Novel Pectin/Chia-Mucilage Membranes:Human Serum Albumin Adsorption,Biocompatibility,and Physical-Chemical Properties

This study aimed to characterize the physical-chemical and biological properties of pectin(PC)/chia seed mucilage(CM)membranes.PC/CM[100/0(control),80/20%,60/40%,and 40/60%w/w]membranes were prepared using the casting method.The membranes(PC/CM)were thin,yellow,lightly opaque(≈10%)and capable of blocking light UVB(between 66 at 52%).SEM analysis showed the presence of aggregates in the shape of a sphere(≈13μm)and ovoid(≈25μm).The proportion of 80/20 showed an increase in tensile strength(29%)and elastic modulus(19%)when compared to the control.FTIR analysis exhibited intermolecular interactions between PCPC,PC-CM,and CM-CM in the membranes.The thermal analysis(600°C)showed a slight improvement in the percentage of residual mass-loss of 3.31%(80/20)that control.The 40/60 membrane showed the lowest percentage of hemolysis(2.94%)but limited human albumin adsorption capacity.These results suggested that the blend PC/CM may be considered as a biomaterial for medical applications.

Achene mucilage formation process and extrusion from hydrated pericarp of Mirabilis himalaica

Myxospermy is an important feature of achenes of the alpine plant Mirabilis himalaica,and the achene mucilage increases the germination rate and early seedling growth during exposure to abiotic stresses,which has important functions that allow M.himalaica to survive the extreme climate of the Tibet Plateau.However,achene formation and mucilage extrusion are poorly understood.In the present study,comprehensive analyses were performed on mucilage production during achene development and mucilage release from hydrated achene pericarp in M.himalaica.First,fertilization initiated the development of M.himalaica achenes,during which their color,size and texture were altered dramatically.Second,using a metachromatic staining procedure,cytological events,the establishment of mucilage secretory cells in the inner epicarp layer were observed.The hydration of mature achenes led to the rapid bursting of mucilage secretory cells,which released a hydrophilic gel that surrounded the achenes.Finally,enzymatic digestion indicated that major components of the mucilage were pectins;glucose(41.40%),rhamnose(26.58%),galactose(18.33%),trehalose(12.12%),and mannose(1.57%)were found to be the components of achene by using ion-exchange chromatography.

Wound healing potential of Althaea officinalis flower mucilage in rabbit full thickness wounds

Objective: To evaluate and practically demonstrate the in fluence of Althaea officinalis flower mucilage as a plant known in Iran's and other Middle Eastern countries' traditional medicine for its wound healing properties.Methods: Animals were divided into 6 groups of 5 cases including a non-treated group as the negative control group receiving no treatment, a group treated with eucerin as the positive control group, a phenytoin 1% group as a standard group treated topically with phenytoin 1% hand-made ointment, and treatment groups treated with hand-made Althaea officinalis flower mucilage(AFM) ointment in a eucerin base with different concentrations(5%, 10%, 15%).Results: Among the treatment groups, the AFM 15% ointment showed the best result.Wound healing duration was reduced by the surface application of these groups. Wound closure was completed on Days 14 and 15 in the AFM 15% ointment and phenytoin 1%groups, respectively. No significant difference was observed in healing period between these groups.Conclusions: In conclusion, AFM 15% ointment was found to reduce wound healing time without any significant difference with the phenytoin 1% ointment. The authors suggest increased AFM effectiveness in when combined with phenytoin or other effectual plants.

Identification of Mucilage Cavity as a Significant Microscopic Characteristic Existing in Phloem Instead of Pith of Radix et Rhizoma Rhei

The morphologic and microscopic features of Radix et Rhizoma Rhei were studied. The study verified that the mucilage cavities did exist in phloem of rhizomes and roots or abnormal vascular bundles. Also, they were in similar distribution in three species of Radix et Rhizoma Rhei. The diagnostic characteristic for microscopic identification was found to be the similar distribution of abnormal vascular bundles in pith of rhizomes in all three species. And the appearance of the crude drug varied more depending on the plants＇ geographical origin and different preliminary treatment on the spot of collection than on the species differences. Our findings, having not been delineated clearly so far in the previous reports, are helpful for clarifying current descriptions in different literatures or standards and make a full understanding on microscopic and macroscopic identification of Radix et Rhizoma Rhei.

Comparative Physico-Chemical Characterization of the Mucilages of Two Cactus Pears (<i>Opuntia</i>Spp.) Obtained from Mekelle, Northern Ethiopia

Cactus is a plant that naturally grows in tropical and semi-tropical regions of the world. The composition of this mucilage is believed to differ from species to species. Hence, comparative study was carried out on mucilages of Opuntia ficus-indica (OFI) and Opuntia stricta (OS) as regard to their physico-chemical properties and acute toxicity levels. The study indicated that solubility of the dry mucilages were comparable and increased as raise in temperature. However, at all temperature levels the swelling powers were significantly higher in mucilage of OS than that of OFI. At 100% RH the moisture sorption property of OFI (95.4%) was higher than that of OS (76.9%). The pH values of both mucilages at 12% dispersions were found to be 5.57 and 5.87 for OFI and OS, respectively. The conductivity at the same concentration, 12% (w/v), of OFI was 13.12 mS/cm while that of OS was 9.31 mS/cm. The apparent viscosities at 12% (w/v) were 9,017 mPas and 10,060 mPas for OFI and OS, respectively. The apparent viscosities of the dispersions decreased with increase in shear rates which rendered the dispersions a pseudoplastic flow. The surface tension of the aqueous dispersions of OFI (28.71 mN/M) decreased significantly as compared to that of OS (39.7 mN/M). The results of the study proved that the mucilage of OS was superior to OFI mucilage for use as food and pharmaceutical excipients. Moreover, both mucilages exhibited low acute toxicity levels.

Use of Prosopis laevigata Seed Gum and Opuntia ficus-indica Mucilage for the Treatment of Municipal Wastewaters by Coagulation-Flocculation

Prosopis laevigata and Opuntia ficus-indica grow in arid and semiarid regions of Mexico and other countries. Both produce biopolymers with interesting characteristics from the rheological point of view as well as because of their coagulating-flocculating capabilities. Prosopis produce galactomannans inside the endosperm, very similar to those found in guar, locust bean, and tara gums. Opuntia sp. produces mucilage that contains polygalacturonic acid and five neutral sugars. Prosopis seed gum has not been proposed to be used as coagulant-flocculant before. In the case of Opuntia mucilage, some authors have suggested its use in the treatment of waters, using either the mucilage or the whole cladode powder. The use of these products in the treatment of municipal or even industrial wastewaters could give rise to diverse benefits. From the environmental point of view, treated waters with neither Fe nor Al, nor synthetic polymers would be obtained (with less toxicity risk). Besides, the produced sludges would be smaller in amount, with better biodegradability, and lower metals content. From the economical point of view, the use of these biopolymers would give an added value to the Opuntia and Prosopis culture in Mexico, helping small communities to enhance their incomes by producing environmental-friendly products. This work shows that both Prosopis galactomannan and Opuntia mucilage can be used to treat municipal wastewaters with an initial organic charge of about 827 mg/L as COD by the coagulation-flocculation process, with COD removals for the mesquite seed gum of up to 90% (pH 10, dose of 75 mg/L) and of 60% (pH 7, doses of 50 and 150 mg/L). In the case of mucilage, 65% of the initial COD was removed at pH 10 (dose of 50 mg/L). These figures are very promising for the treatment of wastewaters, with environmental-friendly products.

<i>Opuntia ficus-indica</i>Pruning Waste Recycling: Recovery and Characterization of Mucilage from Cladodes

The present work focuses on the proximate physical and chemical profile of Opuntia ficus-indica mucilage, mechanically extracted from cladodes, a waste of pruning in traditional organic cactus pear orchards in Italy (San Cono, Sicily). The mechanical extraction increased the mucilage yield to 30% dry weight. Physical characterization concerns pH, viscosity, free acidity and density, useful for emulsifying capacity. Spectrophotometric analysis was applied to assess total carbohydrates, proteins, uronic acids, total polyphenols content and antioxidant capacity. DART-MS and SEM-EDX were performed to evaluate functional mucilage components and relative amounts of minerals, respectively. From the main results Opuntia ficus-indica by-product, in addition to the preponderant total carbohydrates content, shows the high concentration in calcium and potassium and a fair amount of health-promoting phytochemicals, which make it a good candidate for the different type of industrial applications.

Enhancing maize's nitrogen-fixing potential through ZmSBT3, a gene suppressing mucilage secretion∞

Maize(Zea mays)requires substantial amounts of nitrogen,posing a challenge for its cultivation.Recent work discovered that some ancient Mexican maize landraces harbored diazotrophic bacteria in mucilage secreted by their aerial roots.To see if this trait is retained in modern maize,we conducted a field study of aerial root mucilage(ARM)in 258 inbred lines.We observed that ARM secretion is common in modern maize,but the amount significantly varies,and only a few lines have retained the nitrogen‐fixing traits found in ancient landraces.The mucilage of the high‐ARM inbred line HN5‐724 had high nitrogen‐fixing enzyme activity and abundant diazotrophic bacteria.Our genome‐wide association study identified 17 candidate genes associated with ARM across three environments.Knockouts of one candidate gene,the subtilase family gene ZmSBT3,confirmed that it negatively regulates ARM secretion.Notably,the ZmSBT3 knockout lines had increased biomass and total nitrogen accumulation under nitrogen‐free culture conditions.High ARM was associated with three ZmSBT3 haplotypes that were gradually lost during maize domestication,being retained in only a few modern inbred lines such as HN5‐724.In summary,our results identify ZmSBT3 as a potential tool for enhancing ARM,and thus nitrogen fixation,in maize.

Regulation of Root-Knot Nematode Behavior by Seed-Coat Mucilage-Derived Attractants

Seed exudates influence the behavior of soil organisms,but howthis occurs remains unclear,particularly for multicellular animals.Here we show that compounds associated with Arabidopsis seed-coat mucilage regulate the behavior of soil-borne animals,specifically root-knot nematodes (RKNs).Infective RKN J2 larvae actively travel toward Arabidopsis seeds through chemotaxis.Analysis of Arabidopsis mucilage mutants demonstrated that the attraction of RKNs toArabidopsis seeds requires the synthesis and extrusion of.seed-coat mucilage.Extracted mucilage alone is not sufficient to attract RKNs,but seed-surface carbohydrates and proteins are required for this process.These findings suggest that the RKN chemoattractant is synthesized de novo upon mucilage extrusion but may be highly unstable.RKNs attracted by thismucilage-dependent mechanism can infect the emerging seedling.However,the attraction signal from seedling roots likely acts independently of the seed-coat signal and may mask the attraction to seed-coat mucilage after germination.Multiple RKN species are attracted byArabidopsis seeds,suggesting that this mechanism is conserved in RKNs.These findings indicate that seed exudate can regulate the behavior of multicellular animals and highlight the potential roles of seed-coat mucilage in biotic interactions with soil microorganisms.

Effects of cowpea(Vigna unguiculata) root mucilage on microbial community response and capacity for phenanthrene remediation

Biodegradation of polycyclic aromatic hydrocarbons（PAHs） is normally limited by their low solubility and poor bioavailability. Prior research suggests that biosurfactants are synthesized as intermediates during the production of mucilage at the root tip. To date the effects of mucilage on PAH degradation and microbial community response have not been directly examined. To address this question, our research compared 3 cowpea breeding lines（Vigna unguiculata） that differed in mucilage production for their effects on phenanthrene（PHE） degradation in soil. The High Performance Liquid Chromatography results indicated that the highest PHE degradation rate was achieved in soils planted with mucilage producing cowpea line C1, inoculated with Bradyrhizobium, leading to 91.6% PHE disappearance in 5 weeks. In root printing tests, strings treated with mucilage and bacteria produced larger clearing zones than those produced on mucilage treated strings with no bacteria or bacteria inoculated strings. Experiments with14C-PHE and purified mucilage in soil slurry confirmed that the root mucilage significantly enhanced PHE mineralization（82.7%）, which is 12% more than the control treatment without mucilage. The profiles of the PHE degraders generated by Denaturing gradient gel electrophoresis suggested that cowpea C1, producing a high amount of root mucilage, selectively enriched the PHE degrading bacteria population in rhizosphere. These findings indicate that root mucilage may play a significant role in enhancing PHE degradation and suggests that differences in mucilage production may be an important criterion for selection of the best plant species for use in phytoremediation of PAH contaminated soils.

Role of mucilage during achene germination and sprout growth of the endangered Tibetan medicinal herb Mirabilis himalaica (Nyctaginaceae) exposed to abiotic stresses

Aim Mirabilis himalaica(Nyctaginaceae)is an endangered medicinal plant mainly distributed in the plateau region of northern Tibet,China.The outer surface of M.himalaica achenes is covered by a pectinaceous mucilaginous layer upon hydration.However,the role of the achene mucilage is poorly understood.in this study,we inves-tigated the effects of mucilage on achene germination and sprout growth under abiotic stress to explain how M.himalaica survive the alpine environment.Methods We investigated the effect of mucilage on achenes germination by contrast the capacity of water absorption,dehydration and respira-tion of intact achene and the achene with mucilage removal.We performed abiotic stresses experiments including drought stress,salt stress,cold stress and high temperature stress,and quantified the effects of mucilage removal on achene germination rate,root and shoot lengths of seedlings.Important Findings Mucilage is extremely hydrophilic,and the mass of intact achenes can be 9-fold greater than that of demucilaged achenes.The removal of the mucilaginous layer did not significantly change final germination percentages under ideal conditions,but intact achenes(i.e.with muci-lage)took longer to germinate.The mucilage significantly decreased seed respiration rates by acting as a physical barrier that prevented oxygen diffusion.Germination rates,shoot and root growth of intact achenes were higher than those of demucilaged ones during exposures to cold,heat,osmotic and salt stresses.Achene mucilage presumably plays an ecologically important role in the life cycle of M.himalaica by aiding the critical achene germination and early seedling growth in the stressful habitats of the plateau region of northern Tibet.

超前服用利多卡因明胶对无痛胃镜检查中丙泊酚复合芬太尼麻醉的影响

目的研究服用利多卡因明胶在无痛胃镜检查中对丙泊酚复合芬太尼麻醉的影响。方法 200例ASA分级为Ⅰ～Ⅱ行无痛胃镜检查患者,随机分为两组。Ⅰ组检查前10min口服利多卡因明胶,行丙泊酚复合芬太尼麻醉;Ⅱ组检查前10min口服10mL生理盐水,行丙泊酚复合芬太尼麻醉。记录丙泊酚用量,镜检时间,苏醒时间,麻醉效果,同时记录检查前(T0),芬太尼注射完毕时(T1),插管入咽喉时(T2),检查中(T3),检查毕(T4),清醒时(T5)时MAP,HR,SpO2的监测值。结果Ⅰ组的丙泊酚用量、苏醒时间均低于Ⅱ组(P<0.05)。T2时,Ⅰ组的MAP、HR显著低于Ⅱ组,Ⅰ组的SpO2显著高于Ⅱ组(P<0.05)。两组患者的镜检时间、麻醉效果无显著差异。结论在无痛胃镜检查中超前服用利多卡因明胶,能有效地减少丙泊酚用量和苏醒时间,保持呼吸循环稳定。

Two new species of Mesozoic tree ferns(Osmundaceae:Osmundacaulis)in Eurasia as evidence of long-term geographic isolation

The fossil trunks and rhizomes of Osmundaceae provide important information about its evolutionary history.Due to limited records of the Mesozoic trunks and rhizomes in the Eurasia of the Northern Hemisphere,our understanding on the fossil diversity of the Osmundaceae is hindered.Two new species of the Osmundaceae trunks,Osmundacaulis asiatica sp.nov.and Osmundacaulis sinica sp.nov.representing the first discovery of the Mesozoic tree fern genus Osmundacaulis in Eurasia,are described from Wudalianchi and Qiqihar,Heilongjiang Province,Northeast China,which enriches the plant diversity of the Osmundaceae in the Eurasia,and provides vital evidence for studying the distribution,radiation and evolution of the genus during the Cretaceous.The fossil records suggest that Osmundacaulis species may have evolved from a common ancestor,which first appeared in the Australian portion of Pangaea,and then spread to ancient northern North America and ancient East Asia.Since then,they developed into different species through their own evolutionary lines.The Chinese species have a special local feature that the outer cortex is thicker than the inner cortex,in contrast with reported Osmundacaulis species having thinner outer cortex and thicker inner cortex.Long-term geographic isolation may have led to the radiation of diverse Osmundacaulis species and the appearance of region-specific features,such as the thick outer cortex and the thin inner cortex of the Chinese species.Among all reported Osmundacaulis species,the two new species found in China,O.nerii from the Jurassic of Australia and the O.lemonii from the Jurassic of the USA,have special groups of mucilage-sacs inside sclerenchyma ring of petiole base.Mucilage sacs probably originated independently among taxonomic groups,representing convergent adaptations to similar habitats,rather than indicating genetic inheritance from a common ancestor.

Pharmacodynamics Study in vitro and in vivo of Zijin Huadu Suppository Treating Cervicitis

[Objectives] To observe the pharmaceutical effect of Zijin Huadu suppository on treatment of cervicitis induced by virus,bacteria and phenol in vivo and in vitro,and provide experimental basis for evaluating its therapeutic effects for cervicitis. [Methods]Real-time RT-PCR and CPE methods were used to observe the inhibition of Zijin Huadu suppository on virus,and turbidimetry was used to observe bacteriostatic action; HE pathological section was used to observe cervicitis of rat,and enzyme-linked immunosorbent assay was used to detect virus' s expression in cervical tissue.[Results]In cervicitis rat model infected by HPV16,Zijin Huadu suppositories at the doses of 1. 2,0. 6 and0. 3 g/( kg·d) had significant inhibitory effect on HPV16 expression in cervical tissues,and the doses of 1. 2 and 0. 6 g/( kg·d) had significantly inhibitory effect on pathological changes of cervical tissues. In cervicities rat models infected mixedly by Escherichia coli,Neisseria gonorrhoeae and Staphylococcus aureus,Zijin Huadu suppositories at the doses of 1. 2 and 0. 6 g/( kg·d) had significant inhibitory effect on pathological changes of cervical tissues. In cervicitis rat models induced by chemical substances,Zijin Huadu suppositories at the dose of1. 2 g/( kg·d) had significant inhibitory effect on vagina and cervix lesions in rats. In vitro,Zijin Huadu suppository showed obvious inhibitory effects on HSV-2,HPV16,Staphylococcus aureus,Staphylococcus albus,Staphylococcus epidermidis,group B Streptococcus,E. coli,Pseudomonas aeruginosa,Proteusbacillus vulgaris,Neisseria gonorrhoeae and Candida albicans.[Conclusions] Zijin Huadu suppository has obvious inhibitory effect in vitro on viruses and bacteria,and could obviously improve the phenol-induced cervicitis.

Assessment of the consecutive harmful dinoflagellate blooms during 2015 in the Izmit Bay(the Marmara Sea)

A series of red tides were observed during 2015 in the Izmit Bay（the Marmara Sea） which is located in the most industrialized and populated region of Turkey. Six samplings were carried out in this area following the red tides.Nitrite-N, nitrate-N, ammonia, silica and orthophosphate concentrations were analyzed spectrophotometrically.Physicochemical conditions were measured by CTD probe. Plankton quantification was performed using counting chambers under microscopes. Prorocentrum micans was the most abundant species, except on May 14,2015, when Noctiluca scintillans was dominant. The abundance of P. micans reached average 18×10~6 ind./L on May 3, 2015 in the Karamürsel station, simultaneously with elevated levels of NH_3 and o-PO_4^（3–）. The sample was also abundant in dead amphipods（（72±12） ind./L） that had been covered by mucilage aggregates produced by P.micans. The highest biomass（calculated by carbon） was recorded as（268±26.0） mg/L on May 14 in the Hereke station. Beside the anthropogenic wastewater discharges, unknown sources and resuspensions caused increases in nutrient levels. After long term northeaster gusts（35 km/h for 5 d） an upwelling occurred on November 6, 2015 after wind-induced sediment resuspension. Although nutrient discharges remarkably decreased over 30 years through established wastewater treatment plants, harmful phytoplankton blooms still occur. Comparing the present results with other studies in nearby Mediterranean seas reveals that the most intense harmful dinoflagellate bloom in recent years occurred in the Izmit Bay. Therefore, additional protection measures necessary for a cleaner Izmit Bay. These incidents also demonstrate that contaminants, accumulated in sediment,may have long-lasting effects on enclosed marine ecosystems.

The environmental adaptability and reproductive properties of invasive green alga Codium fragile from the Nan'ao Island,South China Sea

It has been widely recognized that biological invasion has become one of the greatest threats to the ecosystem.Codium fragile is an invasive species which exhibits a variety of attributes like parthenogenesis,winter fragment,and vegetative reproduction;and therefore,it has become a successful invader,colonizing most subtropical regions.In China’s southeast coastal aquaculture waters,the green algal bloom caused by C.fragile will probably become a serious problem.In order to understand more details about the species,an experiment focused on its reproductive characteristics was conducted using culture established from a sample collected in the aquaculture raft of the Nan’ao Island in the South China Sea.The results showed that there were two types of gametes resembling aplanospores and zoospores respectively,both of which were able to germinate.During the gametes liberation,a long mucilage tube was formed out of the mouth of the gametangium assisting dispersal of gametes away from the parent plant.This tube was adapted not only to its surrounding flowing water environment but also to its parent plant’s outer gelatinous structure.In general,the optimum temperature for gametes release and germination was 15-20℃ and 15℃,respectively,which corresponded to the local offshore marine water.The plant was observed to produce vegetative buds under favourable reproductive conditions which were called propagules.They were capable of developing into filamentous thalli.The results will provide some scientific evidences for revealing the biological mechanism of bloom and control strategies of invasive green algae.

A Five-year Follow-up Study on the Efficacy and Safety of Female Tubal Sterilization by Chemical Instillation

A multi center randomized clinical trial was adopted in the present study. 1705 eligible women with identical demographic and gynecological characteristics were divided into two groups: 871 using phenol atabrine paste (PAP) and 834 using phenol mucilage (PM). The five year follow up rates for the two groups were 97.5% and 98.1%, respectively. The multiple decrement life table analysis showed that there was a significant difference in the gross cumulative failure rates between the two groups. The 60th month gross cumulative failure rates for PAP group and PM group were 4.61% and 11.87%, respectively, thus indicating the efficacy of PAP to be significantly higher than that of PM. 97.7% users had cervical smear examinations, but no suspected cancer cells or cancer cells were found. Meanwhile, there was no known diseases related to the chemical reagent. This follow up study indicates that tubal sterilization by chemical instillation is a simple,safe and efficient female method. It suggested that this method would be introduced to a wider use on the basis of modification in the composition of chemical agents, standardized operational procedure, and improved administrative regulation in the use of this technology.

Identification and Quantification of Monosaccharides in Aloe vera Gel by Acid and Enzymatic Hydrolysis and Wet Heat Treatment

Aloe vera (Aloe barbadensis Miller) possesses curative and therapeutic properties attributed to the polysaccharides found in its tissue. This work aimed to study hydrolyzed (chemical and enzymatical) Aloe vera gel extracts using ultrafiltration membranes with a pore size of 0.22 micron (μm). Nine chemical treatments were achieved with H2SO4 and three wet heat treatments were carried out at a pressure of 1.2 lbf/in2 for 15 minutes;in both cases, three different concentrations of Aloe vera gel juice (AGJ) were used: 1.5%, 2.5% and 3.5% w/w. The concentrations of H2SO4 were 0.10%, 0.25% and 0.40% w/w. Chemical experiments are performed over a factorial 32 design and results were analyzed using SPSS software (version 17, SPSS Inc.), finding the one labeled T7 (15 ml of AGJ 3.5% with 15 ml of H2SO4 0.10% added) the best of them, as it leaded to 0.0446 mg/ml of liberated glucose. Among the three wet heat treatments, the one labeled TC3 (15 ml of AGJ 3.5% with 15 ml of H2O added) was the best-performing one, as it leaded to 0.292 mg/ml of liberated glucose. Furthermore, an enzymatic hydrolysis was carried out using Novozymes’ Pectinex? AR and Viscozyme?. Hydrolisis with both enzymes yield to better results than acid hydrolysis: in the treatment with Pectinex? AR, 3.282 mg/ml of liberated glucose were obtained and 3.302 mg/ml in the treatment with Viscozyme?. The hydrolyzed substances obtained by acid and enzymatic hydrolysis, as well as by wet heat treatment, were subsequently analyzed by thin layer chromatography (TLC), using glucose, galactose and arabinose 1000 ppm solutions as reference patterns. Among the treatments by H2SO4, the one labeled T4 obtained an Rf value of 50, the same as on the galactose reference pattern.

Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa

Galacturonosyltransferase 1 （GAUT1） is an α1,4-D-galacturonosyltransferase that transfers galacturonic acid from uridine 5＇-diphosphogalacturonic acid onto the pectic polysaccharide homogalacturonan （Sterling et al., 2006）. The 25-member Arabidopsis thaliana GAUT1-related gene family encodes 15 GAUT and 10 GAUT-like （GATL） proteins with, respectively, 56-84 and 42-53% amino acid sequence similarity to GAUT1. Previous phylogenetic analyses of AtGAUTs indicated three clades： A through C. A comparative phylogenetic analysis of the Arabidopsis, poplar and rice GAUT families has sub-classified the GAUTs into seven clades： clade A-1 （GAUTs 1 to 3）; A-2 （GAUT4）; A-3 （GAUTs 5 and 6）; A-4 （GAUT7）; B-1 （GAUTs 8 and 9）; B-2 （GAUTs 10 and 11）; and clade C （GAUTs 12 to 15）. The Arabidopsis GAUTs have a distribution comparable to the poplar orthologs, with the exception of GAUT2, which is absent in poplar. Rice, however, has no orthologs of GAUTs 2 and 12 and has multiple apparent orthologs of GAUTs 1, 4, and 7 compared with eitherArabidopsis or poplar. The cell wall glycosyl residue compositions of 26 homozygous T-DNA insertion mutants for 13 of 15 Arabidopsis GAUTgenes reveal significantly and reproducibly different cell walls in specific tissues of gaut mutants 6, 8, 9, 10, 11, 12, 13, and 14 from that of wild-type Arabidopsis walls. Pectin and xylan polysaccharides are affected by the loss of GAUT function, as demonstrated by the altered galacturonic acid, xylose, rhamnose, galactose, and arabinose composition of distinct gaut mutant walls. The wall glycosyl residue compositional phenotypes observed among the gaut mutants suggest that at least six different biosynthetic linkages in pectins and/or xylans are affected by the lesions in these GAUTgenes. Evidence is also presented to support a role for GAUT11 in seed mucilage expansion and in seed wall and mucilage composition.

Analysis of Gene Expression Patterns during Seed Coat Development in Arabidopsis

The seed coat is important for embryo protection, seed hydration, and dispersal. Seed coat composition is also of interest to the agricultural sector, since it impacts the nutritional value for humans and livestock alike. Although some seed coat genes have been identified, the developmental pathways controlling seed coat development are not completely elucidated, and a global genetic program associated with seed coat development has not been reported. This study uses a combination of genetic and genomic approaches in Arabidopsis thaliana to begin to address these knowledge gaps. Seed coat development is a complex process whereby the integuments of the ovule differentiate into specialized cell types. In Arabidopsis, the outermost layer of cells secretes mucilage into the apoplast and develops a secondary cell wall known as a columella. The layer beneath the epidermis, the palisade, synthesizes a secondary cell wall on its inner tangential side. The innermost layer （the pigmented layer or endothelium） produces proanthocyanidins that condense into tannins and oxidize, giving a brown color to mature seeds. Genetic separation of these cell layers was achieved using the ap2-7 and tt16-1 mutants, where the epidermis/palisade and the endothelium do not develop respectively. This genetic ablation was exploited to examine the developmental programs of these cell types by isolating and collecting seed coats at key tran- sitions during development and performing global gene expression analysis. The data indicate that the developmental programs of the epidermis and the pigmented layer proceed relatively independently. Global expression datasets that can be used for identification of new gene candidates for seed coat development were generated. These dataset provide a comprehensive expression profile for developing seed coats in Arabidopsis, and should provide a useful resource and reference for other seed systems.