The origin of melezitose: a biochemical relationship between the lime tree (Tilia spp.) and an aphis (Eucallipterus tiliae L.)

Abstract

CARBOHYDRATE METABOLISM OF SKIN 289 cluding citrate, a-oxoglutarate, succinate, fumarate and malate, only glucose, fructose, lactate and pyruvate produced maximal mitotic activity over 4 hr. in mouse-ear skin in vitro. The effects of glucose 1-phosphate are difficult to interpret without further experiments to determine the fate of the compound. Barron et al. (1948) and Griesemer & Gould (1954) found citrate to have no effect upon skin respiration. Barron et al. also failed to demonstrate i80citric dehydrogenase in skin and found no stimulation on the addition of a-oxoglutarate. On these grounds they suggested that the citric acid cycle in its classical form did not operate in skin. Our results, which show a sharp contrast between the obvious usage of succinate, fumarate, malate and oxaloacetate and the transient usage of citrate and nonutilization of a-oxoglutarate, are consistent with their findings, but the evidence is as yet insufficient to conclude that skin differs in its oxidative processes from the majority of other tissues. SUMMARY 1. The respiration and glucose utilization of skin of the guinea-pig ear in vitro are unaffected by the glucose concentration within the range 0005-0*02M. 2. The respiration and fructose utilization increase as the fructose concentration is increased. 3. In glucose-fructose mixtures the utilization of fructose is reduced, the glucose utilization is unaffected and the total hexose utilization thus increases. This is not reflected in an increased respiration rate. 4. Inthe absence ofserumthe glucoseutilizationis only about one-half of that occurring in the presence ofserum, and the respirationis only slightlyreduced; the sum of lactic acid produced and the calculated glucose oxidized equals the observed glucose utilized. 5. Glucose, fructose, lactate and pyruvate stimulate respiration and maintain a relatively high respiration rate for 24 hr. 6. Succinate, malate and acetate stimulate respiration but permit a gradual decline over 24 hr. 7. Oxaloacetate maintains respiration for 5 hr. only, subsequently becoming toxic; fumarate also stimulates respiration initially but its effect declines between 5 and 24 hr. 8. Citrate causes transitory stimulation in the first hour and o-oxoglutarate is without effect. 9. Glucose 1-phosphate causes initial depression, but at 24 hr. a slight increase over the control occurs. 10. These findings are discussed in relation to the carbohydrate metabolism of skin.

Metabolism of Four α-Glycosidic Linkage-Containing Oligosaccharides by Bifidobacterium breve UCC2003

“…] is an ␣-glucose-containing trisaccharide found in honeydew and manna, which are sugar-rich liquid and solid deposits, respectively, associated with the leaves and branches of various trees and shrubs (32). Although it was initially believed that melezitose was an oligosaccharide that was naturally present in various plants (33), it was later concluded that certain insects are responsible for melezitose production, since this sugar is absent from the tree sap used by such insects to form honeydew (32).…”

Transcription of Two Adjacent Carbohydrate Utilization Gene Clusters in Bifidobacterium breve UCC2003 Is Controlled by LacI- and Repressor Open Reading Frame Kinase (ROK)-Type Regulators

“…It was initially hypothesized that melezitose is an oligosaccharide that is naturally present in various plants (28). However, it was later found that certain insects are responsible for melezitose production, when they use carbohydrates present in tree sap, by itself devoid of melezitose, to form honeydew (27). In the current work, we investigated the transcriptional regulation of the gene clusters associated with the metabolism of the raffinose family sugars and melezitose.…”

“…The raf locus in the B. breve UCC2003 genome is located adjacent to the mel gene cluster, which allows the strain to metabolize the trisaccharide melezitose [␣-D-Glcp-(1¡3)-␤-D-Fruf-(2¡1)-␣-D-Glcp], found in honeydew and manna, which are sugar-rich liquid and solid deposits, respectively, associated with leaves and branches of various trees and shrubs (20,27). It was initially hypothesized that melezitose is an oligosaccharide that is naturally present in various plants (28).…”

Glicídios no mel

“…Como já mencionado anteriormente, a ocorrência da reação de trans-D-frutosilação no mel não foi comprovada até o momento. Com relação a melezitose e a 1-cestose, alguns autores consideraram estes trissacarídeos como constituintes da seiva de várias espécies de plantas 86 enquanto, outros 21,87 têm sugerido que esses glicídios seriam carreados para colméia através de coleta das excreções adocicadas de afídeos, as quais estão presentes na superfície das plantas. De fato o mel de melato que é produzido através de excreções de afídeos é rico nesses 2 trissacarídeos enquanto, méis monoflorais têm somente quantidades ínfimas desses compostos 4 .…”

“…De fato o mel de melato que é produzido através de excreções de afídeos é rico nesses 2 trissacarídeos enquanto, méis monoflorais têm somente quantidades ínfimas desses compostos 4 . Outros autores 86 também sugeriram que a presença de erlose poderia ser devida a ação de afídeos, porém, a erlose é encontrada em bem maior quantidade que a melezitose em méis monoflorais. Portanto, a origem da erlose estaria principalmente associada à reação de trans-D-glicosilação no mel.…”