a small village in north-west Gujarat – India.  My mother was born there. The loving people of Bhuva called me ‘Bhano’ (Sister’s Son / Nephew) and it was my favourite place to go as a child. I have my fondest memories of Bhuva, but could not visit for several decades, until when I was once at the Junagadh Campus of Gujarat Agricultural University, to inaugurate the International Conference on New Developments in Agriculture. Bhuva was not too far and I decided to go there. Soon as I reached, a familiar face, now aged with time, recognized me from a distance and with tears rolling from his old eyes (and mine) he hugged me, calling out “MaroBhano, MaroBhano” (My sister’s son, my sister’s son)! Now in his eighties, it was overwhelming to meet Nanji Ata, who I always remembered being wise, educated and cheerful. He was a relatively progressive farmer with about 6 to 7 acres of land, a few cows and a buffalo. Though water was scarce and saline, he managed to make a good living and was considered a well to do man.