Glucose absorption, carbohydrase activities, and carbohydrate hydrolysis and uptake in the intestinal tract of mature sheep

Carbohydrates are the predominant source of energy used to carry out the biological processes of growth, maintenance, and reproduction in the animal body. Glucose is the most important carbohydrate metabolite in both the nonruminant and the ruminant animal. In the non ruminant, glucose is also the most abundant end product of carbohydrate digestion. The nonruminant is able to utilize only traces of cellulose and hemicellulose as end products of microbial degradation in the large intestine, and the small intestine of this animal is the major site of carbohydrate assimilation. The microbiological digestion of carbohydrates makes the reticulo-nimen and to a lesser extent the omasum the major sites of carbohydrate assimilation in the ruminant animal. These microorganisms also degrade a portion of cellulose and hemicellulose to absorbable end products which can be utilized by the host animal. The rumen, being the major site of carbohydrate assimilation, has received the greatest attention by investigators of protein, fat, and carbohydrate utilization in the ruminant. Some research has been conducted in an attempt to determine the ability of the pre weaned ruminant to utilize certain carbohydrates. Little information is available in the literature regarding the digestion of carbohydrates and the absorption of glucose in the small and large intestine of the mature ruminant animal. In advanced pregnancy and during lactation an animal is in a critical glucose balance resulting from lactose synthesis (Armstrong, 1965). Since the major precursor of lactose is blood glucose (Reiss and Barry, 1953) supplied primarily through gluconeogenesis of noncarbohydrate sources (Armstrong, 1965), the importance of any glucose absorbed from the gastro-intestinal tract which would contribute directly to the maintenance of the blood glucose level is obvious. Although it is estimated that only about 10 percent of the glucose requirement of the ruminant animal is absorbed from the alimentary tract (Armstrong, 1965), it is of interest to know the efficiency of glucose absorption and utilization of other carbohydrates in the small and large intestine of the mature ruminant. The objectives of these studies were to determine; (l) the levels of the carbohydrases, maltase, lactase, sucrase, amylase, and cellobiase in the mucosa of the duodenum, jejunum, and ileum; (2) the rate of absorption of glucose in vivo in the duodenum, jejunum, ileum, cecum, and colon; and (3) the degree of utilization of maltose, starch, and cellulose in the duodenum, jejunum, ileum, cecum, and colon in mature sheep

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead