Sonography of nasal tip anatomy and surgical tip refinement

The amorphous or wide nasal tip is the most commonly encountered nasal tip deformity, but little has been done to measure the effect of standard rhinoplasty techniques on nasal tip width. In the clinical routine, nasal tip width and soft-tissue cover thickness are estimated by inspection and palpation rather than by measurement. In this study, a B-mode sonograph with a 12-MHz transducer was used in a noncontact mode to measure tip width 0.5 cm occipital to the tip defining point, distance between the alar cartilage domes, and thickness of the soft-tissue cover overlying the lower lateral cartilages. These parameters were measured 3 to 8 weeks before and 56 days to 19 months after a transdomal suture tip plasty in 18 patients. The distance between the alar cartilage domes seemed to be an important factor for tip width because interdomal distance, not soft-tissue cover thickness, correlated with tip width before surgery (correlation: 0.53). Conversely, the degree of tip refinement correlated with preoperative soft-tissue cover thickness (correlation: 0.75), but not with interdomal distance. Ultrasonic imaging of nasal soft tissues may help to assess the effect of different tip refining procedures and other soft-tissue changes after rhinoplasty.     

A modified Goldman nasal tip procedure for the drooping nasal tip

A modification of Irving Goldman's nasal tip procedure that borrows from the lateral crus to augment the height of the medial crus is described. Goldman's procedure has been modified by not including the vestibular skin with the segment of the lateral crus that is rolled medially to increase nasal tip projection, by adding a nasal septal cartilage strut between the medial crura for support when the medial crura are weak, and by maintaining a small separation caudally of the repositioned lateral crura at the new nasal dome to simulate a double nasal dome. This modified Goldman nasal tip procedure allows the surgeon to reshape the lower lateral nasal cartilage to increase nasal tip projection as an alternative to the use of a shield-type nasal tip graft, and at the same time it narrows the nasal tip with minimal resection of the lateral crus of the lower lateral nasal cartilage.     

Hyphal tip growth inPhytophthora

Germinating cysts and isolated walls from germinating cysts incorporated¹⁴C-UDPG into wall material of which 22.5 and 15% respectively were insoluble in boiling 1 N HCl, indicating that part of the synthetase activity is located in the wall itself. A combination of Urografin and Ficol density gradients was used to separate various intracellular fractions. A consistent separation of -glucanase and UDPG-transferase enriched fractions was achieved. The -glucanase fraction contained dictyosome vesicles and fragments along with some plasma membranes. The UDPG-transferase fraction was relatively rich in membranes resembling rough and smooth ER. The results suggest the two enzymes are transported to the wall by different intracellular routes, and two types of vesicle may be involved. Alkaline phosphatase, -glucosidase and acid phosphatase were found extracellularly and their distribution in density gradients determined. The results of histochemical staining for acid phosphatase, alkaline phosphatase and polysaccharide are described and compared with the biochemical data. -1,3-glucanase, found intra- and extracellularly, induced distorted growth of germ tubes and also removed most of the apical wall when added to the incubation medium. None of these responses were observed with cellulase. Determinations of the osmotic pressure of germinating cysts and incubation medium revealed that the turgor of germinating cysts amounts to about 1.8 at under the conditions used.     

Hyphal tip organization inAllomyces arbuscula

Summary Light and electron microscopic observations on vegetative hyphae ofAllomyces arbuscula revealed the specialized organization of the tip. There were some minor differences related to culture conditions, but the main ultrastructural features common to all hyphal tips disclosed a special type of organization distinct from that of other fungi. A crescent-shaped apical zone consisted of vesicles and membrane cisternae embedded in a granular matrix. Vesicles fused with the apical plasmalemma and presumably contributed to its expansion and to wall growth. The apical zone contained few ribosomes and generally no other organelles. Mitochondria were concentrated in the immediate subapical zone and scattered through the remainder of the hyphae, as were microbodies. Microtubules formed an asterlike structure with its center in the apical zone. Proximally of the apex, microtubules were axially oriented. Nuclei occurred only a certain distance from the tip. The elements of the apex may maintain the polarity of the hyphae via a gradient and hold it in a state of vegetative growth.     

Signaling tip growth in plants

Tip growth is an extreme form of polar growth modulated by both intrinsic and extrinsic spatial cues. Pollen tubes and root hairs have been used as model systems to investigate tip growth signaling in higher plants. Recent studies have focused on tip-localized Ca2+ gradients and Rho GTPases in pollen tubes and a series of mutants affecting root hair tip growth. These molecular and genetic markers will serve as stepping stones towards uncovering tip growth pathways in plants.     

松树梢果蛾类害虫研究进展

松树梢果蛾类是松林和松树种子园的重要害虫。本文综述了这类害虫的种类、寄主范围与分布、发生危害特点、天敌资源等方面的研究进展,并对进一步研究提出展望。     

Microtubules guide root hair tip growth

The ability to establish cell polarity is crucial to form and function of an individual cell. Polarity underlies critical processes during cell development, such as cell growth, cell division, cell differentiation and cell signalling. Interphase cytoplasmic microtubules in tip-growing fission yeast cells have been shown to play a particularly important role in regulating cell polarity. By placing proteins that serve as spatial cues in the cell cortex of the expanding tip, microtubules determine the site where exocytosis, and therefore growth, takes place. Transport and the targeting of exocytotic vesicles to the very tip depend on the actin cytoskeleton. Recently, endoplasmic microtubules have been identified in tip-growing root hairs, which are an experimental system for plant cell growth. Here, we review the data that demonstrate involvement of microtubules in hair elongation and polarity of the model plants Medicago truncatula and Arabidopsis thaliana. Differences and similarities between the microtubule organization and function in these two species are discussed and we compare the observations in root hairs with the microtubule-based polarity mechanism in fission yeast.     

甘蔗茎尖原生分生组织区域化

甘蔗茎尖原生分生组织是甘蔗地上部分一切形态组织的发源中心,通过对6个不同茎径甘蔗品种4个不同营养发育时期的茎尖原生分生组织显微和超微结构观察研究发现:甘蔗茎尖原生分生组织呈半卵型结构,明显分为原套原始细胞区、原体原始细胞区、周缘分生细胞区、髓分生区,其区域化符合原套-原体学说。原套原始细胞区为最外一层细胞,原套细胞之间胞间连丝丰富,而原套与原体细胞之间胞间连丝极少,细胞以垂周分裂为主,扩大原生分生组织表面积;原体位于原套下的分生组织的中央区域,细胞可以进行各个方向的分裂,不断增加体积,原体原始细胞区呈一个球体;周缘分生区位于原套、原体下方两侧,细胞活跃产生叶原基和原形成层细胞;髓分生区细胞位于原体下方周缘分生区内侧,细胞横向分裂纵向排列,使甘蔗茎伸长。     

Calcium and tip growth inNeurospora crassa

Summary We examined the ionic regulation of tip growth inNeurospora crassa by a combination of electrophysiology and confocal microscopy. To determine if transmembrane ionic fluxes are required for tip growth, we voltage clamped the membrane from –200 to +50 mV. In this voltage range, transmembrane ionic fluxes would either reverse (e.g., K⁺) or change dramatically (e.g., Ca²⁺ influx) but had no effect on hyphal growth rates. Therefore, ionic fluxes (including Ca²⁺ influx) may not be required for tip growth. However, intracellular Ca²⁺ may still play an obligatory role in tip growth. To assess this possibility, we first increased cytosolic Ca²⁺ directly by ionophoresis. Elevated Ca²⁺ induced subapical branch initiation, often multiple tips. At hyphal tips, fluorescence ratio imaging using fluo-3 and fura-red revealed a pronounced tip-high Ca²⁺ gradient within 10 m of the tip in growing hyphae which was not observed in nongrowing hyphae. Injection of the Ca²⁺ chelator 1,2-bis(ortho-aminophenoxy)ethane-N,N,N,N-tetrapotassium acetate consistently inhibited growth concomitantly with a depletion of intracellular Ca²⁺ and dissipation of the tip-high gradient. We conclude that Ca²⁺ plays a regulatory role in tip initiation and the maintenance of tip growth. Because plasma membrane ionic fluxes do not play a role in tip growth, we suggest that the tip-high Ca²⁺ gradient is generated from intracellular Ca²⁺ stores in the ascomyceteN. crassa.Abbreviations BAPTA 1,2-bis(ortho-aminophenoxy)ethane-N,N,N,N-tetrapotassium acetate - [Ca²⁺]_i intracellular Ca²⁺ concentration - fluo-3 2,7-dichloro-6-hydroxy-3-oxo-9-xanthenyl-4-methyl-2,2-(ethylenedioxy)dianiline-N,N,N,N-tetraacetic acid