Native polyacrylamide gel electrophoresis have been applied for the analyses of alkaline phosphatase (<i>ALP</i>), malate dehydrogenase (<i>Mdh</i>) and malic (<i>ME</i>) isoenzymes in Arabian camel for racing and production. Two fractions for each of these isoenzymes have been recorded in the studied breeds. <i>ALP</i> showed very weak patterns without remarkable difference between the two breeds and this is an indication to that the samples used were healthy and being from the same age. The cytosolic <i>Mdh</i>-1 and <i>ME</i>-1 have been recorded in both camel breeds with high intensity. The mitochondrial <i>Mdh</i>-2 and <i>ME</i>-2 have been recorded with small intensity in production breeds commonly. The present data indicate the necessity of the mitochondrial<i>Mdh</i>-2 for energy production in racing breed and the responsibility of the cytosolic <i>Mdh</i>-1 for lipogenesis and energy production in both breeds. We therefore may assume that the appearance of both Mdh forms is necessary for both energy and lipid production in the production breeds while <i>Mdh</i>-1 was useful as bioenergetic enzyme necessary for racing. The different expressions are indications of the difference in the physiological adaptations of both camel breeds and are not for a systematic value

Malate dehydrogenase, α-esterase and β-esterase isoenzymes have been analyzed by native polyacryla-mide gel electrophoresis in different tissues (liver, kidney, muscle and hump) of the Arabian Camel, <i>Camelus dromedaries</i> in order to study the tissue specificity of these isoenzymes. Malate dehy-drogenase recorded three fractions while both este-rases recorded two fractions in different studied tissues. Malate dehydrogenase was considered as a key isoenzyme in discriminating among the different studied tissues. The percentage amount of both <i>Mdh</i>-1 and <i>Mdh</i>-2 showed significant difference among the different tissues while <i>Mdh</i>-3 recorded significant variation between muscle and hump tissues. The significant variation in the amount of <i>Mdh</i> isoenzyme (on the level of either total or fractions) among the different studied tissues may reflect the role of this enzyme for energy production in this desert animal. With respect to esterases, the percentage amount for both fractions and the total enzyme did not show significant difference among different tissues except <i>β-Est</i>-2 which was significantly higher in hump than in muscle. This enzyme showed higher thickness and intensity in both liver and kidney than in the muscle and hump indicating its greater activity in both liver and kidney

<span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">Three arbitrary chosen enzymes were examined by native-polyacrylamide gel electrophoresis to investigate physiologi</span><span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">cal and genetic variations among five different goat breeds inhabiting Saudi Arabia. The goat breeds were Pakistani, Tihami, Syrian, Masri and Aardi while the investigated enzymes were alkaline phosphatase</a> (<i>ALP</i>), malate dehydro</span><span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">genase (<i>Mdh</i>) and malic enzyme (<i>ME</i>). Six polymorphic loci with six monomeric alleles have been recorded in all stud</span><span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">ied breeds. The second locus of <i>ME</i> was characteristic of Syrian breed where it showed dimeric alleles. The similarity matrix that has been calculated according to the number of sharing bands indicated that these breeds have been divided into two groups: Pakistani and Tihami as one group while the other three breeds clustered in another group. The activity of the metabolic enzymes (<i>Mdh</i> and <i>ME</i>) showed concordance with the constructed relationship where the percentage amounts of these enzymes showed significant variations between the two groups more than that occurred within each group. <i>Mdh</i> was expressed in the second group more than </span><span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">in the </span><span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">first while <i>ME</i> showed, nearly, equal expression in the different breeds. Both genetic and physiological results agreed in clustering the studied breeds into Pakistani and Tihami in one group and the other three breeds in another group. This division was based on a few gene loci and a few sampling size and it needs to be supported by collecting more genetic data and more sampling size in a further molecu</span><span style="font-family:'Times New Roman','serif';color:black;font-size:10pt;">lar study.</span>

Native polyacrylamide gel electrophoresis have been used to analyze malate dehydrogenase (MDH), acid phosphatase (Acph) and peroxidase (Px) isoenzymes in different tissues (liver, kidney, muscle and heart) of the tilapia fish, Oreochromis niloticus in order to study the tissue specificity of these isoenzymes. Three, two and one fractions have been recorded respectively for the three isoenzymes in different studied tissues. The MDH-1 and MDH-2 have been expressed only in muscle and heart while MDH-3 has been expressed in all studied tissues. The percentage amount of MDH in general varied significantly between muscle and different studied tissues. With respect to acid phosphatase, the percentage amount of the total enzyme showed significant difference between liver and muscle and that this variation may be due to higher gene activity in liver. Peroxidase isoenzyme was recorded in liver and heart only with significant increase in liver. The kidney was the least among the studied tissues in showing gene expression for the studied isoenzymes and therefore, liver, heart and muscle tissues are better applicable in studying the isoenzymatic profiles for fish physiology and systematics.