PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “budding”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1993

Morphometric and immunocytochemical assessment of fungiform taste buds after interruption of the chorda-lingual nerve.

Unilateral interruption of the chorda-lingual nerve led to a loss of most epithelial axons and to the deterioration of fungiform taste buds in the anterior portion of the tongue of albino rats, mongolian gerbils, and golden hamsters. By three weeks after surgery the following percentages of fungiform taste buds had completely disappeared: 71% in gerbils, 28% in rats, and 26% in hamsters. Residual taste buds were classified into two groups: atrophic taste buds and taste bud remnants. Atrophic taste buds were smaller than normal and typically had no visible taste pore, although they retained the characteristic oval shape of a taste bud and numerous elongated cells. Taste bud remnants were non-oval fragments of taste buds with few elongated cells. Specific markers for elongated taste cells (monoclonal antibodies to keratin 19) confirmed that atrophic taste buds, as well as some taste bud remnants, had elongated taste cells. By 180 days after chorda-lingual nerve transection, 44% of rat fungiform taste buds had disappeared; morphometric analysis of the 311 residual taste buds established that 241 atrophic taste buds and 69 taste bud remnants were, respectively, 50% and 75% smaller than the average volume of 480 normal taste buds. The aggregate loss of gustatory tissue, calculated from the shrinkage of residual taste buds and the volume lost by the outright disappearance of many taste buds, was 88% for gerbils, 72% for rats, and 65% for hamsters. Evaluation in gerbils of the co-occurrence of taste buds and axons suggests residual taste buds were neurotrophically supported. Every gerbil fungiform papilla that lacked axons lacked a taste bud.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Patterns of bud-site selection in the yeast Saccharomyces cerevisiae.

Cells of the yeast Saccharomyces cerevisiae select bud sites in either of two distinct spatial patterns, known as axial (expressed by a and alpha cells) and bipolar (expressed by a/alpha cells). Fluorescence, time-lapse, and scanning electron microscopy have been used to obtain more precise descriptions of these patterns. From these descriptions, we conclude that in the axial pattern, the new bud forms directly adjacent to the division site in daughter cells and directly adjacent to the immediately preceding division site (bud site) in mother cells, with little influence from earlier sites. Thus, the division site appears to be marked by a spatial signal(s) that specifies the location of the new bud site and is transient in that it only lasts from one budding event to the next. Consistent with this conclusion, starvation and refeeding of axially budding cells results in the formation of new buds at nonaxial sites. In contrast, in bipolar budding cells, both poles are specified persistently as potential bud sites, as shown by the observations that a pole remains competent for budding even after several generations of nonuse and that the poles continue to be used for budding after starvation and refeeding. It appears that the specification of the two poles as potential bud sites occurs before a daughter cell forms its first bud, as a daughter can form this bud near either pole. However, there is a bias towards use of the pole distal to the division site. The strength of this bias varies from strain to strain, is affected by growth conditions, and diminishes in successive cell cycles. The first bud that forms near the distal pole appears to form at the very tip of the cell, whereas the first bud that forms near the pole proximal to the original division site (as marked by the birth scar) is generally somewhat offset from the tip and adjacent to (or overlapping) the birth scar. Subsequent buds can form near either pole and appear almost always to be adjacent either to the birth scar or to a previous bud site. These observations suggest that the distal tip of the cell and each division site carry persistent signals that can direct the selection of a bud site in any subsequent cell cycle.

Cell Division↗
PubMed1997

A role for the actin cytoskeleton of Saccharomyces cerevisiae in bipolar bud-site selection.

Saccharomyces cerevisiae cells select bud sites according to one of two predetermined patterns. MATa and MAT alpha cells bud in an axial pattern, and MATa/alpha cells bud in a bipolar pattern. These budding patterns are thought to depend on the placement of spatial cues at specific sites in the cell cortex. Because cytoskeletal elements play a role in organizing the cytoplasm and establishing distinct plasma membrane domains, they are well suited for positioning bud-site selection cues. Indeed, the septin-containing neck filaments are crucial for establishing the axial budding pattern characteristic of MATa and MAT alpha cells. In this study, we determined the budding patterns of cells carrying mutations in the actin gene or in genes encoding actin-associated proteins: MATa/alpha cells were defective in the bipolar budding pattern, but MATa and MAT alpha cells still exhibit a normal axial budding pattern. We also observed that MATa/alpha actin cytoskeleton mutant daughter cells correctly position their first bud at the distal pole of the cell, but mother cells position their buds randomly. The actin cytoskeleton therefore functions in generation of the bipolar budding pattern and is required specifically for proper selection of bud sites in mother MATa/alpha cells. These observations and the results of double mutant studies support the conclusion that different rules govern bud-site selection in mother and daughter MATa/alpha cells. A defective bipolar budding pattern did not preclude an sla2-6 mutant from undergoing pseudohyphal growth, highlighting the central role of daughter cell bud-site selection cues in the formation of pseudohyphae. Finally, by examining the budding patterns of mad2-1 mitotic checkpoint mutants treated with benomyl to depolymerize their microtubules, we confirmed and extended previous evidence indicating that microtubules do not function in axial or bipolar bud-site selection.

Actins↗
PubMed1990

Postnatal development of palatal and laryngeal taste buds in the hamster.

Mammalian taste buds are distributed within several distinct subpopulations, innervated by branches of three cranial nerves. These taste bud populations originate and mature at different times in various mammalian species and are thought to play differential roles in the control of taste-mediated behaviors. The hamster is a common animal for the electrophysiological study of the gustatory system, and it has been shown that taste buds innervated by the IXth nerve develop postnatally in this species. To delineate further the development of the gustatory system of hamsters, we quantified the number of taste buds appearing on the palatal, nasopharyngeal, and laryngeal epithelium from birth through 120 days of age. Taste buds are present in almost adult numbers on the soft palate at birth, but only 39% of these are mature. Distinct taste pores, indicative of mature taste buds, increase in number until about 20-30 days of life, at which time all of the taste buds on the soft palate and on the nasoincisive papillae are fully developed. Taste buds are concentrated primarily on the posterior and medial portions of the soft palate. Taste buds located on the laryngeal surface of the epiglottis and the aryepiglottal folds are absent at birth and originate and mature over the following 120 days. Laryngeal taste buds are more concentrated on the aryepiglottal folds than on the epiglottis. On the soft palate and in the epiglottal region, the maturation of taste buds is well characterized by a logarithmic function (Y = a log X + B) relating the number of mature taste buds to postnatal age. On the soft palate, the length of the taste buds from base to apex correlates with the thickness of the epithelium, which increases with development. The diameter of mature taste buds on the soft palate does not change with age. In contrast to many mammalian species, in rodents taste bud development occurs mostly after birth. Rapid postnatal development progresses at a time when ingestive behavior is undergoing a number of significant changes. Taste buds in the larynx have been implicated in a number of laryngeal reflexes (i.e., apnea, swallowing) in several nonrodent species. The electrophysiological properties of superior laryngeal nerve fibers would suggest a similar function for epiglottal taste buds in the hamster.

Animals↗
PubMed1991

The rate and locus of development of rat vallate taste buds.

Several hundred taste buds develop and mature in the trench walls of the rat's vallate papilla during the first 3 months after birth. The objective of this investigation of taste bud development was to determine: (i) whether the vallate papilla has local growth zones where new taste buds form, (ii) whether new taste buds arise by the division of mature taste buds, (iii) how many days are required for a new taste bud to mature, and (iv) whether a taste pore forms as the taste bud reaches a critical volume. Camera lucida drawings were made of more than 4000 iron hematoxylin-stained, serially sectioned, vallate taste buds. The relative abundance of immature taste buds declined exponentially with age, from 18% of the mature taste buds at day 15 to 2% at day 90. At days 21, 33 and 45 most of the immature taste buds (those lacking a taste pore) were located in growth zones at the anterior and posterior extremes of the vallate trench. A mean of 10.5 days was required for the maturation of each cohort of immature taste buds present at days 15, 21, 33 and 45. Vallate taste buds were added de novo; fission of mature taste buds was rare. Taste buds varied widely in the taste bud volume at which a pore formed and in the final volume of the taste bud.

Animals↗