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PubMed1998

The innervation of taste buds in the soft palate and circumvallate papilla of the rat as revealed by the zinc iodide-osmium tetroxide technique.

The taste buds in the soft palate and the circumvallate papillae of the rat were investigated by the zinc iodide-osmium tetroxide technique. In addition, electron micrographs of taste buds stained with this method were presented for the first time. Differences in taste bud structures were found between the examined regions. The taste buds of the soft palate showed a complicated plexus of intragemmal nerve fibers. Some fibers exhibited terminal polymorphic swellings. Single branches could be traced close to the space of the taste pore. In the soft palate, the taste bud cells remained unstained, whereas in the circumvallate papillae of the tongue, a subpopulation of taste bud cells could be selectively stained and the intragemmal nerve fibers were characterized by large varicosities. The morphological dissimilarities between the taste buds of the investigated regions might be explained by their functional characteristics, or possibly their varying affinities to the taste qualities. Electron microscopic investigation of the stained circumvallate papillae revealed that the electron-dense reaction product had primarily accumulated in a subpopulation of light cells. Dark cells exhibited only a slight labelling. In detail, the precipitate was found loosely distributed in the cytoplasm as well as the nuclei of the cells, and particularly concentrated at the membranes of light vacuoles, this probably being profiles of dilated endoplasmic reticulum. A few roundish accumulations of precipitate were seen in the cytoplasm of taste bud cells, which showed no intensive light microscopic staining. Labelled material was also found within the taste pores outside the apical processes of the cells. The present findings indicate that the zinc iodide-osmium tetroxide technique is applicable to neuroanatomical studies of taste buds.

Animals↗

PubMed2004

[Experimental study of the fungiform papilla and taste bud regeneration following microsurgical repair of lingual nerve in rat].

PURPOSE: To investigate the changes of taste buds following injury to lingual nerve and the regeneration of the fungiform papillae and taste buds following microsurgical epineurial anastomosis of transecting injured lingual nerves in rats. METHODS: We observed the numbers and shapes of the fungiform papillae and taste buds with stereomicroscope, light microscope, and scanning electron microscope at 20 and 100 days after the clamp injury to lingual nerve, or the transecting injury to lingual nerve with/without immediate microsurgical epineurial anastomosis of the injured lingual nerve in rats. RESULTS: The fungiform papillae and taste buds degenerated, atrophied and their numbers diminished obviously at 20 days following either the clamp injury or transecting injury to the lingual nerve. The fungiform papillae and taste buds didn't regenerate spontaneously at 100 days following transection of the lingual nerve without microsurgery. The degenerated fungiform papillae and taste buds regenerated and recovered completely at 100 days following both clamp injury to the lingual nerve and transection of the lingual nerve with immediate microsurgical epineurial anastomosis. CONCLUSION: The degenerated fungiform papillae and taste buds have good ability to regenerate spontaneously following clamp injury to the lingual nerve; the degenerated fungiform papillae and taste buds can regenerate completely with immediate microsurgical epineurial anastomosis of the transected lingual nerve. The quantity and morphology of fungiform papillae and taste buds can be used as objective indicators in the function rehabilitation of injured lingual nerve.

Animals↗

PubMed1980

Further observations on the occurrence of taste buds in the papilla palatina of primates.

1. Taste buds occur in the epithelium of the papilla of Galago crassicaudatus and demidovi, Perodicticus potto and Microcebus murinus. The taste buds are found single or in groups of 2 or 3. A taste area ocurs in Galago crassicaudatus and Perodicticus potto. 2. The pattern of the distribution of the taste buds in the species studied is basically the same as found previously in Nycticebus and Tupaia. The taste buds are found in the oral part of the papilla palatina exclusively, far oral to the orifices of the ductus nasopalatinus and vomeronasalis. 3. From the orientation of the taste buds it can be concluded that they taste substances entering the sulcus papillae palatinae, because the buds point at the entrances and at the lumen of that sulcus. Since substances may approach the anterior part of the papilla from the oral direction the taste buds in this area point rostrally. In Galago the anteriormost taste buds are situated in the median plane pointing at the slit between the epithelial laminae of the labial folds. 4. Many taste buds were found in the process of disintegration.

Animals↗

PubMed2001

Possible contribution of CD44 variant 6 and nuclear beta-catenin expression to the formation of budding tumor cells in patients with T1 colorectal carcinoma.

BACKGROUND: In an earlier study, the authors demonstrated that tumor budding was useful for predicting lymph node metastasis in patients with early invasive (T1) colorectal carcinoma. This study was undertaken to clarify the associations between tumor budding, E-cadherin-catenin complex, and CD44 variant 6 abnormalities. METHODS: In 51 T1 colorectal carcinomas, tumor budding (the number of dedifferentiation units at the invasive margin) on hematoxylin and eosin-stained slides was counted under light microscopy. Immunostaining for E-cadherin, alpha-catenin, beta-catenin, and CD44 variant 6 was performed on formalin fixed, paraffin embedded sections. The associations between locoregional failure (lymph node metastasis or local recurrence) and tumor budding and clinicopathologic parameters and immunoreactivity were examined statistically. RESULTS: In univariate analysis, tumor budding and nuclear beta-catenin expression were associated significantly with locoregional failure (P = 0.004, 0.01). Multivariate analysis showed that tumor budding alone was associated significantly with locoregional failure (P = 0.02), and the association between nuclear beta-catenin expression and locoregional failure was marginally significant (P = 0.07). Analysis of variance showed that lymphatic invasion alone was associated significantly with tumor budding (P = 0.02), and there was a significant interaction effect for tumor budding between CD44 variant 6 expression and nuclear beta-catenin expression (P = 0.01). There was a significant correlation between expression patterns of these two molecules and locoregional failure (P = 0.01). CONCLUSIONS: The current results suggest that the up-regulation of CD44 variant 6 through nuclear beta-catenin activation may contribute to the formation of tumor budding, and immunostaining of these two adhesion molecules may be useful in identifying those at high-risk for locoregional failure among patients with T1 colorectal carcinoma.

Adult↗

PubMed1984

Cellular composition and organization of ductal buds in developing rat mammary glands: evidence for morphological intermediates between epithelial and myoepithelial cells.

In the developing rat mammary gland, terminal end buds (TEBs), lateral buds and alveolar buds represent the major sites of morphogenetic activity and cellular differentiation. The morphology and cellular composition of these buds from 20-to 22-day-old rats and cycling rats have been studied by immunocytochemical and electron microscopic techniques. The mammary buds are composed of a heterogeneous collection of cells including epithelial and myoepithelial cells, irregular loosely adherent cells, and occasional large clear cells. The irregular, loosely packed cells or cap cells are mainly situated around the periphery of the TEBs and lateral buds. "Chains" of irregularly shaped cells also extend from the peripheral cap cell layer to the center of the TEB; and, where they converge on lumina, they display microvilli and junctional complexes. At the tips of the end buds, the cap cells are of undifferentiated appearance; however, similar cells situated toward the subtending mammary ducts show a gradation in ultrastructure to that of myoepithelial cells. This change is accompanied by an increase in the amounts of immunoreactive myosin and keratin seen within the cells and a 200-fold increase in the thickness of the basement membrane. In contrast, the peripheral cells of the alveolar buds are more closely packed, contain a greater number of myofilaments, and show increased staining with antisera to myosin. We suggest that the undifferentiated cap cells do not represent a discrete cell type, since they show transitional forms to myoepithelial cells within the subtending mammary ducts, and that the tendency toward the myoepithelial phenotype is predominant in the more differentiated structures, the alveolar buds.

Animals↗

PubMed1988

A test of positional properties of avian wing-bud mesoderm.

Supernumerary wing structures are readily produced by grafting pieces of wing-bud mesoderm into different locations of host wing buds, but the mechanism underlying their formation remains obscure. The major aim of this study was to examine the ability of posterior quail wing-bud mesoderm, cultured in vitro long enough to lose ZPA (zone of polarizing activity) activity, to stimulate or participate in the formation of supernumerary structures when grafted into anterior slits of host chick wing buds. Small pieces of anterior and posterior quail wing-bud mesoderm (HH stages 21-23) were placed in in vitro culture for up to 3 days. After 2 days, ZPA activity of cultured mesoderm was lost. After the grafting of 2- to 3-day cultured anterior quail wing-bud mesoderm into posterior slits of host chick wing-buds, a consistently high percentage (70%-90%) of grafts result in formation of supernumerary cartilage; in this experiment, however, only a low percentage of grafts resulted in supernumerary cartilage when 2- to 3-day cultured posterior mesoderm was grafted into anterior slits. Taken with controls, these results show that positional differences exist between cultured anterior and posterior wing-bud mesoderm. Serial-section analysis of numerous operated wings has shown several patterns of contribution to supernumerary structures by cells of graft and host. Single supernumerary digits induced by grafts of ZPA mesoderm into anterior slits were normally composed entirely of host cells, but graft cells regularly contributed to skeletal elements of more complex supernumerary structures. Cartilage rods produced by anterior-to-posterior grafts were composed mostly of graft cells, but cartilage nodules and the bases of some rods were often mosaics of chick and quail cells. The results support the proposition that mesodermal cells of the quail wing-bud possess a form of anteroposterior positional memory, but its nature and the means by which the memory of grafted cells interacts with host mesoderm are still not clear.

Animals↗

PubMed1993

Selective expression of the chicken platelet-derived growth factor alpha (PDGF alpha) receptor during limb bud development.

Platelet-derived growth factor (PDGF) affects proliferation and differentiation of chicken limb bud mesoderm in vitro. However, no PDGF receptor has been characterized in the chicken wing bud in vivo. In this study, we used reverse transcription PCR (rtPCR), Northern blot analysis, and Western blot analysis to identify a molecule, in the developing wing bud, which represents the chicken homolog of the PDGF alpha receptor. The chicken PDGF alpha receptor mRNA was present in both mesoderm and ectoderm and all stages of the developing limb bud examined. Cultured limb bud mesoderm also expressed the PDGF alpha receptor transcript. In addition, the PDGF alpha receptor protein was present in whole limb buds and cultured limb bud mesoderm. Expression of the PDGF alpha receptor in cultured mesoderm was independent of the presence of ectoderm cells. The relative sizes of both the mRNA and protein for the PDGF alpha receptor in the chicken limb bud were similar to mammalian counterparts. Using similar approaches, neither the mRNA nor protein representing the chicken homolog of the PDGF beta receptor was detected. These data demonstrate for the first time that a PDGF alpha receptor is present in the embryonic chicken limb bud and may help regulate growth and differentiation of the embryonic limb.

Amino Acid Sequence↗

PubMed1995

Expression of genes encoding bone morphogenetic proteins and sonic hedgehog in talpid (ta3) limb buds: their relationships in the signalling cascade involved in limb patterning.

The chicken mutant talpid3 (ta3) has polydactylous limbs with up to 7-8 morphologically similar digits. This lack of antero-posterior polarity in digit pattern is correlated with symmetrical expression of genes of the HoxD complex. We determined the distribution of polarizing activity in limb buds of the chick mutant ta3 by assessing the ability of mesenchyme from various positions along the antero-posterior axis to induce digit duplications when grafted anteriorly into a normal limb. Cells with highest polarizing activity were found at the posterior margin of the wing as in the polarizing region of normal limb buds. However, in contrast to normal limb buds, ta3 anterior mesenchyme also had low polarizing activity. Application of retinoic acid or a polarizing region graft to the anterior of ta3 limb buds changed digit morphology but did not induce digit duplications or digits with any characteristic a-p pattern. To determine which genes are associated with polarizing activity and which are associated with patterning of the digits, we examined expression of the genes Sonic hedgehog (shh), Bmp-2, and Bmp-7, whose expression is normally confined to the posterior margin of the early wing bud and is associated with the polarizing region. In addition, we determined the distribution of Fgf-4 transcripts which in normal limb buds are restricted to the posterior part of the apical ectodermal ridge. In ta3 limb buds, shh expression is restricted to the posterior limb mesenchyme, which has high polarizing activity, but is not expressed in regions which have low polarizing activity. In contrast, Bmp-2 and Bmp-7 are expressed uniformly along the a-p axis. Fgf-4 transcripts are present throughout the apical ectodermal ridge in ta3 limb buds. In the ta3 mutant, there is both an abnormal distribution of signalling activity and response to polarizing signals. In addition, the dissociation between the expression of shh and Bmps suggests distinct roles for the encoded molecules in signalling and response in a-p patterning of limb buds.

Animals↗

PubMed1976

Budding by oozooids in the polystyelid ascidian Metandrocarpa tayori Huntsman.

Larvae of the stolidobranch ascidian Metandrocarpa taylori molt a thin sheath upon settling, then metamorphose and radiate a larval complement of vascular ampullae upon the substrate. These ampullae thereafter regress, "rest" in a reduced condition for several weeks, and then regrow into the oozooid's definitive array of vascular ampullae in accompaniment to the development of the oozooidal vascular nest of test-vessels. Pallial buds emerge some four months after the larva settles; the oozooid has by then grown to a length of at least 2 mm and its vascular nest is surrounded by at least 16 vascular ampullae. Oozooids bud one to five buds (mean, 2.6) in a rather short period of blastogenic vigor, then persist in the colony. Late buds are frequently aborted. Buds appear anywhere around the basal margin of the oozooid, but more often on the left than the right and more often posteriorly than anteriorly. As other studies have observed with blastozooids, this study notes an integration of budding and the disposition of the elements of the test-vessel system of oozooids. Buds emerge oriented tangentially to the parental basal margin at the bud-site, then often rotate to point their anterior ends away from the parent. No larvae metamorphosed into oozooids with situs inversus viscerum, but in this study two oozooids extruded blastozooids showing this anomaly; these blastozooids budded "reversed" zooids in turn, so that entire clonal lines showed the anomaly.

Animals↗

PubMed2001

Three amphioxus Wnt genes (AmphiWnt3, AmphiWnt5, and AmphiWnt6) associated with the tail bud: the evolution of somitogenesis in chordates.

The amphioxus tail bud is similar to the amphibian tail bud in having an epithelial organization without a mesenchymal component. We characterize three amphioxus Wnt genes (AmphiWnt3, AmphiWnt5, and AmphiWnt6) and show that their early expression around the blastopore can subsequently be traced into the tail bud; in vertebrate embryos, there is a similar progression of expression domains for Wnt3, Wnt5, and Wnt6 genes from the blastopore lip (or its equivalent) to the tail bud. In amphioxus, AmphiWnt3, AmphiWnt5, and AmphiWnt6 are each expressed in a specific subregion of the tail bud, tentatively suggesting that a combinatorial code of developmental gene expression may help generate specific tissues during posterior elongation and somitogenesis. In spite of similarities within their tail buds, vertebrate and amphioxus embryos differ markedly in the relation between the tail bud and the nascent somites: vertebrates have a relatively extensive zone of unsegmented mesenchyme (i.e., presomitic mesoderm) intervening between the tail bud and the forming somites, whereas the amphioxus tail bud gives rise to new somites directly. It is likely that presomitic mesoderm is a vertebrate innovation made possible by developmental interconversions between epithelium and mesenchyme that first became prominent at the dawn of vertebrate evolution.

Animals↗

PubMed2007

Tumor budding as a prognostic marker in stage-III rectal carcinoma.

BACKGROUND AND AIM: Tumor budding along the invasive margin is known to be associated with biological behavior in colorectal carcinoma. The aims of this study were to explore if the semiquantitative assessment of tumor budding in rectal cancers correlates with oncological behavior and to appraise if the tumor budding is valid as a pathological parameter in distinguishing tumors with higher malignancy potential from those with lower one for prognostic stratification. MATERIALS AND METHODS: Surgical specimens from 244 patients with well- or moderately differentiated rectal carcinoma were retrieved to assess the intensity of tumor budding at the invasive margin. Intensities were divided semiquantitatively into four groups based on quartiles, and the 5-year disease-free survivals (DFS) were analyzed to search for a cutoff point of prognostic stratification. RESULTS: The cutoff of the intensity considered to be the best indicator for dividing patients into subgroups with different DFS was between quartiles 3 and 4, but this survival difference in subgroups in either side of the cutoff was significant only in stage-III disease [5-year DFS, 62.1 vs 35.1%; p = 0.0023; 95% confidence interval (CI), 0.1824-0.6919]. Based on multivariate analysis, the intensity of budding proved to be an independent variable associated with DFS (hazard ratio, 2.005; p = 0.0086; 95% CI, 1.021-3.934). When scores were given to grade of budding (lower, 0; higher, 1) and N stage (N1, 0; N2, 1) in stage III, a better prognostic stratification in terms of the 5-year DFS was obtained than the American Joint Committee on Cancer nodal staging only (0 vs 1 vs 2, 66.5 vs 42.6 vs 29.2%; p = 0.0101). CONCLUSIONS: Quantitative assessment of tumor budding is a reliable biological prognostic variable to identify higher malignancy potential. Scoring system using tumor budding and N stage showed better prognostic stratification in stage-III rectal carcinoma. A prospective evaluation would confirm the clinical significance of tumor budding for prognostic stratification.

Adult↗

PubMed2003

Control of head morphogenesis in an invertebrate asexually produced larva-like bud ( Cassiopea andromeda; Cnidaria: Scyphozoa).

Scyphopolyps of Cassiopea andromeda propagate asexually by forming larva-like buds which separate from the parent in a developmentally quiescent state. These buds metamorphose into sessile polyps when exposed to specific biogenic, chemical inducers. Morphogenesis of transversely dissected buds indicates the presence of pattern-determining signals; whereas the basal bud fragments may still form a complete scyphistoma the apical bud fragments develop spontaneously in the absence of an inducer into a polyp head without stalk and foot. Based on these findings Neumann (dissertation, Cologne University, 1980) postulated a head-inhibiting signal which is released at the basal pole and inhibits head formation at the apical end. Contrary to this hypothesis dissection itself might induce the development of head structures. The present study deals with the control of polyp head formation in C. andromeda. It concentrates on two points, namely the postulated head inhibitor and the involvement of compounds known to act during metamorphosis (the enzyme protein kinase C and the specific metamorphosis inducer Z-GPGGPA). We found that compared to intact buds and apical bud fragments transversely incised buds reached an intermediate stage of head development. This confirms Neumann's hypothesis. Consequently we focused on the mode of action and the chemical nature of the head-inhibiting signal in C. andromeda. Our results indicate that the head inhibitor may be included in one of six pooled fractions isolated from bud homogenate via gel filtration on a Sephadex G-50 column. The inhibitor is supposed to be water-soluble and to have a molecular weight of 850-1,500 Da. Furthermore we prove that head formation is not promoted by the metamorphosis-inducer Z-GPGGPA but is prevented by the inhibitors psychosine, chelerythrine and RO-32-0432 showing the involvement of protein kinase C in this process.

Alkaloids↗

PubMed2005

Seasonal changes in foliar terpenes indicate suitability of Douglas-fir buds for western spruce budworm.

The terpene composition of current-year buds of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, was analyzed from before budburst to after buds were fully flushed. Terpene composition was measured at weekly intervals for several seasons at eight different locations in the southern interior of British Columbia, Canada. Discriminant functions relating terpene composition to suitability of buds for newly emerged western spruce budworm, Choristoneura occidentalis Freeman, were developed based on terpene profiles of the buds and bioassays measuring the suitability to budworms of a sister group of buds. Changes in percent composition of bud terpenes before and during budburst were closely associated with changes in the suitability of the buds to utilization by budworms at both the tree and site by date levels. Use of a degree-day scale for bud suitability removed much of the year-to-year variation, but remaining differences among sites suggest additional sources of variation influencing the insect host plant relationship. The success of correctly classifying bud suitability using terpene profiles demonstrates the value of foliar terpenes as indicators of seasonal changes in suitability of Douglas-fir foliage during the critical spring emergence period of western spruce budworm. This indicator could be used to screen individual trees susceptible to budworm damage and identify sites at high risk of damaging defoliation.

Animals↗

PubMed1983

Cold hardiness in various organs and tissues of Rhododendron species and the supercooling ability of flower buds as the most susceptible organ.

The freezing resistance of various organs and tissues was determined in 24 Rhododendron species (mainly Subgenus Tsutsutsi) having different ecological distributions. The order of hardiness for organ or tissue is as follows: leaf bud greater than wood greater than or equal to bark greater than flower bud, and the flower bud is characterized as the most cold-susceptible organ. The relationship of killing temperature (KT) to northern distribution was the most significant in leaf buds compared to other organs and tissues. KTs of leaf buds for the most hardy species were -45 degrees C (or below) and those for the most tender species were about -23 degrees C, while KTs of flower buds were about -28 degrees C for the former and -16 degrees C for the latter. Although KTs of flower buds native to southwestern Japan were well correlated with the exothermic temperature distribution (ETD) of florets, those in the more northern species were generally lower than ETDs. The supercooling ability of flower buds appears to be sufficient to avoid the freezing stress since the extreme minimum temperature (EMT) at the northern limit of natural distribution for each tree species examined was not lower than the KT and ETD of the flower buds.

Freezing↗

PubMed1995

Organization and development of the tail bud analyzed with the quail-chick chimaera system.

After closure of the posterior neuropore, the caudal part of the embryo designated as the 'tail bud' forms a mass of undifferentiated cells from which the lumbosacral and caudal parts of the body develop. It has been proposed that the tail bud is a homogeneous structure comparable to a blastema (Holmdahl, 1925; Griffith et al., 1992). Another view is that morphogenesis of the tail bud is merely the continuation of the gastrulation process (Pasteels, 1937, 1943). In order to try to solve this controversy, we have studied the fate of definite and discrete regions of the tail bud at the 25-somite stage by using the quail-chick marker system. We found that the tail bud is composed of different domains endowed with a definite fate. A ventro-rostral region equivalent to the chordo-neural hinge defined by Pasteels gives rise to the notochord and floor plate and thus corresponds to the Hensen's node which in the tail bud pursues its rostrocaudal movement. The presumptive territory of the lateral walls of the lumbo-sacro-caudal neural tube is located caudally to the Hensen's node as it stands at the 25-somite stage. Material destined to form the sacral and caudal somites is still located in the dorsal midline in the caudalmost part of the tail bud. We thus show that the movements of invagination and divergence which characterize gastrulation are still going on in the tail bud after the 25-somite stage. Thus the somitic material located medio-dorsally diverges laterally and contributes by apposition to the growth of the trunco-caudal part of the body. The parallel between tail bud development in Amniotes and Amphibians as described recently by Gont et al. (1993) is striking and points to the unity in the development mechanisms within the Vertebrate phylum.

Animals↗

PubMed2000

The role of the proteins Kar9 and Myo2 in orienting the mitotic spindle of budding yeast.

BACKGROUND: Two genetic 'pathways' contribute to the fidelity of nuclear segregation during the process of budding in the yeast Saccharomyces cerevisiae. An early pathway, involving Kar9p and other proteins, orients the mitotic spindle along the mother-bud axis. Upon the onset of anaphase, cytoplasmic dynein provides the motive force for nuclear movement into the bud. Loss of either pathway results in nuclear-migration defects; loss of both is lethal. Here, to visualize the functional steps leading to correct spindle orientation along the mother-bud axis, we imaged live yeast cells expressing Kar9p and dynein as green fluorescent protein fusions. RESULTS: Transport of Kar9p into the bud was found to require the myosin Myo2p. Kar9p interacted with microtubules through the microtubule-binding protein Bim1p and facilitated microtubule penetration into the bud. Once microtubules entered the bud, Kar9p provided a platform for microtubule capture at the bud cortex. Kar9p was also observed at sites of microtubule shortening in the bud, suggesting that Kar9p couples microtubule shortening to nuclear migration. CONCLUSIONS: Thus, Kar9p provides a key link between the actin cytoskeleton and microtubules early in the cell cycle. A cooperative mechanism between Kar9p and Myo2p facilitates the pre-anaphase orientation of the spindle. Later, Kar9p couples microtubule disassembly with nuclear migration.

Actins↗

PubMed2002

Volatile production by buds and corollas of two sympatric, confamilial plants, Ipomopsis aggregata and Polemonium foliosissimum.

We used solid-phase microextraction of headspace samples followed by gas chromatography and mass spectrometry to identify and quantify the major volatile compounds produced by the buds and corollas of Ipomopsis aggregata (Polemoniaceae), and we compared them to a sympatric, confamilial plant species, Polemonium foliosissimum. The two species have distinct floral morphologies and pollinators, but share a common predispersal seed predator that oviposits under the calyces of buds. Ipomopsis aggregata buds emitted fewer compounds than the corollas. The buds of I. aggregata were dominated by alpha-pinene and, to a lesser extent, beta-pinene. The corollas of I. aggregata emitted a mixture of 10 compounds. Like the buds, I. aggregata corollas produced relatively high concentrations of alpha-pinene as well as caryophyllene. In addition, the emission of four terpenoids, three esters, and one ketone added to the volatile bouquet of the corollas. Polemonium foliosissimum buds also emitted fewer compounds than the corollas. The buds of P. foliosissimum were dominated by beta-pinene and, to a lesser extent, alpha-pinene. The corollas of P. foliosissimum were also dominated by beta-pinene along with three terpenoids, three alcohols, one ester, and two aldehydes. Comparing I. aggregata and P. foliosissimum, bud samples from both species produced considerable amounts of alpha- and beta-pinene. Ipomopsis aggregata emitted more alpha-pinene than beta-pinene, while P. foliosissimum emitted more beta-pinene. The corollas of the two species, however, differed in their volatile bouquet. The partition of volatiles between I. aggregata and P. foliosissimum buds and corollas and differences in volatile production between I. aggregata and P. foliosissimum are consistent with selection pressures exerted by organisms interacting with these plants.

Adaptation, Physiological↗

PubMed2003

The upstream regulator, Rsr1p, and downstream effectors, Gic1p and Gic2p, of the Cdc42p small GTPase coordinately regulate initiation of budding in Saccharomyces cerevisiae.

BACKGROUND: Cdc42p, a Rho family small GTPase, is essential for budding initiation in the yeast Saccharomyces cerevisiae. The homologous proteins Gic1p and Gic2p (Gic1/2p) are effectors of Cdc42p, but their precise functions remain unknown. Rsr1p/Bud1p is a Ras family small GTPase that controls the selection of the budding site. Previous observations suggested that Rsr1p-GTP recruits Cdc24p, a GDP/GTP exchange factor for Cdc42p, at the incipient bud site. However, this model only addresses how Rsr1p determines the budding site, because the rsr1 mutant normally initiates budding. RESULTS: Here we show that a rsr1 gic1 gic2 mutant fails to initiate budding, resulting in unbudded, large, and multinucleated cells. Expression of a dominant active or dominant negative mutant of RSR1 also inhibited the growth of the gic1 gic2 mutant, suggesting that cycling of Rsr1p between the GTP- and GDP-bound forms is required for budding initiation in the gic1 gic2 mutant. Among the mutations in effectors of CDC42, only the gic1 gic2 mutation demonstrated a synthetic lethal interaction with rsr1. Increased gene dosage of CDC42 suppressed defects in budding initiation of rsr1 gic1 gic2 mutants containing additional mutations in other effectors of CDC42, including BNI1, CLA4 or STE20. The polarized localization of Bni1p-GFP (green fluorescent protein) and Cla4p-GFP was lost after depletion of Gic1p in the rsr1 gic2 mutant. CONCLUSION: We propose that Gic1/2p may stabilize or maintain a complex consisting of Cdc42p-GTP and its effectors at the budding site, which are assembled by the action of the Rsr1p-Cdc24p system.

Adaptor Proteins, Signal Transducing↗