This review provides a personal account of the explorations of a research group in oligosaccharide and glycoconjugate construction. The journey began twenty years ago with the study of Diels–Alder reactions of complex dienes. By extending this methodology to aldehydo‐type heterodienophile equivalents, access to unnatural glycals was gained (LACDAC reaction).
From this point a broad‐ranging investigation of the use of glycals in the synthesis of oligosaccharides and other glycoconjugates was begun. Mobilization of glycals both as glycosyl donors and glycosyl acceptors led to the strategy of glycal assembly. Several new glycosylation techniques were developed to provide practical underpinning for this logic of glycal assembly. Glycal‐based paradigms have been shown to be nicely adaptable to solid phase supported synthesis.
In crossing the desart of Shamo, they stop where water is to be found by a kind. Give notice of approaching noxious winds by stretching their necks, raising a cry. To yu # 4 some say is the same as Shayu } # the sand fish, or shark; others.
Moreover, glycal assembly—both in solution and on solid phases—has been used to gain relatively concise and efficient entry to a variety of biologically interesting and potentially valuable constructs. Some of these syntheses, particularly in the field of tumor antigens, have led to novel compounds which are in the final stages of preclinical assessment. This review presents an account of the chemical reasoning at the center of the program. Osmotr anesteziologa blank.
Domestic chickens ( Gallus gallus domesticus) fulfill various roles ranging from food and entertainment to religion and ornamentation. To survey its genetic diversity and trace the history of domestication, we investigated a total of 4938 mitochondrial DNA (mtDNA) fragments including 2843 previously published and 2095 de novo units from 2044 domestic chickens and 51 red junglefowl ( Gallus gallus). To obtain the highest possible level of molecular resolution, 50 representative samples were further selected for total mtDNA genome sequencing. A fine-gained mtDNA phylogeny was investigated by defining haplogroups A–I and W–Z. Common haplogroups A–G were shared by domestic chickens and red junglefowl.
60 zhash kuttuktoolor ir saptari. Rare haplogroups H–I and W–Z were specific to domestic chickens and red junglefowl, respectively. We re-evaluated the global mtDNA profiles of chickens.
The geographic distribution for each of major haplogroups was examined. Our results revealed new complexities of history in chicken domestication because in the phylogeny lineages from the red junglefowl were mingled with those of the domestic chickens. Several local domestication events in South Asia, Southwest China and Southeast Asia were identified. The assessment of chicken mtDNA data also facilitated our understanding about the Austronesian settlement in the Pacific. Introduction Being the most extensively distributed of the poultries, the domestic chicken ( Gallus gallus domesticus) provides humans with a stable sources of protein, including both meat and eggs (). The chicken has a long history of anthropomorphic usage in Southeast and East Asia, where it has been bred for entertainment (cockfight) and ornamentation ().
The domestic chicken also serves as an important model animal in biomedical research (). Although humans derive much benefit from this poultry, its history of domestication remains open to debate. Since the times of Charles Darwin (), the origin and domestication of chickens has attracted wide interest from multiple disciplines (; ). A massive amount of research has focused on reconstructing the matrilineal history of domestic chickens using mitochondrial DNA (mtDNA) sequence data. These efforts document that the red junglefowl ( Gallus gallus) is the primary wild ancestor of the domestic chicken (, ). The multiple, independent domestication events in southern China, South Asia and Southeast Asia involve several matrilines (; ). Most studies of chicken mtDNA rely on sequences of (partial) control region ( CR; D-loop: nucleotide position 1–1232; NC_007235).
The relatively small size of CR limits the resolution of the mtDNA phylogeny. Because the mutation rate in this region is higher than that in coding regions, high levels of recurrent mutations can blur the structure of the matrilineal genealogy. Recent, fine-gained analyses have used the complete mtDNA genome to reconstruct the history of animal domestication, such as in cattle (,; ), dogs (), horses () and pigs (). These updated phylogenies provide new insights into the origins and history of domestication.