Anatomical consideration of ultrasonography-guided intraoral injection for temporal tendinitis.

Temporal tendinitis is characterized by acute inflammation often resulting from mechanical stress, such as repetitive jaw movements associated with jaw opening and closing and teeth clenching. Treatment for temporal tendinitis typically involves the administration of local anesthetic or corticosteroid injections. However, the complex anatomical structure of the coronoid process, to which the temporalis tendon attaches, located deep within the zygomatic arch, poses challenges for accurate injections. In this study, we aimed to establish guidelines for the safe and effective treatment of temporal tendinitis by using intraoral ultrasonography (US) to identify the anatomical structures surrounding the temporalis tendon and coronoid process. US was performed using an intraoral transducer on 58 volunteers without temporomandibular joint disease. The procedure involved placing the transducer below the occlusal plane of the maxillary second molar. Measurements were taken for the horizontal distance from the anterior border of the coronoid process, observed at the midpoint (MP) of the US images, and the depth of the coronoid process and temporalis muscle from the oral mucosa. The anterior border of the coronoid process was visualized on all US images and classified into three observed patterns at the MP: type A (anterior to the MP, 56.2%), type B (at the MP, 16.1%), and type C (posterior to the MP, 27.7%). The temporalis muscle was located at a mean depth of 3.12 ± 0.68 mm from the oral mucosa. The maxillary second molar is an intraoral landmark for visualizing the anterior border of the coronoid process. The new location information obtained using intraoral US could help identify the safest and most effective injection sites for the treatment of temporal tendinitis.

What is a superior labial frenulum? An anatomical and histological study.

Anatomy of the superior labial frenulum (SLF), at first glance, seems to be well established. However, existing studies on the SLF lack description of the incisivus labii superioris (ILS), which cannot be ignored when discussing the SLF. We believe that thorough understanding of the SLF necessitates the anatomical knowledge of the ILS. This study aimed to elucidate the anatomical relationship between the orbicularis oris (OO), ILS, and SLF. A total of 20 formalin fixed human cadaveric specimens were used for gross anatomical and/or histological observation. For histological observation, all specimens were stained with Masson-trichrome. The SLF was a mucosal fold between the gingival mucosa and alveolar mucosa with connective tissue deep to it. The connective tissue attached to the alveolar bone in the junction between the right and left ILS. Skeletal muscle fibers other than orbicularis oris was found in one specimen, which were considered the ILS. During a frenulectomy, removal of the connective tissue bundle is required to prevent recurrence of the high SLF insertion.

Sonoanatomy of the platysmal bands: What causes the platysmal band?

BACKGROUND: The platysmal band is created by the platysma muscle, a thin superficial muscle that covers the entire neck and the lower part of the face. The platysmal band appears at the anterior and posterior borders of the muscle. To date, no definite pathophysiology has been established. Here, we observed a lack of knowledge of the anatomy of the platysma muscle using ultrasonography in this study. METHODS: We conducted a descriptive, prospective study observing the platysmal band in resting and contraction states to reveal muscle changes. Twenty-four participants (aged 23-57 years) with anterior and posterior neck bands underwent ultrasonography in resting and contracted states. Ten cadavers were studied aged 67-85 years to measure the thickness of the platysma muscle at 12 points: horizontally (medial, middle, lateral) and vertically (inferior mandibular margin, hyoid bone, cricoid cartilage, superior margin of clavicle). RESULTS: The anterior and posterior borders of the platysma muscle were thicker than the middle of the platysma muscle when in a contracted state, and the muscle also had a convex shape when contracted. The thickness of the platysma muscle was not significantly different over 12 points in the resting state. During contraction, the platysma muscles contracted in the medial and lateral margins of the muscle, which was more significant in the posterior bands. CONCLUSION: The anterior and posterior platysmal bands are related to muscle thickness during contraction. These observations support the change in platysmal band treatment only at the anterior and posterior border of the muscle.

Positional deformation of the parotid gland: Application to minimally invasive procedures.

Anatomical studies of the parotid gland are important for mid- and lower face filler, botulinum toxin, and thread lifting procedures. The purpose of this study was to observe the topographic anatomy of the parotid gland using cadaveric dissections. The superficial lobe of the parotid gland was studied in 30 hemisected heads. Reference lines were made on the lateral aspect of the face. A reference line (the line connecting the mandibular angle to the upper margin of the zygomatic arch, along the posterior border of the ramus) was divided into four sections (P1, P2, P3, and P4). The superior, inferior, anterior, and posterior borders of the parotid gland were measured using the reference lines and sections. Using these measurements, we categorized the superficial lobe of the parotid gland into two types: type Ia, pistol-shaped; Ib, pistol-shaped with an accessory lobe; and type II, oval-shaped. The superior border of the parotid gland started just below the inferior margin of the zygomatic arch. The parotid gland covered the posterior part of the masseter muscle near P1 and P2, but at P3 and below P3, the tail of the parotid gland was located posterior to the ramus and covered the anterior part of the sternocleidomastoid muscle. The topographic anatomy of the parotid gland serves as a reliable reference for esthetic procedures in the lower face and neck region.

Easy three-dimensional scanning technology for anatomy education using a free cellphone app.

The COVID-19 pandemic has brought difficult times to anatomy educators and medical/dental students. Under normal circumstances, gross anatomy classes give students opportunities to touch and observe human bones and cadaveric tissues, thus enhancing their understanding; such morphology is difficult to learn from textbooks alone. As many studies have shown, three-dimensional (3D) technologies used in online lectures can serve as alternatives to real specimens for providing knowledge of anatomy. However, such technologies are often expensive. The goal of this study was to create 3D anatomy models for online lectures using a free cellphone app. Free application software (Qlone) was used to create 3D anatomical models. The extracranium and intracranium of adult skull, fetal skull, mandible, temporal bone, second cervical vertebra, and ilium were all scanned and exported to the computer in 3D format. A total of 53 anatomical structures were evaluated by nine observers. Although the 53 structures used in this study did not include all the structures that students need to learn, visibility was good/acceptable for most of the 53. The free and simple 3D scanning app used in this study could enable anatomy educators to provide better content to students during online lectures.

Imparting High Proton Conductivity to Nafion® Tuned by Acidic Chitosan for Low-Temperature Proton Exchange Membrane Fuel Cell Applications.

A successful polymer electrolyte membrane for fuel cell application must have efficient proton conductivity as well as good water retention capability. The viability of using composite membranes prepared by blending 85% deacetylated chitosan (CS) and Nafion® in proton exchange membrane fuel cells (PEMFCs) was investigated based on the concept of hydrophilicity and the water uptake characteristics of CS. These membranes were characterized by infrared spectroscopy and field-emission scanning electron microscopy to investigate their intermolecular interactions and morphology, respectively. Absorption studies were carried out to evaluate the interactions of the membranes with water. Titrimetric ion exchange capacity analysis indicated the availability of active sites in the membrane. The CS/Nafion® blend was found to be suitable for PEMFC applications because of its relatively high proton conductivity compared to that of regular Nafion®. Above all, the cost-effectiveness and simple fabrication of such composite membranes make their use in low-temperature PEMFCs very attractive and economical.

Anesthetic efficacy of an inferior alveolar nerve block in soft tissue and correlation between soft tissue and pulpal anesthesia.

OBJECTIVES: This study was aimed at evaluating the anesthetic success rates in various regions of soft tissue after inferior alveolar nerve (IAN) block and comparing the success rates of soft tissue anesthesia with those of pulpal anesthesia to find correlations. MATERIALS AND METHODS: Fifty-nine dental students received an IAN block injection. A total of four test sites were used for soft tissue anesthesia using a pressure algometer (PA): the corner of the lower lip vermilion border (LL); the buccal-attached gingiva of the lateral incisor (BGI), the molar (BGM), and the lingual gingiva (LG). The lateral incisor (LI) and the first molar (M1) were evaluated for pulpal anesthesia using an electric pulp tester. To evaluate whether soft tissue anesthesia can be an indicator of pulpal anesthesia, the positive predictive value (PPV) and negative predictive value (NPV) were calculated. RESULTS: The highest success rate for soft tissue anesthesia was seen on the LG (93.9%), followed by LL (79.6%), BGI (53.1%), and BGM (14.3%). The PPVs of LL for the M1 and Ll were 74.4 and 59.0%. The NPVs for the M1 and LI were much higher in the LL (90.0 and 100%, respectively) than in the BGI (56.5 and 69.6%, respectively). CONCLUSIONS: The highest success rate was found in the LG. Lip numbness was not an indicator of pulpal anesthesia of M1 and LI. However, if the LL was not anesthetized, the probabilities of failed pulpal anesthesia were very high in the LI and M1. CLINICAL RELEVANCE: The clinicians need to consider not doing an additional lingual nerve block after IAN block.

Functionalized Magnetic PLGA Nanospheres for Targeting and Bioimaging of Breast Cancer.

Superparamagnetic iron oxide nanoparticles (SPIONs) are actively used as highly sensitive imaging probes to provide contrast in MRI. In this study, we propose the use of SPIONs encapsulated with antibody-conjugated poly(lactic-co-glycolic acid) (PLGA) as a potent theragnostic agent. The SPIONs were synthesized by a chemical co-precipitation method of ferric and ferrous ions, and subsequently encapsulated with PLGA by using an emulsification-diffusion method. Herceptin was chemically conjugated to the SPION-encapsulating PLGA nanoparticles to target the human epidermal growth factor receptor 2 (Her2/neu) overexpressing breast cancers. FACS and MR molecular imaging revealed that the Her2/neu overexpressing cell line showed a stronger contrast enhancement than the Her2/neu non-expressing cell lines, and the signal intensity of in vivo MR imaging decreased as the concentration of Herceptin increased. This strategy of encapsulating SPIONs with PLGA will be highly useful in functionalizing magnetic nanoparticles and improving the diagnostic and therapeutic efficacy of a wide array of cancer treatments.

New Insight Regarding the Zygomaticus Minor as Related to Cosmetic Facial Injections.

The present study aimed to determine the arrangement and terminal attachments of the zygomaticus minor (Zmi) muscle fibers connecting the orbital and mouth regions. The Zmi was examined in 32 specimens of embalmed Korean adult cadavers. The Zmi was present in all 32 specimens (100%). In 31 of the specimens (96.9%), the Zmi that inserted into the upper lip was formed by muscle fibers that arose from the zygomatic bone and muscle fibers that extended from the orbicularis oculi (OOc) muscle. In 14 of the specimens (43.8%), some fibers of the Zmi that arose from the zygomatic bone blended with the inferior margin of the OOc, while the other fibers inserted into the upper lip. After the Zmi fibers blended with the inferior margin of the OOc, these fibers constituted the inferior and medial margins of the OOc. These fibers were then attached to the medial palpebral ligament, the maxilla, the levator labii superioris alaeque nasi muscle, and the depressor supercilii muscle. In 30 of 32 specimens (93.8%), muscle fibers that extended from the OOc constituted the lateral margin of the Zmi, usually descending to the level between the nasal ala and the vermilion border of the upper lip and inserting into the upper lip. The obtained data will be helpful for understanding their connected movements and in kinematics and electromyographic analyses, therapies involving injections of botulinum toxin Type A, and various types of facial surgery. Clin. Anat. 31:974-980, 2018. © 2018 Wiley Periodicals, Inc.

Ring Opening Metathesis Polymerization of Bicyclic α,ß-Unsaturated Anhydrides for Ready-to-be-grafted Polymers Having Tailored pH-Responsive Degradability.

Polymers having α,ß-unsaturated anhydrides as repeating units were synthesized by ring opening metathesis polymerization (ROMP). The anhydride moieties were ready-to-be-grafted with amines to form acid-labile cis-α,ß-unsaturated acid amide linkages. The pH-responsive reversible de-grafting can be controlled by changing the intramolecular accessibility between acid and amide groups. The alendronate-grafted ROMP polymers showed distinct pH-dependent cytotoxicity according to the anhydride structures.

Metabolic engineering of a haploid strain derived from a triploid industrial yeast for producing cellulosic ethanol.

Many desired phenotypes for producing cellulosic biofuels are often observed in industrial Saccharomyces cerevisiae strains. However, many industrial yeast strains are polyploid and have low spore viability, making it difficult to use these strains for metabolic engineering applications. We selected the polyploid industrial strain S. cerevisiae ATCC 4124 exhibiting rapid glucose fermentation capability, high ethanol productivity, strong heat and inhibitor tolerance in order to construct an optimal yeast strain for producing cellulosic ethanol. Here, we focused on developing a general approach and high-throughput screening method to isolate stable haploid segregants derived from a polyploid parent, such as triploid ATCC 4124 with a poor spore viability. Specifically, we deleted the HO genes, performed random sporulation, and screened the resulting segregants based on growth rate, mating type, and ploidy. Only one stable haploid derivative (4124-S60) was isolated, while 14 other segregants with a stable mating type were aneuploid. The 4124-S60 strain inherited only a subset of desirable traits present in the parent strain, same as other aneuploids, suggesting that glucose fermentation and specific ethanol productivity are likely to be genetically complex traits and/or they might depend on ploidy. Nonetheless, the 4124-60 strain did inherit the ability to tolerate fermentation inhibitors. When additional genetic perturbations known to improve xylose fermentation were introduced into the 4124-60 strain, the resulting engineered strain (IIK1) was able to ferment a Miscanthus hydrolysate better than a previously engineered laboratory strain (SR8), built by making the same genetic changes. However, the IIK1 strain showed higher glycerol and xylitol yields than the SR8 strain. In order to decrease glycerol and xylitol production, an NADH-dependent acetate reduction pathway was introduced into the IIK1 strain. By consuming 2.4g/L of acetate, the resulting strain (IIK1A) exhibited a 14% higher ethanol yield and 46% lower byproduct yield than the IIK1 strain from anaerobic fermentation of the Miscanthus hydrolysate. Our results demonstrate that industrial yeast strains can be engineered via haploid isolation. The isolated haploid strain (4124-S60) can be used for metabolic engineering to produce fuels and chemicals.

Fourier Transform Infrared Spectroscopy (FT-IR) and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Developmental Cotton Fibers.

With cotton fiber growth or maturation, cellulose content in cotton fibers markedly increases. Traditional chemical methods have been developed to determine cellulose content, but it is time-consuming and labor-intensive, mostly owing to the slow hydrolysis process of fiber cellulose components. As one approach, the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy technique has also been utilized to monitor cotton cellulose formation, by implementing various spectral interpretation strategies of both multivariate principal component analysis (PCA) and 1-, 2- or 3-band/-variable intensity or intensity ratios. The main objective of this study was to compare the correlations between cellulose content determined by chemical analysis and ATR FT-IR spectral indices acquired by the reported procedures, among developmental Texas Marker-1 (TM-1) and immature fiber (im) mutant cotton fibers. It was observed that the R value, CIIR, and the integrated intensity of the 895 cm-1 band exhibited strong and linear relationships with cellulose content. The results have demonstrated the suitability and utility of ATR FT-IR spectroscopy, combined with a simple algorithm analysis, in assessing cotton fiber cellulose content, maturity, and crystallinity in a manner which is rapid, routine, and non-destructive.

Dental optical coherence tomography: new potential diagnostic system for cracked-tooth syndrome.

PURPOSE: The aim of the present study was to determine the reliability of optical coherence tomography (OCT) in detecting cracked teeth and its relative clinical effectiveness by comparing it with other diagnostic methods including conventional visual inspection, trans-illumination, and micro-computed tomography (micro-CT). METHODS: The reliability of swept source OCT (SS-OCT) was verified by comparing the number of detected crack lines on 109 surfaces of 61 teeth with those detected with other conventional methods. RESULTS: One to one comparison revealed that crack lines that were invisible with naked eyes could be found in SS-OCT images. The detection ability of SS-OCT was superior or similar to those of micro-CT (100.0 %) and trans-illumination. CONCLUSIONS: Crack lines shown in the SS-OCT images had distinct characteristics, and structural crack lines and craze lines could be distinguished in SS-OCT images. Thus, the detection ability of SS-OCT renders it an acceptable diagnostic device for cracked-tooth syndrome.

Revisiting the Topographic Anatomy of the Marginal Mandibular Branch of Facial Nerve Relating to the Surgical Approach.

BACKGROUND: The marginal mandibular branch (Mbr) of the facial nerve is vulnerable to damage during rhytidoplasty, surgical reduction of the mandibular angle, parotidectomy, and excision of the submandibular gland. OBJECTIVES: The authors sought to map the Mbr and determine the relationship between the number of Mbr offshoots and the course of the Mbr. METHODS: The Mbr was examined in 29 hemifaces from 12 embalmed and 4 fresh cadavers (10 males, 6 females; mean age, 73.7 years). RESULTS: The Mbr was located ≤5 mm from the gonion (Go) in 24 of 29 hemifaces (82.8%) and ≤10 mm from the intersection of the facial artery and mandible (ie, FM) in 26 hemifaces (89.7%). In 16 hemifaces (55.2%), offshoots arose from the Mbr inferior to the mandible. The Mbr ran below the Go in 14 hemifaces (48.3%) and ran below FM in 13 hemifaces (44.8%). Except for minute offshoots deep to the platysma, the Mbr was not found to pass >2 cm below the mandible. The mean (± standard deviation) quantity of Mbr offshoots was 1.5 (± 0.6). A greater number of offshoots was associated with a higher likelihood of an inferiorly located nerve. The Mbr proceeded under the lower border of the mandible in 13 hemifaces (44.8%) and reached the mandible at a mean distance of 33.1±5.2 mm anterior to the Go. CONCLUSIONS: To avoid damaging the Mbr, surgical maneuvers should be positioned 4.5 cm anterior to the Go and 2 cm below the mandible.

Anatomic Study of the Dorsalis Pedis Artery, First Metatarsal Artery, and Second Metatarsal Bone for Mandibular Reconstruction.

PURPOSE: The purpose of this study was to clarify the anatomic variation of the dorsalis pedis and first metatarsal arteries and to define the trabecular-to-cortical bone ratio (TBR) of the second metatarsal bone to ascertain their suitability as implants. MATERIALS AND METHODS: Fifty-two specimens were prepared for this study. Each specimen was dissected on the dorsal side of the foot to search for the dorsalis pedis artery. RESULTS: Three types of dorsalis pedis artery were found: in type A, which was the most common, the artery continuously formed the first metatarsal artery; in type C, which was the second most common, the artery coursed below the first dorsal interosseous muscle; and in type B, the artery coursed from the lateral side. Five variations of the first metatarsal artery were identified: the most common was type IIb, in which the artery coursed below the first dorsal interosseous muscle; followed by type Ib, in which the artery coursed obliquely through the muscle; type Ic, in which the artery coursed parallel to the muscle; type IIa, in which the artery coursed above and below the muscle; and type Ia, in which the artery coursed only above the muscle. The second metatarsal bone was divided into 5 regions. There was no trabecular bone in regions 1 and 5. The TBR appeared to be lower in region 3 than in regions 2 and 4 and highest in region 2. CONCLUSION: All regions of the second metatarsal bone appear to be suitable as implants, but when placing the implant in the proximal end, care should be taken not to overheat the bone and to be wary of perforation when placing it on the middle side.

Quantitative anatomical analysis of facial expression using a 3D motion capture system: Application to cosmetic surgery and facial recognition technology.

The topography of the facial muscles differs between males and females and among individuals of the same gender. To explain the unique expressions that people can make, it is important to define the shapes of the muscle, their associations with the skin, and their relative functions. Three-dimensional (3D) motion-capture analysis, often used to study facial expression, was used in this study to identify characteristic skin movements in males and females when they made six representative basic expressions. The movements of 44 reflective markers (RMs) positioned on anatomical landmarks were measured. Their mean displacement was large in males [ranging from 14.31 mm (fear) to 41.15 mm (anger)], and 3.35-4.76 mm smaller in females [ranging from 9.55 mm (fear) to 37.80 mm (anger)]. The percentages of RMs involved in the ten highest mean maximum displacement values in making at least one expression were 47.6% in males and 61.9% in females. The movements of the RMs were larger in males than females but were more limited. Expanding our understanding of facial expression requires morphological studies of facial muscles and studies of related complex functionality. Conducting these together with quantitative analyses, as in the present study, will yield data valuable for medicine, dentistry, and engineering, for example, for surgical operations on facial regions, software for predicting changes in facial features and expressions after corrective surgery, and the development of face-mimicking robots.

Neurovascular structures of the mandibular angle and condyle: a comprehensive anatomical review.

BACKGROUND: Various surgical interventions including esthetic surgery, salivary gland excision, and open reduction of fracture have been performed in the area around the mandibular angle and condyle. This study aimed to comprehensively review the anatomy of the neurovascular structures on the angle and condyle with recent anatomic and clinical research. METHODS AND RESULTS: We provide detailed information about the branching and distributing patterns of the neurovascular structures at the mandibular angle and condyle, with reported data of measurements and proportions from previous anatomical and clinical research. Our report should serve to help practitioners gain a better understanding of the area in order or reduce potential complications during local procedures. Reckless manipulation during mandibular angle reduction could mutilate arterial branches, not only from the facial artery, but also from the external carotid artery. The transverse facial artery and superficial temporal artery could be damaged during approach and incision in the condylar area. The marginal mandibular branch of the facial nerve can be easily damaged during submandibular gland excision or facial rejuvenation treatment. The main trunk of the facial nerve and its upper and lower distinct divisions have been damaged during parotidectomy, rhytidectomy, and open reductions of condylar fractures. CONCLUSION: By revisiting the information in the present study, surgeons will be able to more accurately prevent procedure-related complications, such as iatrogenic vascular accidents on the mandibular angle and condyle, complete and partial facial palsy, gustatory sweating (Frey syndrome), and traumatic neuroma after parotidectomy.

What is the difference between the inferior labial artery and the horizontal labiomental artery?

BACKGROUND: The inferior labial artery (ILA) and horizontal labiomental artery (HLA) can be regarded as the main arteries used in the lower lip pedicle for the perioral reconstruction. However, the courses of the ILA and HLA are described in diverse ways, and there is no obvious standard for distinguishing between them. The aim of this study was to elucidate the distribution patterns of the ILA and HLA, and the significance of the HLA in the vascularization of the lower lip. MATERIALS AND METHODS: Sixty-three hemifaces from 18 Korean and 19 Thai cadavers were used in this study. The distribution patterns of the arteries of the lower lip area were classified based on the assumption that the HLA travels in the middle of the lower lip area, while the ILA runs along the lower lip border. The arterial distribution pattern of the HLA was classified into three types (I-III): type I, where the HLA ran horizontally in the lower lip area; type II, where the HLA curved upward to the vermilion border of the lower lip; and type III, where the HLA bifurcated into two branches. The ILA was also classified into three types (A-C): type A, where the ILA was not observed; type B, ILA was ramified from facial artery at the level of mouth corner; and type C, ILA arose from the superior labial artery (SLA) and supplied the lower lip vermillion border. RESULTS: Types I, II, and III were observed in 52.4 % (33/63), 39.7 % (25/63), and 7.9 % (5/63) of cases, respectively; and types A, B, and C were observed in 52.4 % (33/63), 36.5 % (23/63), and 11.1 % (7/63) of cases. Consideration of the two artery classifications together revealed seven types: type IA (14.3 %, 9/63), type IB (28.6 %, 18/63), type IC (9.5 %, 6/63), type IIA (30.2 %, 19/63), type IIB (7.9 %, 5/63), type IIC (1.6 %, 1/63), and type III (7.9 %, 5/63). The distance between the HLA and the midpoint between the mouth corner and the inferior mandibular margin was 0.4 ± 3.1 mm (mean ± SD) inferior to this point. CONCLUSION: The ILA and HLA should be differentiated according to the location of their origin rather than their terminating areas. The HLA could be considered as the main artery supplying the lower lip mucosa.

Interactions between Shh, Sostdc1 and Wnt signaling and a new feedback loop for spatial patterning of the teeth.

Each vertebrate species displays specific tooth patterns in each quadrant of the jaw: the mouse has one incisor and three molars, which develop at precise locations and at different times. The reason why multiple teeth form in the jaw of vertebrates and the way in which they develop separately from each other have been extensively studied, but the genetic mechanism governing the spatial patterning of teeth still remains to be elucidated. Sonic hedgehog (Shh) is one of the key signaling molecules involved in the spatial patterning of teeth and other ectodermal organs such as hair, vibrissae and feathers. Sostdc1, a secreted inhibitor of the Wnt and Bmp pathways, also regulates the spatial patterning of teeth and hair. Here, by utilizing maternal transfer of 5E1 (an anti-Shh antibody) to mouse embryos through the placenta, we show that Sostdc1 is downstream of Shh signaling and suggest a Wnt-Shh-Sostdc1 negative feedback loop as a pivotal mechanism controlling the spatial patterning of teeth. Furthermore, we propose a new reaction-diffusion model in which Wnt, Shh and Sostdc1 act as the activator, mediator and inhibitor, respectively, and confirm that such interactions can generate the tooth pattern of a wild-type mouse and can explain the various tooth patterns produced experimentally.

Analysis of cellodextrin transporters from Neurospora crassa in Saccharomyces cerevisiae for cellobiose fermentation.

Saccharomyces cerevisiae can be engineered to ferment cellodextrins produced by cellulases as a product of cellulose hydrolysis. Direct fermentation of cellodextrins instead of glucose is advantageous because glucose inhibits cellulase activity and represses the fermentation of non-glucose sugars present in cellulosic hydrolyzates. To facilitate cellodextrin utilization by S. cerevisiae, a fungal cellodextrin-utilizing pathway from Neurospora crassa consisting of a cellodextrin transporter and a cellodextrin hydrolase has been introduced into S. cerevisiae. Two cellodextrin transporters (CDT-1 and CDT-2) were previously identified in N. crassa, but their kinetic properties and efficiency for cellobiose fermentation have not been studied in detail. In this study, CDT-1 and CDT-2, which are hypothesized to transport cellodextrin with distinct mechanisms, were introduced into S. cerevisiae along with an intracellular ß-glucosidase (GH1-1). Cellobiose transport assays with the resulting strains indicated that CDT-1 is a proton symporter while CDT-2 is a simple facilitator. A strain expressing CDT-1 and GH1-1 (DCDT-1G) showed faster cellobiose fermentation than the strain expressing CDT-2 and GH1-1 (DCDT-2G) under various culture conditions with different medium compositions and aeration levels. While CDT-2 is expected to have energetic benefits, the expression levels and kinetic properties of CDT-1 in S. cerevisiae appears to be optimum for cellobiose fermentation. These results suggest CDT-1 is a more effective cellobiose transporter than CDT-2 for engineering S. cerevisiae to ferment cellobiose.