[Effect of Neodymium-Doped Yttrium Aluminum Garnet Laser Combined With Desensitizing Toothpaste on Dentinal Tubule Occlusion Against Acid Challenge].

Objective To assess the effects of different application sequences of neodymium-doped yttrium aluminum garnet(Nd∶YAG)laser and the desensitizing toothpaste containing stannous fluoride on dentinal tubule occlusion.Methods Twelve intact third molars freshly extracted from human were selected and prepared into dentin slices with a thickness of 0.8 mm.Each dentin slice was subdivided into four small slices,three of which were etched with 6% citric acid and randomly assigned to the following three groups(n=12):(1)control group:no treatment;(2)Nd∶YAG+toothbrushing(TB)group:first irradiated with Nd∶YAG laser and then brushed with desensitizing toothpaste;(3)TB+Nd∶YAG group:first brushed with desensitizing toothpaste and then irradiated with Nd∶YAG laser.The Nd∶YAG laser irradiation were carried out at 1 W,15 pulses/s,and the pulse width of 150 µs for 10 s(for a total of 6 cycles).After the above treatment,the 12 dentin slices from the Nd∶YAG+TB and TB+Nd∶YAG groups were randomly assigned to four subgroups(n=3)and subjected to acid etching in the Coca-Cola solution for 0,5,10,and 15 min.A scanning electron microscope was used to observe and photograph the dentin slices in each group,and eight single-blinded examiners scored the slices according to uniform criteria.The analysis of variance was carried out to compared the scores between groups.Results Before acid etching,the dentin tubule occlusion scores of the Nd∶YAG+TB and TB+Nd∶YAG groups were(4.83±0.09) scores and(3.85±0.66) scores,respectively,which had no significant difference between each other(P=0.0590)and were higher than that[(0.10±0.07)scores]of the control group(both P<0.0001).The dentin tubule occlusion scores of the Nd∶YAG+TB group after acid etching for 5,10,and 15 min were(4.33±0.60)scores,(4.27±0.24)scores,and(3.63±0.07)scores,respectively,which were not significantly different from those[(4.04±0.10)scores,(3.76±0.59)scores,and(3.17±0.29)scores,respectively]of the TB+Nd∶YAG group(all P>0.05).In the Nd∶YAG+TB subgroup,the dentin tubule occlusion score after acid etching for 15 min was significantly lower than that before acid etching(P=0.0011).In the TB+Nd∶YAG group,there was no statistically significant difference in the score between before and after acid etching(P>0.05).Conclusions Nd∶YAG laser irradiation with appropriate parameters combined with the use of desensitizing toothpaste could produce an excellent occluding effect on dentinal tubules regardless of the sequence.However,brushing with desensitizing toothpaste followed by Nd∶YAG laser irradiation produced more consistent dentin sealing after acid etching.

Autolysosomal exocytosis of lipids protect neurons from ferroptosis.

During oxidative stress neurons release lipids that are internalized by glia. Defects in this coordinated process play an important role in several neurodegenerative diseases. Yet, the mechanisms of lipid release and its consequences on neuronal health are unclear. Here, we demonstrate that lipid-protein particle release by autolysosome exocytosis protects neurons from ferroptosis, a form of cell death driven by lipid peroxidation. We show that during oxidative stress, peroxidated lipids and iron are released from neurons by autolysosomal exocytosis which requires the exocytic machinery VAMP7 and syntaxin 4. We observe membrane-bound lipid-protein particles by TEM and demonstrate that these particles are released from neurons using cryoEM. Failure to release these lipid-protein particles causes lipid hydroperoxide and iron accumulation and sensitizes neurons to ferroptosis. Our results reveal how neurons protect themselves from peroxidated lipids. Given the number of brain pathologies that involve ferroptosis, defects in this pathway likely play a key role in the pathophysiology of neurodegenerative disease.

Neuronal ROS-induced glial lipid droplet formation is altered by loss of Alzheimer's disease-associated genes.

A growing list of Alzheimer's disease (AD) genetic risk factors is being identified, but the contribution of each variant to disease mechanism remains largely unknown. We have previously shown that elevated levels of reactive oxygen species (ROS) induces lipid synthesis in neurons leading to the sequestration of peroxidated lipids in glial lipid droplets (LD), delaying neurotoxicity. This neuron-to-glia lipid transport is APOD/E-dependent. To identify proteins that modulate these neuroprotective effects, we tested the role of AD risk genes in ROS-induced LD formation and demonstrate that several genes impact neuroprotective LD formation, including homologs of human ABCA1, ABCA7, VLDLR, VPS26, VPS35, AP2A, PICALM, and CD2AP Our data also show that ROS enhances Aß42 phenotypes in flies and mice. Finally, a peptide agonist of ABCA1 restores glial LD formation in a humanized APOE4 fly model, highlighting a potentially therapeutic avenue to prevent ROS-induced neurotoxicity. This study places many AD genetic risk factors in a ROS-induced neuron-to-glia lipid transfer pathway with a critical role in protecting against neurotoxicity.

Pex20p functions as the receptor for non-PTS1/non-PTS2 acyl-CoA oxidase import into peroxisomes of the yeast Yarrowia lipolytica.

Most soluble proteins targeted to the peroxisomal matrix contain a C-terminal peroxisome targeting signal type 1 (PTS1) or an N-terminal PTS2 that is recognized by the receptors Pex5p and Pex7p, respectively. These receptors cycle between the cytosol and peroxisome and back again for multiple rounds of cargo delivery to the peroxisome. A small number of peroxisomal matrix proteins, including all six isozymes of peroxisomal fatty acyl-CoA oxidase (Aox) of the yeast Yarrowia lipolytica, contain neither a PTS1 nor a PTS2. Pex20p has been shown to function as a co-receptor for Pex7p in the import of PTS2 cargo into peroxisomes. Here we show that cells of Y. lipolytica deleted for the PEX20 gene fail to import not only the PTS2-containing protein 3-ketoacyl-CoA thiolase (Pot1p) but also the non-PTS1/non-PTS2 Aox isozymes. Pex20p binds directly to Aox isozymes Aox3p and Aox5p, which requires the C-terminal Wxxx(F/Y) motif of Pex20p. A W411G mutation in the C-terminal Wxxx(F/Y) motif causes Aox isozymes to be mislocalized to the cytosol. Pex20p interacts physically with members of the peroxisomal import docking complex, Pex13p and Pex14p. Our results are consistent with a role for Pex20p as the receptor for import of the non-PTS1/non-PTS2 Aox isozymes into peroxisomes.

Gingivitis Models - Relevant Approaches to Assess Oral Hygiene Products.

OBJECTIVES: To review the application of gingivitis prevention and treatment models to assess the efficacy of mechanical and chemotherapeutic oral hygiene interventions following shorter- and longer-term use. METHODS: Representative published clinical trials evaluating the shorter- and longer-term anti-gingivitis efficacy of stannous fluoride dentifrice, cetylpyridinium chloride (CPC) rinse, and oscillating-rotating (O-R) electric rechargeable toothbrushes were reviewed. Key gingivitis indices, including the Löe-Silness Gingival Index (LS), Lobene Modified Gingival Index (MGI), Gingival Bleeding Index (GBI), Papillary Bleeding Index (PIBI), and the Mazza modification of the PIBI (Mazza GI), were evaluated for their relative validity and sensitivity in evaluating prevention and treatment outcomes. RESULTS: Twenty clinical trials were evaluated, including 11 treatment studies and 9 prevention trials. Collectively, the findings demonstrated the efficacy of stabilized stannous fluoride toothpaste, CPC rinses, and O-R electric toothbrushes in improving gingival health both in longer-term prevention and shorter-term treatment models. The studies employed various frequently used gingivitis indices. The indices were sufficiently sensitive to elucidate treatment differences. CONCLUSIONS: Based on the results of this review, gingivitis prevention and treatment studies are valid approaches to show treatment effects, and their utilization is dependent upon whether the intention is to evaluate "reducing the onset of gingivitis" or "reducing the severity of existing gingivitis." Various indices, including the LS, MGI, GBI, PIBI, and Mazza GI indices, provide valid measurements for evaluating gingivitis in treatment and prevention models. Shorter-term treatment models allow for efficient efficacy evaluation in clinically relevant populations with existing disease.

Penetration and bactericidal efficacy of two oral care products in an oral biofilm model.

PURPOSE: To investigate the immediate penetration and bactericidal effect of two oral care products marketed in China on an intact natural plaque biofilm model at different time points. METHODS: Eight subjects (aged 20 to 30 years; Turesky Plaque Index Score 2 to 3) were enrolled in the study according to the inclusion criteria. Plaque accumulators were worn by the subjects for 6 and 48 hours for harvesting the dental biofilm. Then the biofilms from different groups were stained with the LIVE/DEAD BacLight fluorescence system to investigate the changes in thickness and fluorescence intensity of living bacteria in biofilm 5 and 15 minutes post-treatment with a mouthrinse containing 0.074% cetylpyridinium chloride (1-minute treatment) or a toothpaste supernatant containing 1.16% stannous chloride (2-minute treatment). In addition, a specific Sn2+ probe was utilized to evaluate the penetration of Sn2+ in the biofilm. Fluorescent images were collected using confocal laser scanning microscopy. Analysis of covariance was used for statistical analyses. All comparisons were two-sided using a 5% level of significance. RESULTS: The thickness of generated plaque biofilm increased gradually from 7.352±4.22 µm at 6 hours to 16.73±7.38 µm at 48 hours (P< 0.05), whereas the thickness and fluorescence intensity of living bacteria stayed unchanged over time. After the treatment of toothpaste supernatant, the ratios of living bacteria thickness and fluorescence intensity of 6- and 48-hour plaque biofilm were significantly decreased (P< 0.05). Treatment of mouthrinse reduced the ratio of living bacteria thickness, but showed no significant impact on overall fluorescence intensity of living bacteria. For 48-hour biofilm, toothpaste supernatant significantly reduced fluorescence intensity of living bacteria from outer layer through inner layer, whereas the mouthrinse showed bactericidal effect only in the outer layer and middle layer. A wide distribution of Sn2+ was shown in the biofilm with the treatment of the tested toothpaste. CLINICAL SIGNIFICANCE: This biofilm model proved to be useful and appropriate for pre-clinical testing of anti-plaque agents. A brief exposure of the biofilm to the tested toothpaste produced significant losses in bacteria viability across outer-middle-inner layers. The tested mouthrinse exerted its bactericidal effect mostly in outer and middle layers of biofilm. The penetration of Sn2+ in the biofilm performed an important function in the bactericidal effect of the toothpaste.

Clinical effect of a manual toothbrush with tapered filaments on dental plaque and gingivitis reduction.

PURPOSE: To evaluate the anti-plaque efficacy (Study 1) and the anti-gingivitis efficacy (Study 2) of a manual toothbrush with tapered bristles compared to marketed control manual toothbrushes. METHODS: Studies 1 and 2 were independent, randomized and controlled, single-center, examiner-blind clinical trials in generally healthy adults. Study 1 included a 2-day acclimation period, followed by a 5-day twice daily toothbrushing test phase with the assigned brush. Baseline and Day 5 pre- and post-brushing plaque levels were assessed via Turesky Modified Quigley-Hein Plaque Index (TMQHPI). In Study 2, subjects with existing gingivitis brushed with their assigned toothbrush twice daily for 4 weeks. Gingivitis was measured using the Mazza Modification of the Papillary Bleeding Index at Baseline and Weeks 2 and 4. In both trials, subjects were randomly assigned to either the manual toothbrush with tapered bristles (Oral-B Super Thin Indicator toothbrush, OM159) or the marketed control (Study 1: Oral-B Complete Clean & Sensitive toothbrush; Study 2: Crest Pro-Health Complete 7 Brush 35 toothbrush) for use with a regular fluoridated dentifrice. RESULTS: 40 (Study 1) and 63 (Study 2) subjects were randomized in each trial. In Study 1, both the tapered bristle and marketed control brushes provided significant (P< 0.0001) mean whole mouth plaque reductions at Day 1 and Day 5 post-brushing relative to pre-brushing as measured via TMQPHI, with no between-brush significant differences. Both groups showed a significant reduction in Day 5 post-brushing mean plaque scores versus Day 1 pre- brushing mean plaque scores (P< 0.0001), but the reductions were not significantly different between groups (P= 0.4274). In Study 2, both the tapered bristle brush and the marketed control brush produced significant (P< 0.0001) reductions in both gingivitis and number of gingival bleeding sites at both Weeks 2 and 4 versus baseline. At Week 4, the tapered filament toothbrush group showed 8.6% less gingivitis (P= 0.0017) and 33.4% fewer bleeding sites (P= 0.0030) versus the control brush. All toothbrushes were well-tolerated. CLINICAL SIGNIFICANCE: Twice daily customary use of a manual toothbrush with tapered bristles provided clinically meaningful plaque and gingivitis reduction benefits.

Cetylpyridinium chloride mouth rinses alleviate experimental gingivitis by inhibiting dental plaque maturation.

Oral rinses containing chemotherapeutic agents, such as cetylpyridinium chloride (CPC), can alleviate plaque-induced gingival infections, but how oral microbiota respond to these treatments in human population remains poorly understood. Via a double-blinded, randomised controlled trial of 91 subjects, the impact of CPC-containing oral rinses on supragingival plaque was investigated in experimental gingivitis, where the subjects, after a 21-day period of dental prophylaxis to achieve healthy gingivae, received either CPC rinses or water for 21 days. Within-subject temporal dynamics of plaque microbiota and symptoms of gingivitis were profiled via 16S ribosomal DNA gene pyrosequencing and assessment with the Mazza gingival index. Cetylpyridinium chloride conferred gingival benefits, as progression of gingival inflammation resulting from a lack of dental hygiene was significantly slower in the mouth rinse group than in the water group due to inhibition of 17 gingivitis-enriched bacterial genera. Tracking of plaque α and ß diversity revealed that CPC treatment prevents acquisition of new taxa that would otherwise accumulate but maintains the original biodiversity of healthy plaques. Furthermore, CPC rinses reduced the size, local connectivity and microbiota-wide connectivity of the bacterial correlation network, particularly for nodes representing gingivitis-enriched taxa. The findings of this study provide mechanistic insights into the impact of oral rinses on the progression and maturation of dental plaque in the natural human population.

Microbiota-based Signature of Gingivitis Treatments: A Randomized Study.

Plaque-induced gingivitis can be alleviated by various treatment regimens. To probe the impacts of various anti-gingivitis treatments on plaque microflora, here a double blinded, randomized controlled trial of 91 adults with moderate gingivitis was designed with two anti-gingivitis regimens: the brush-alone treatment and the brush-plus-rinse treatment. In the later group, more reduction in both Plaque Index (TMQHI) and Gingival Index (mean MGI) at Day 3, Day 11 and Day 27 was evident, and more dramatic changes were found between baseline and other time points for both supragingival plaque microbiota structure and salivary metabonomic profiles. A comparison of plaque microbiota changes was also performed between these two treatments and a third dataset where 50 subjects received regimen of dental scaling. Only Actinobaculum, TM7 and Leptotrichia were consistently reduced by all the three treatments, whereas the different microbial signatures of the three treatments during gingivitis relieve indicate distinct mechanisms of action. Our study suggests that microbiota based signatures can serve as a valuable approach for understanding and potentially comparing the modes of action for clinical treatments and oral-care products in the future.

A randomized 3-month clinical comparison of a power toothbrush to a manual toothbrush in the reduction of gingivitis.

PURPOSE: To compare the anti-gingivitis effect of a power toothbrush relative to a manual toothbrush control. METHODS: This was a 3-month, randomized and controlled, single-center, parallel group, examiner-blinded clinical study. 123 Chinese adults in good general health and with at least 15 gingival bleeding sites, as measured by the Gingival Bleeding Index, were enrolled into the study. At baseline, pre-treatment gingivitis levels were assessed using the Mazza Bleeding Index. Subjects were then randomly assigned to receive either an oscillating-rotating power toothbrush [Oral-B Professional Care 7000 (D17u/EB17)] or a flat-trim manual toothbrush with tapered filaments (Lion Dentor Systema). Subjects brushed at home twice-daily with their assigned toothbrush and a marketed sodium fluoride dentifrice (Crest Cavity Protection dentifrice), and were reevaluated at Months 1, 2, and 3. RESULTS: 113 evaluable subjects completed the study. Both groups showed significant reductions in gingivitis from baseline for all time points measured (P< 0.001). At Months 1, 2 and 3, the power toothbrush demonstrated significantly greater gingivitis reductions of 7.11%, 9.20% and 8.47%, respectively, than the manual toothbrush (P< 0.01), and significantly fewer bleeding sites (17.3%, 23.9% and 24.3%, respectively, P< 0.05). No adverse events were reported or observed for either brush during the study. CLINICAL SIGNIFICANCE: The power brush provided statistically significantly greater reductions in gingivitis compared with a manual toothbrush at Months 1, 2 and 3.

An ancestral role in peroxisome assembly is retained by the divisional peroxin Pex11 in the yeast Yarrowia lipolytica.

The peroxin Pex11 has a recognized role in peroxisome division. Pex11p remodels and elongates peroxisomal membranes prior to the recruitment of dynamin-related GTPases that act in membrane scission to divide peroxisomes. We performed a comprehensive comparative genomics survey to understand the significance of the evolution of the Pex11 protein family in yeast and other eukaryotes. Pex11p is highly conserved and ancestral, and has undergone numerous lineage-specific duplications, whereas other Pex11 protein family members are fungal-specific innovations. Functional characterization of the in-silico-predicted Pex11 protein family members of the yeast Yarrowia lipolytica, i.e. Pex11p, Pex11Cp and Pex11/25p, demonstrated that Pex11Cp and Pex11/25p have a role in the regulation of peroxisome size and number characteristic of Pex11 protein family members. Unexpectedly, deletion of PEX11 in Y. lipolytica produces cells that lack morphologically identifiable peroxisomes, mislocalize peroxisomal matrix proteins and preferentially degrade peroxisomal membrane proteins, i.e. they exhibit the classical pex mutant phenotype, which has not been observed previously in cells deleted for the PEX11 gene. Our results are consistent with an unprecedented role for Pex11p in de novo peroxisome assembly.

Dynein light chain interaction with the peroxisomal import docking complex modulates peroxisome biogenesis in yeast.

Dynein is a large macromolecular motor complex that moves cargo along microtubules. A motor-independent role for the light chain of dynein, Dyn2p, in peroxisome biology in Saccharomyces cerevisiae was suggested from its interaction with Pex14p, a component of the peroxisomal matrix protein import docking complex. Here we show that cells of the yeast Yarrowia lipolytica deleted for the gene encoding the homologue of Dyn2p are impaired in peroxisome function and biogenesis. These cells exhibit compromised growth on medium containing oleic acid as the carbon source, the metabolism of which requires functional peroxisomes. Their peroxisomes have abnormal morphology, atypical matrix protein localization, and an absence of proteolytic processing of the matrix enzyme thiolase, which normally occurs upon its import into the peroxisome. We also show physical and genetic interactions between Dyn2p and members of the docking complex, particularly Pex17p. Together, our results demonstrate a role for Dyn2p in the assembly of functional peroxisomes and provide evidence that Dyn2p acts in cooperation with the peroxisomal matrix protein import docking complex to effect optimal matrix protein import.

Two-week extrinsic stain removal efficacy of a sodium fluoride dentifrice with high cleaning silica: results from two randomized, controlled clinical trials.

PURPOSE: To evaluate a stannous-containing sodium fluoride dentifrice with high cleaning silica and polychelation technology (test dentifrice) compared to a currently marketed whitening dentifrice, which carries the ADA Seal of Acceptance for whitening, for its efficacy in removing existing natural stain over a 2-week period. METHODS: Two independent, randomized, positive-controlled, 2-treatment, parallel group, double-blind, 2-week studies with identical protocols were conducted in China. At baseline, subjects received an oral soft tissue (OST) examination followed by a Lobene stain examination. In each study, approximately 60 subjects having a Lobene stain composite score above 1 were randomized to one of two dentifrice products: the test dentifrice or the positive control. Subjects were instructed to brush twice daily for at least 1 minute with their assigned product. Lobene stain and OST examinations were conducted again after 2 weeks of use. RESULTS: In both studies, the test dentifrice and the positive control dentifrice demonstrated statistically significant reductions in Lobene composite (P<0.0001), area (P<0.0001) and intensity (P<0.0001) stain scores after 2 weeks of use versus baseline. At Week 2, there were no statistically significant differences in stain scores between treatment groups in either study (P>0.12).

Clinical evaluation of the fast onset and sustained sensitivity relief of a 0.454% stannous fluoride dentifrice compared to an 8.0% arginine-calcium carbonate-sodium monofluorophosphate dentifrice.

PURPOSE: To evaluate the efficacy of a dentifrice containing 0.454% stannous fluoride (SnF2) in the reduction of dentin hypersensitivity immediately after use, after 3 days and after a 2-week use period as compared to a positive control dentifrice containing 8.0% arginine, calcium carbonate and 1450 ppm fluoride as sodium monofluorophosphate. METHODS: 80 healthy adult subjects with moderate dentin hypersensitivity were enrolled in this clinical study, which had a controlled, randomized, examiner-blind, two-treatment (40 subjects per treatment group), parallel group design. For each subject, two sensitive bicuspid or cuspid teeth in different quadrants demonstrating reproducible sensitivity to thermal stimuli (Schiff air sensitivity score of > 1) were chosen for evaluation. Subjects were randomized to treatment with either the SnF2 dentifrice or the positive control dentifrice. At the baseline visit, subjects were assessed for sensitivity to thermal stimuli, received an oral soft tissue examination, and were instructed to brush with their assigned dentifrice according to manufacturers' usage instructions. Immediately after brushing, sensitivity to thermal stimuli for each enrolled tooth was assessed by an experienced dental examiner using the Schiff air sensitivity index and by study subjects based on air visual analog scale (VAS). After using their assigned dentifrice for 3 days and for 2 weeks, thermal sensitivity was re-assessed by both examiner and subject, and each subject received an oral soft tissue examination. RESULTS: 40 subjects in the SnF2 dentifrice group and 38 subjects in the control group completed all study procedures. Both dentifrice groups showed significant sensitivity relief relative to baseline (P < 0.01). The SnF2 dentifrice provided a statistically significant (P = 0.005) 7.4% reduction in sensitivity relative to the positive control dentifrice immediately after first use and an even more significant (P = 0.001) 20% reduction at Week 2 based on the Schiff air sensitivity scale. Based on the VAS, the SnF2 dentifrice provided statistically significant (P < 0.0001) reduction in sensitivity relative to the positive control dentifrice immediately after first use, at Day 3, and Week 2, with percent reductions of 7.2%, 15.8% and 28.2%, respectively. No adverse events were reported with either dentifrice.

Pex3 peroxisome biogenesis proteins function in peroxisome inheritance as class V myosin receptors.

In Saccharomyces cerevisiae, peroxisomal inheritance from mother cell to bud is conducted by the class V myosin motor, Myo2p. However, homologues of S. cerevisiae Myo2p peroxisomal receptor, Inp2p, are not readily identifiable outside the Saccharomycetaceae family. Here, we demonstrate an unexpected role for Pex3 proteins in peroxisome inheritance. Both Pex3p and Pex3Bp are peroxisomal integral membrane proteins that function as peroxisomal receptors for class V myosin through direct interaction with the myosin globular tail. In cells lacking Pex3Bp, peroxisomes are preferentially retained by the mother cell, whereas most peroxisomes gather and are transferred en masse to the bud in cells overexpressing Pex3Bp or Pex3p. Our results reveal an unprecedented role for members of the Pex3 protein family in peroxisome motility and inheritance in addition to their well-established role in peroxisome biogenesis at the endoplasmic reticulum. Our results point to a temporal link between peroxisome formation and inheritance and delineate a general mechanism of peroxisome inheritance in eukaryotic cells.

Peroxisomal peripheral membrane protein YlInp1p is required for peroxisome inheritance and influences the dimorphic transition in the yeast Yarrowia lipolytica.

Eukaryotic cells have evolved molecular mechanisms to ensure the faithful inheritance of organelles by daughter cells in order to maintain the benefits afforded by the compartmentalization of biochemical functions. Little is known about the inheritance of peroxisomes, organelles of lipid metabolism. We have analyzed peroxisome dynamics and inheritance in the dimorphic yeast Yarrowia lipolytica. Most peroxisomes are anchored at the periphery of cells of Y. lipolytica. In vivo video microscopy showed that at cell division, approximately half of the anchored peroxisomes in the mother cell are dislodged individually from their static positions and transported to the bud. Peroxisome motility is dependent on the actin cytoskeleton. YlInp1p is a peripheral peroxisomal membrane protein that affects the partitioning of peroxisomes between mother cell and bud in Y. lipolytica. In cells lacking YlInp1p, most peroxisomes were transferred to the bud, with only a few remaining in the mother cell, while in cells overexpressing YlInp1p, peroxisomes were preferentially retained in the mother cell, resulting in buds nearly devoid of peroxisomes. Our results are consistent with a role for YlInp1p in anchoring peroxisomes in cells. YlInp1p has a role in the dimorphic transition in Y. lipolytica, as cells lacking the YlINP1 gene more readily convert from the yeast to the mycelial form in oleic acid-containing medium, the metabolism of which requires peroxisomal activity, than does the wild-type strain. This study reports the first analysis of organelle inheritance in a true dimorphic yeast and identifies the first protein required for peroxisome inheritance in Y. lipolytica.