| As the sole mammals capable of flying,bats(Chiroptera)have relatively diverse diet.In this paper,we made a comparative research on the digestive enzyme activity,small intestinal tissue structure and food retention time in five different diet bat species: Eonycteris spelaea(nectar-eating bat),Rousettus leschenaultii & Cynopterus sphinx(fruit-eating bat),as well as Hipposideros armiger & Myotis pilosus(insectivorous bat),and the main results were as follows:1.The activity of intestinal disaccharide enzyme in plant-eating bats(including nectar-eating bat and fruit-eating bat)was significantly higher than insectivorous bats(all P<0.05).Although all the five species of bats were of the activity of aminopeptidase detected in their small intestinal tract,in the insectivorous bats the activity was significantly higher than the plant-eating bats.The insectivorous bats appeared trehalase activity,but of all the plant-eating bats,only the Rousettus leschenaultii took on relatively low activity of trehalase.The activity of different enzymes were different between the species,as well as in the different sections of small intestine with,a basic trend of middle >front > posterior section.In a word,the digestive enzyme activity of small intestinal in bats was some certain related with their diets.2.The microstructure of small intestinal tissue in the five species of bats was similar to that of the other bats: lack of caecum.By the observation on tissue slices,we found that the small intestinal microstructure were also conposed of four layers including mucous membrane,submucosa,tunica muscularis and tunica adventitia.However,the length of villus,crypt depth,as well as the ratio between villus length and crypt depth(V/C value)of the five species were significantly difference(P < 0.05).The villus length of plants-eating bats was significantly higher than that of insectivorous bats,but the crypt depth of plants-eating bats was significantly lower than that of insectivorous bats(all P < 0.05).Insectivorous bats had significantly higher V/C value(all P < 0.05),and by two-way analysis we found that the V/C value was significantly difference between the different diet of bats(all P < 0.05).The results also indicated that different species of bats had different small intestinal villus height,crypt depth and V/C value.3.In this study,all the bat species were “Intermittent foragers”.However,the food retention time of plant-eating bats was significantly lower while longer intestine length than that of insectivorous bats,.All the above results indicated that the digestive enzyme activity was in accordance with the small intestinal microstructure to some extent.The plant-eating bats had slender small intestine,and higher V/C value,which signified plant-eating bats of having bigger intestinal mucosa surface area and possibly benefiting to the adhesion of digestive enzymes.Meanwhile,this would cause lower food transit time,thus the bats needed to be of high digestive enzyme activity(such as sucroase and maltase)to satisfy the demand of metabolism.Inversely,the insectivorous bats had short-and-wide small intestine,shorter villus,deeper crypt,lower V/C value and food retention time,which illustrated that the food of insectivorous bats was more impurities,and hard to digest.In addition,the activity of amino peptide enzyme was higher in insectivorous than in fruit-eating bats.Above the results showed that the small intestinal digestive enzyme activity,tissue microstructure and food retention time integratedly reflected the specificity in digestive functions and particularity in adaptive evolution for being of various diet bats.Also,these characteristic parameters intercoordinated with each other,and there was homoousia as well as some evidently differences or particularities,which indicated that the uniqueness of niche for bats likewise had the particular digestive physiological foundation. |
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