Biomedical subjects

N Bonini

Publications and source records attributed to N Bonini.

4 recordsLinked to original sources

PubMed1997

Expression and function of clift in the development of somatic gonadal precursors within the Drosophila mesoderm.

The gonad forms from cells of two lineages: the germline and soma. The somatic gonadal cells generate the various cell types within the testis or ovary that support gametogenesis. These cells derive from embryonic mesoderm, but how they are specified is unknown. Here, we describe a novel regulator of Drosophila gonadogenesis, clift, mutations in which abolish gonad formation. clift is expressed within somatic gonadal precursors as these cells first form, demonstrating that 9-12 cells are selected as somatic gonadal precursors within each of three posterior parasegments at early stages in gonadogenesis. Despite this early expression, somatic gonadal precursors are specified in the absence of clift function. However, they fail to maintain their fate and, as a consequence, germ cells do not coalesce into a gonad. In addition, using clift as a marker, we show that the anteroposterior and dorsoventral position of the somatic gonadal precursor cells within a parasegment are established by the secreted growth factor Wg, coupled with a gene regulatory hierarchy within the mesoderm. While loss of wg abolishes gonadal precursors, ectopic expression expands the population such that most cells within lateral mesoderm adopt gonadal precursor fates. Initial dorsoventral positioning of somatic gonadal precursors relies on a regulatory cascade that establishes dorsal fates within the mesoderm and is subsequently refined through negative regulation by bagpipe, a gene that specifies nearby visceral mesoderm. Thus, these studies identify essential regulators of gonadal precursor specification and differentiation and reveal novel aspects of the general mechanism whereby distinct fates are allocated within the mesoderm.

Alleles↗

PubMed1991

Small bowel bacterial overgrowth in strongyloidiasis.

Small bowel bacterial growth was studied in patients with strongyloidiasis, and the results were compared to controls. We concluded that in strongyloidiasis there is small bowel bacterial overgrowth, and so it should be considered in the pathogenesis of some of the gastrointestinal manifestations and complications of strongyloidiasis.

Adolescent↗

PubMed1983

Reward learning in normal and mutant Drosophila.

Hungry fruit flies can be trained by exposing them to two chemical odorants, one paired with the opportunity to feed on 1 M sucrose. On later testing, when given a choice between odorants the flies migrate specifically toward the sucrose-paired odor. This appetitively reinforced learning by the flies is similar in strength and character to previously demonstrated negatively reinforced learning, but it differs in several properties. Both memory consolidation and memory decay proceed relatively slowly after training with sucrose reward. Consolidation of learned information into anesthesia-resistant long-term memory requires about 100 min after training with sucrose compared to about 30 min after training with electric shock. Memory in wild-type flies persists for 24 hr after training with sucrose compared to 4-6 hr after training with electric shock. Memory in amnesiac mutants appears to be similarly lengthened, from 1 hr to 6 hr, by substituting sucrose reward for shock punishment. Two other mutants, dunce and rutabaga, which were isolated because they failed to learn the shock-avoidance task, learn normally in response to sucrose reward but forget rapidly afterward. One mutant, turnip, does not learn in either paradigm. Reward and punishment can be combined in olfactory discrimination training by pairing one odor to sucrose and the other to electric shock. In this situation, the expression of learning is approximately the sum of that obtained by using either reinforcement alone. After such training, memory decays at two distinct rates, each characteristic of one type of reinforcement.

Animals↗

PubMedDate not supplied

[D-xilose test during 3 hours. Dose standardization ].

A study is made of the behavior of urinary excretion of D-xilose three and five hours after the ingestion of 5 and 25 g of the substance. Twenty individuals were studied, 13 as control having no intestinal mucosa disease and 7 with steatorrhea and enteric lesions histologically confirmed. An analysis of the results revealed that with both doses it is possible to reduce the test time from five to three hours and thus differentiate the controls from the group of patients. No secondary side effects were observed with 5 g, which were present in 30% (6 cases) of the patients with doses of 25 g. In view of the results the use of 5 g in the test is indicated in the 3 hour test. Under these conditions 95% (1, 645 D.P.) for the controls excreted less than 1, 030 g (21%) of the doses administered.

Adolescent↗