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Scanning X-ray microdiffraction is applied to determine the structural variations of cellulose microfibrils among the fiber cells, vessel cells and ray cells of beechwood. A longitudinal section of beechwood was raster scanned with an X-ray microbeam. This allows to collect diffraction patterns from cell walls of distinct cell types. While the diffraction patterns from fiber cells are dominated by the cellulose signal with a longitudinal orientation, the diffraction patterns from ray and vessel cells show transversal fiber alignment, however to a lower degree of orientation. Moreover, the scattering pattern at small angle region of ray and vessel cells become less pronounced than to fiber cells. These results suggest that the crystalline cellulose of fiber cells has a completely different structure at the meso and molecular level when compared to ray and vessel cellulose within beechwood. [ABSTRACT FROM AUTHOR]

Charged multivesicular body protein 4b (CHMP4B) is a core sub‐unit of the endosomal sorting complex required for transport III (ESCRT‐III) machinery that serves myriad remodeling and scission processes of biological membranes. Mutation of the human CHMP4B gene underlies rare forms of early‐onset lens opacities or cataracts, and CHMP4B is required for lens growth and differentiation in mice. Here, we determine the sub‐cellular distribution of CHMP4B in the lens and uncover a novel association with gap junction alpha‐3 protein (GJA3) or connexin 46 (Cx46) and GJA8 or Cx50. Immunofluorescence confocal microscopy revealed that CHMP4B localized to cell membranes of elongated fiber cells in the outer cortex of the lens—where large gap junction plaques begin to form—particularly, on the broad faces of these flattened hexagon‐like cells in cross‐section. Dual immunofluorescence imaging showed that CHMP4B co‐localized with gap junction plaques containing Cx46 and/or Cx50. When combined with the in situ proximity ligation assay, immunofluorescence confocal imaging indicated that CHMP4B lay in close physical proximity to Cx46 and Cx50. In Cx46‐knockout (Cx46‐KO) lenses, CHMP4B‐membrane distribution was similar to that of wild‐type, whereas, in Cx50‐KO lenses, CHMP4B localization to fiber cell membranes was lost. Immunoprecipitation and immunoblotting analyses revealed that CHMP4B formed complexes with Cx46 and Cx50 in vitro. Collectively, our data suggest that CHMP4B forms plasma membrane complexes, either directly and/or indirectly, with gap junction proteins Cx46 and Cx50 that are often associated with "ball‐and‐socket" double‐membrane junctions during lens fiber cell differentiation. [ABSTRACT FROM AUTHOR]

Cotton is an important natural fiber crop worldwide. Cotton fiber cell is regarded as an ideal material for studying the growth and development of plant cells. Sphingolipids are important components of biomembrane and bioactive molecules which participate in many processes such as plant growth, development regulation, stimulus sensing, and stress response. However, the functions of sphingolipids in the cotton fiber development are still unclear. In the present study, we identified a cotton ceramide synthase gene, GhCS1, which is predominantly expressed in fiber cell. The GhCS1 is located in the endoplasmic reticulum and has the conserved domains of ceramide synthase. Overexpression of GhCS1 gene inhibited both vegetative and reproductive growth in cotton. Importantly, the fiber cell initiation and elongation were severely inhibited when compared with control. Comparison of the sphingolipid profile in the 0-DPA (days past anthesis) ovule (with fiber cell) between control and transgenic cotton plants showed that the content of sphingosines (Sph) decreased significantly in transgenic ovules, whereas the content of phyto-sphingosines (Phyto-Sph) had no change. Meanwhile, the content of ceramide containing Sph and very-long-chain fatty acid (VLCFA) increased significantly in transgenic ovules, while ceramide containing Phyto-Sph and long-chain fatty acids (LCFA)/VLCFA significantly decreased. These results indicated that GhCS1 was a functional ceramide synthase, which preferentially used Sph and VLCFA as substrates and was different from the Arabidopsis ceramide synthase AtLOH1/AtLOH3, which preferentially used Phyto-Sph and VLCFA as substrates, and also different from AtLOH2, which preferentially used Sph and LCFA as substrates. It is suggested that GhCS1 might be a new ceramide synthase gene in the plant, play some roles in the development of fiber cells and cotton plants. [ABSTRACT FROM AUTHOR]

The etiology of age-related cortical cataracts is not well understood but is speculated to be related to alterations in cell adhesion and/or the changing mechanical stresses occurring in the lens with time. The role of cell adhesion in maintaining lens transparency with age is difficult to assess because of the developmental and physiological roles that well-characterized adhesion proteins have in the lens. This report demonstrates that Arvcf, a member of the p120-catenin subfamily of catenins that bind to the juxtamembrane domain of cadherins, is an essential fiber cell protein that preserves lens transparency with age in mice. No major developmental defects are observed in the absence of Arvcf, however, cortical cataracts emerge in all animals examined older than 6-months of age. While opacities are not obvious in young animals, histological anomalies are observed in lenses at 4-weeks that include fiber cell separations, regions of hexagonal lattice disorganization, and absence of immunolabeled membranes. Compression analysis of whole lenses also revealed that Arvcf is required for their normal biomechanical properties. Immunofluorescent labeling of control and Arvcf-deficient lens fiber cells revealed a reduction in membrane localization of N-cadherin, β-catenin, and αN-catenin. Furthermore, super-resolution imaging demonstrated that the reduction in protein membrane localization is correlated with smaller cadherin nanoclusters. Additional characterization of lens fiber cell morphology with electron microscopy and high resolution fluorescent imaging also showed that the cellular protrusions of fiber cells are abnormally elongated with a reduction and disorganization of cadherin complex protein localization. Together, these data demonstrate that Arvcf is required to maintain transparency with age by mediating the stability of the N-cadherin protein complex in adherens junctions.

Stable culm variants are valuable and important material for the study of culm development in bamboo plants. However, to date, there are few reports on the mechanism of variation of these bamboo variants. Phyllostachys nidularia f. farcta (Shidu bamboo) is a bamboo variant with stable phenotypes such as a dwarf culm with a thickened wall. In this study, we systematically investigated the cytological characteristics and underlying mechanism of morphological variation in culms of this variant using anatomical, mathematical statistical, physiological, and genomic methods. The anatomical observation and statistical results showed that the lateral increase of ground tissue in the inner layer of culm wall and the enlargement of vascular bundles are the anatomical essence of the wall thickening of Shidu bamboo; the limited elongation of fiber cells and the decrease in the number of parenchyma cells longitudinally are probably the main causes of the shortening of its internodes. A number of genes involved in the gibberellin synthesis pathway and in the synthesis of cell wall components are differentially expressed between the variant and its prototype, Ph. nidularia , and may play an important role in determining the phenotype of internode shortening in Shidu bamboo. The decrease in gibberellin content and the content of the major chemical components of the cell wall of Shidu bamboo confirmed the results of the above transcriptome. In addition, the variation in culm morphology in Shidu bamboo had little effect on the volume of the culm wall of individual internodes, suggesting that the decrease in the total number of internodes and the decrease in dry matter content (lignin, cellulose, etc.) may be the main factor for the sharp decline in culm biomass of Shidu bamboo. [ABSTRACT FROM AUTHOR]

Stable culm variants are valuable and important material for the study of culm development in bamboo plants. However, to date, there are few reports on the mechanism of variation of these bamboo variants. Phyllostachys nidularia f. farcta (Shidu bamboo) is a bamboo variant with stable phenotypes such as a dwarf culm with a thickened wall. In this study, we systematically investigated the cytological characteristics and underlying mechanism of morphological variation in culms of this variant using anatomical, mathematical statistical, physiological, and genomic methods. The anatomical observation and statistical results showed that the lateral increase of ground tissue in the inner layer of culm wall and the enlargement of vascular bundles are the anatomical essence of the wall thickening of Shidu bamboo; the limited elongation of fiber cells and the decrease in the number of parenchyma cells longitudinally are probably the main causes of the shortening of its internodes. A number of genes involved in the gibberellin synthesis pathway and in the synthesis of cell wall components are differentially expressed between the variant and its prototype, Ph. nidularia, and may play an important role in determining the phenotype of internode shortening in Shidu bamboo. The decrease in gibberellin content and the content of the major chemical components of the cell wall of Shidu bamboo confirmed the results of the above transcriptome. In addition, the variation in culm morphology in Shidu bamboo had little effect on the volume of the culm wall of individual internodes, suggesting that the decrease in the total number of internodes and the decrease in dry matter content (lignin, cellulose, etc.) may be the main factor for the sharp decline in culm biomass of Shidu bamboo.

Sphingolipids serve as essential components of biomembrane and possess significant bioactive properties. Sphingosine-1-phophate (S1P) plays a key role in plant resistance to stress, but its specific impact on plant growth and development remains to be fully elucidated. Cotton fiber cells are an ideal material for investigating the growth and maturation of plant cells. In this study, we examined the content and composition of sphingosine (Sph) and S1P throughout the progression of fiber cell development. The content of S1P elevated gradually during fiber elongation but declined during the transition stage. Exogenous application of S1P promoted fiber elongation while using of FTY720 (an antagonist of S1P), and DMS (an inhibitor of LCBK) hindered fiber elongation. Cotton Long Chain Base Kinase 1 (GhLCBK1) was notably expressed during the fiber elongation stage, containing all conserved domains of LCBK protein and localized in the endoplasmic reticulum. Overexpression GhLCBK1 increased the S1P content and promoted fiber elongation while retarded secondary cell wall (SCW) deposition. Conversely, downregulation of GhLCBK1 reduced the S1P levels, and suppressed fiber elongation, and accelerated SCW deposition. Transcriptome analysis revealed that upregulating GhLCBK1 or applying S1P induced the expression of GhEXPANSIN and auxin related genes. Furthermore, the levels of IAA were elevated and reduced in the fibers when up-regulating or down-regulating GhLCBK1 , respectively. Our investigation demonstrated that GhLCBK1 and its product S1P facilitated the elongation of fiber cells by affecting auxin biosynthesis. This study contributes novel insights into the intricate regulatory pathways involved in fiber cell elongation, identifying GhLCBK1 as a potential target gene and laying the groundwork for enhancing fiber quality via genetic manipulation. [ABSTRACT FROM AUTHOR]

The eye lens is responsible for fine focusing of light onto the retina, and its function relies on tissue transparency and biomechanical properties. Recent studies have demonstrated the importance of Eph-ephrin signaling for the maintenance of life-long lens homeostasis. The binding of Eph receptor tyrosine kinases to ephrin ligands leads to a bidirectional signaling pathway that controls many cellular processes. In particular, dysfunction of the receptor EphA2 or the ligand ephrin-A5 lead to a variety of congenital and age-related cataracts, defined as any opacity in the lens, in human patients. In addition, a wealth of animal studies reveal the unique and overlapping functions of EphA2 and ephrin-A5 in lens cell shape, cell organization and patterning, and overall tissue optical and biomechanical properties. Significant differences in lens phenotypes of mouse models with disrupted EphA2 or ephrin-A5 signaling indicate that genetic modifiers likely affect cataract phenotypes and progression, suggesting a possible reason for the variability of human cataracts due to Eph-ephrin dysfunction. This review summarizes the roles of EphA2 and ephrin-A5 in the lens and suggests future avenues of study.

Arabidopsis thaliana transcription factors belonging to the ERFIIId and ERFIIIe subclade (ERFIIId/e) of the APETALA 2/ethylene response factor (AP2/ERF) family enhance primary cell wall (PCW) formation. These transcription factors activate expression of genes encoding PCW-type cellulose synthase (CESA) subunits and other genes for PCW biosynthesis. In this study, we show that fiber-specific expression of ERF035-VP16 and ERF041-VP16, which are VP16-fused proteins of ERFIIId/e members, promote cell wall thickening in a wild-type background with a concomitant increase of alcohol insoluble residues (cell wall content) per fresh weight (FW) and monosaccharides related to the PCW without affecting plant growth. Furthermore, in the ERF041-VP16 lines, the total amount of lignin and the syringyl (S)/guaiacyl (G) ratio decreased, and the enzymatic saccharification yield of glucose from cellulose per fresh weight improved. In these lines, PCW-type CESA genes were upregulated and ferulate 5-hydropxylase1 (F5H1), which is necessary for production of the S unit lignin, was downregulated. In addition, various changes in the expression levels of transcription factors regulating secondary cell wall (SCW) formation were observed. In conclusion, fiber cell-specific ERF041-VP16 improves biomass yield, increases PCW components, and alters lignin composition and deposition and may be suitable for use in future molecular breeding programs of biomass crops.

Arabidopsis thaliana transcription factors belonging to the ERFIIId and ERFIIIe subclade (ERFIIId/e) of the APETALA 2/ethylene response factor (AP2/ERF) family enhance primary cell wall (PCW) formation. These transcription factors activate expression of genes encoding PCW-type cellulose synthase (CESA) subunits and other genes for PCW biosynthesis. In this study, we show that fiber-specific expression of ERF035-VP16 and ERF041-VP16, which are VP16-fused proteins of ERFIIId/e members, promote cell wall thickening in a wild-type background with a concomitant increase of alcohol insoluble residues (cell wall content) per fresh weight (FW) and monosaccharides related to the PCW without affecting plant growth. Furthermore, in the ERF041-VP16 lines, the total amount of lignin and the syringyl (S)/guaiacyl (G) ratio decreased, and the enzymatic saccharification yield of glucose from cellulose per fresh weight improved. In these lines, PCW-type CESA genes were upregulated and ferulate 5-hydropxylase1 (F5H1), which is necessary for production of the S unit lignin, was downregulated. In addition, various changes in the expression levels of transcription factors regulating secondary cell wall (SCW) formation were observed. In conclusion, fiber cell-specific ERF041-VP16 improves biomass yield, increases PCW components, and alters lignin composition and deposition and may be suitable for use in future molecular breeding programs of biomass crops. [ABSTRACT FROM AUTHOR]

Lignin is a main component of the secondary cell wall in vessels and fibers of xylem tissue. However, the significance of lignin in cell physiology during plant growth is unclear. In this study, we generated lignin-modified Populus via cell-specific downregulation of the 4-coumarate-CoA ligase gene (4CL). The transgenic plants with selective lignin modification in vessel elements or fiber cells allowed us to investigate how lignin affects the physiology of vessel or fiber cells in relation to plant growth. Results showed that vessel-specific suppression of lignin biosynthesis resulted in deformed vessels and normal fibers, while fiber-specific suppression of lignin biosynthesis led to less-lignified fibers and normal vessels. Further analyses revealed that the efficiency of long distance water transport was severely affected in transgenics with vessel-specific lignin modification, while minimal effect was detected in transgenics with fiber-specific lignin modification. Vessel-specific lignin reduction led to high susceptibility to drought stress and poor growth in field, likely due to vessel defects in long distance transport of water. The distinct physiological significance of lignin in different cell types provides insights into the selective modification of lignin for improvement of lignocellulosic biomass utilization.

Lignin is a main component of the secondary cell wall in vessels and fibers of xylem tissue. However, the significance of lignin in cell physiology during plant growth is unclear. In this study, we generated lignin-modified Populus via cell-specific downregulation of the 4-coumarate-CoA ligase gene (4CL). The transgenic plants with selective lignin modification in vessel elements or fiber cells allowed us to investigate how lignin affects the physiology of vessel or fiber cells in relation to plant growth. Results showed that vessel-specific suppression of lignin biosynthesis resulted in deformed vessels and normal fibers, while fiber-specific suppression of lignin biosynthesis led to less-lignified fibers and normal vessels. Further analyses revealed that the efficiency of long distance water transport was severely affected in transgenics with vessel-specific lignin modification, while minimal effect was detected in transgenics with fiber-specific lignin modification. Vessel-specific lignin reduction led to high susceptibility to drought stress and poor growth in field, likely due to vessel defects in long distance transport of water. The distinct physiological significance of lignin in different cell types provides insights into the selective modification of lignin for improvement of lignocellulosic biomass utilization. [ABSTRACT FROM AUTHOR]

Cotton fiber is a seed trichome that protrudes from the outer epidermis of cotton ovule on the day of anthesis (0 day past anthesis, 0 DPA). The initial number and timing of fiber cells are closely related to fiber yield and quality. However, the mechanism underlying fiber initiation is still unclear. Here, we detected and compared the contents and compositions of sphingolipids and sterols in 0 DPA ovules of Xuzhou142 lintless-fuzzless mutants (Xufl) and Xinxiangxiaoji lintless-fuzzless mutants (Xinfl) and upland cotton wild-type Xuzhou142 (XuFL). Nine classes of sphingolipids and sixty-six sphingolipid molecular species were detected in wild-type and mutants. Compared with the wild type, the contents of Sphingosine-1-phosphate (S1P), Sphingosine (Sph), Glucosylceramide (GluCer), and Glycosyl-inositol-phospho-ceramides (GIPC) were decreased in the mutants, while the contents of Ceramide (Cer) were increased. Detail, the contents of two Cer molecular species, d18:1/22:0 and d18:1/24:0, and two Phyto-Cer molecular species, t18:0/22:0 and t18:0/h22:1 were significantly increased, while the contents of all GluCer and GIPC molecular species were decreased. Consistent with this result, the expression levels of seven genes involved in GluCer and GIPC synthesis were decreased in the mutants. Furthermore, exogenous application of a specific inhibitor of GluCer synthase, PDMP (1-phenyl-2-decanoylamino-3-morpholino-1-propanol), in ovule culture system, significantly inhibited the initiation of cotton fiber cells. In addition, five sterols and four sterol esters were detected in wild-type and mutant ovules. Compared with the wild type, the contents of total sterol were not significantly changed. While the contents of stigmasterol and campesterol were significantly increased, the contents of cholesterol were significantly decreased, and the contents of total sterol esters were significantly increased. In particular, the contents of campesterol esters and stigmasterol esters increased significantly in the two mutants. Consistently, the expression levels of some sterol synthase genes and sterol ester synthase genes were also changed in the two mutants. These results suggested that sphingolipids and sterols might have some roles in the initiation of fiber cells. Our results provided a novel insight into the regulatory mechanism of fiber cell initiation.

As a class of important cell growth regulators, expansins have been studied for over 20 years. Since Neolamarckia cadamba (Roxb.) Bosser was praised as a ‘miraculous tree’ at the World Forestry Congress in 1972 due to its rapid growth. A lot of research has been carried out to uncover the underlying mechanisms of this rapid growth. Based on previous findings and our research, we hypothesized that expansins may play an important role in such growth. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the N. cadamba expansin family member NcEXPA8 is highly expressed in all four young tissues, particularly in the cambium region, suggesting that NcEXPA8 acts as a key regulator of secondary growth in this gene family. Overexpression of NcEXPA8 in Arabidopsis thaliana increased the diameter and height of the main stem. It also promoted interfascicular fiber cell elongation and cell-wall thickness but did not alter the cellulose content in the cell wall. These results suggested that expansins act as activators during secondary fiber cell elongation during tip growth to promote plant growth.

Cotton fiber is a single-celled seed trichrome that arises from the epidermis of the ovule’s outer integument. The fiber cell displays high polar expansion and thickens but not is disrupted by cell division. Therefore, it is an ideal model for studying the growth and development of plant cells. Sphingolipids are important components of membranes and are also active molecules in cells. However, the sphingolipid profile during fiber growth and the differences in sphingolipid metabolism at different developmental stages are still unclear. In this study, we detected that there were 6 classes and 95 molecular species of sphingolipids in cotton fibers by ultrahigh performance liquid chromatography-MS/MS (UHPLC-MS/MS). Among these, the phytoceramides (PhytoCer) contained the most molecular species, and the PhytoCer content was highest, while that of sphingosine-1-phosphate (S1P) was the lowest. The content of PhytoCer, phytoceramides with hydroxylated fatty acyls (PhytoCer-OHFA), phyto-glucosylceramides (Phyto-GluCer), and glycosyl-inositol-phospho-ceramides (GIPC) was higher than that of other classes in fiber cells. With the development of fiber cells, phytosphingosine-1-phosphate (t-S1P) and PhytoCer changed greatly. The sphingolipid molecular species Ceramide (Cer) d18:1/26:1, PhytoCer t18:1/26:0, PhytoCer t18:0/26:0, PhytoCer t18:1/h20:0, PhytoCer t18:1/h26:0, PhytoCer t18:0/h26:0, and GIPC t18:0/h16:0 were significantly enriched in 10-DPA fiber cells while Cer d18:1/20:0, Cer d18:1/22:0, and GIPC t18:0/h18:0 were significantly enriched in 20-DPA fiber cells, indicating that unsaturated PhytoCer containing hydroxylated and saturated very long chain fatty acids (VLCFA) play some role in fiber cell elongation. Consistent with the content analysis results, the related genes involved in long chain base (LCB) hydroxylation and unsaturation as well as VLCFA synthesis and hydroxylation were highly expressed in rapidly elongating fiber cells. Furthermore, the exogenous application of a potent inhibitor of serine palmitoyltransferase, myriocin, severely blocked fiber cell elongation, and the exogenous application of sphingosine antagonized the inhibition of myriocin for fiber elongation. Taking these points together, we concluded that sphingolipids play crucial roles in fiber cell elongation and SCW deposition. This provides a new perspective for further studies on the regulatory mechanism of the growth and development of cotton fiber cells.

Producing nanocellulose from lignocellulosic plants is difficult but can be achieved with microwave-assisted treatment. However, the changes in dimensions during the process have not been investigated thoroughly. In this study, kenaf bast was used to produce cellulose nanofibers using microwave, chemical, and ultrasonic treatments. Fiber sizes were monitored throughout the experiment using an optical microscope and scanning electron microscopy (SEM). The kenaf single fiber cells were also isolated and measured. The results showed that the duration of microwave treatment notably influenced the destruction of kenaf fibers, and the concentration of NaOH in the chemical treatment had only a limited effect on the reduction of kenaf particle size. Both the microwave and chemical treatments were able to destruct the kenaf fibers longitudinally, and the ultrasonic treatment was able to reduce cellulose particles from micro-size to nano-size. [ABSTRACT FROM AUTHOR]

As a class of important cell growth regulators, expansins have been studied for over 20 years. SinceNeolamarckia cadamba(Roxb.) Bosser was praised as a ‘miraculous tree’ at the World Forestry Congress in 1972 due to its rapid growth. A lot of research has been carried out to uncover the underlying mechanisms of this rapid growth. Based on previous findings and our research, we hypothesized that expansins may play an important role in such growth. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that theN. cadambaexpansin family memberNcEXPA8is highly expressed in all four young tissues, particularly in the cambium region, suggesting thatNcEXPA8acts as a key regulator of secondary growth in this gene family. Overexpression ofNcEXPA8inArabidopsis thalianaincreased the diameter and height of the main stem. It also promoted interfascicular fiber cell elongation and cell-wall thickness but did not alter the cellulose content in the cell wall. These results suggested that expansins act as activators during secondary fiber cell elongation during tip growth to promote plant growth. [ABSTRACT FROM PUBLISHER]

The quality of cut Paeonia lactiflora flowers is limited by their low stem mechanical strength, but the underlying mechanism of this low strength is poorly understood. In this study, two P. lactiflora cultivars with distinct stem mechanical strengths (Chui Touhong with low stem mechanical strength and Da Fugui with high stem mechanical strength) were used as test materials. The xylem development was examined at the cellular level, and the phloem conductivity was analyzed by evaluating phloem geometry. The results showed that the secondary cell wall formation of the xylem of Chui Touhong was affected primarily in fiber cells but was affected little in vessel cells. The formation of the secondary cell walls in the xylem fiber cells of Chui Touhong was delayed, resulting in longer and thinner fiber cells with a lack of cellulose and S-lignin in the secondary cell walls. Moreover, the phloem conductivity of Chui Touhong was lower than that of Da Fugui, and more callose was accumulated in the lateral walls of the phloem sieve elements of Chui Touhong. Consequently, the delayed deposition of the secondary cell walls of the xylem fiber cells was the main factor leading to the low stem mechanical strength of Chui Touhong, and the low stem mechanical strength was closely related to the low conductivity of sieve tubes and extensive callose accumulation in the phloem. These findings provide a new perspective on enhancing P. lactiflora stem mechanical strength by targeting single cell level, and lay the foundation for future works on the correlation between phloem long-distance transport and stem mechanical strength. • The formation of secondary cell walls exhibited cell type specific in fiber and vessel cells. • The delayed deposition of secondary cell walls changed fiber cell morphology. • The longer and thinner fiber cells led to low stem mechanical strength. • The phloem conductivity depended on sieve tube geometry. • The low conductivity and extensive callose accumulation in relation to low stem mechanical strength. [ABSTRACT FROM AUTHOR]

Three flax (Linum usitatissimum L.) cultivars ('Ariane', 'Argos' and 'Viking') were used to study the effect of diurnal temperature range (DIF) applied throughout the whole growth stage on the development of fiber cells. Diurnal temperature ranges were set at 5°C, 10°C and 15°C with the same daily mean temperature and accumulated growing degree days (GDDa). All measured traits showed obvious DIF and varietal differences except the length of fiber bundle (LFB) and the inter-fiber bundle distance (IFBD). Significant interactions of DIF and cultivar were observed to affect the width of fiber bundle (WFB), the size of fiber cell (SFC), the size of fiber cell cavity (SFCC) and the thickness of fiber cell wall (TFCW). Compared with other DIFs, the number of fiber cells per bundle (NFCB) and WFB increased, but IFBD decreased under DIF 5. However, WFB, TFCW and NFCB all decreased under DIF 10. Under DIF 15 condition, both SFC and SFCC increased. For 'Ariane', IFBD was short under DIF 5, but SFC and SFCC were both large under DIF 10. For 'Argos', IFBD was also short under DIF 5. Under DIF 10, WFB, SFC and TFCW were all small, but IFBD was long. For 'Viking', TFCW was small under DIF 10 but large under DIF 15. All these results suggested a definite influence of DIF on the development of fiber cells in flax, and DIF set at 5°C benefited the number of fiber cells in a bundle but DIF 15 was optimal for the size of fiber cells. [ABSTRACT FROM AUTHOR]

The eye lens is a transparent and avascular organ in the front of the eye that is responsible for focusing light onto the retina in order to transmit a clear image. A monolayer of epithelial cells covers the anterior hemisphere of the lens, and the bulk of the lens is made up of elongated and differentiated fiber cells. Lens fiber cells are very long and thin cells that are supported by sophisticated cytoskeletal networks, including actin filaments at cell junctions and the spectrin–actin network of the membrane skeleton. In this review, we highlight the proteins that regulate diverse actin filament networks in the lens and discuss how these actin cytoskeletal structures assemble and function in epithelial and fiber cells. We then discuss methods that have been used to study actin in the lens and unanswered questions that can be addressed with novel techniques. [ABSTRACT FROM AUTHOR]