Development of ovule and seed in Rapateaceae

VENTURELLI, M. & BOUMAN, F., 1988. Development of ovule and seed in Rapateaceae. The structure of the ovules and/or seeds of twelve species of Rapateaceae were studied, some additional embryological characters also being recorded. The ovules are always anatropous, bitegmic and crassinucellate, but they differ in the shape, size and in thickness of the outer integument. In Rapateaceae the outer integument is initiated subdermally. The seed coat of the Rapateaceae shows two mechanical layers: an endotesta with silica present as bodies or as incrustations in cell walls, in conjunction with an exotegmen with a jigsaw cell pattern complicated by a labyrinth-like sculpturing of the outer cell walls. The innermost layer of the inner integument is tanniniferous. Large hilar scars with tracheidal plates on the corresponding fruit wall and a persistent obturator are recorded in Rapateaceae. On the basis of embryological characters the family fits well into the Commelinales. Testa structure most closely resembles that of the Commelinaceae. The differences in ovule and seed structure agree with the currently accepted tribal classification.     

Transfer cells in the seeds of Boraginales

The presence of transfer cells (TCs) in the seeds of Boraginales (Boraginaceae s.s. , Hydrophyllaceae, Heliotropiaceae, Ehretiaceae, Cordiaceae and Lennoaceae) has been reported but has not hitherto been studied systematically. This study, surveying the seed anatomy of 50 species of Boraginales, demonstrates that in Heliotropiaceae, Cordiaceae, Ehretiaceae and Lennoaceae, TCs are found in an uninterrupted course from the placenta via the funicle to the seed coat. These families are characterized by indehiscent fruits with a protective endocarp. The TCs may act as a sponge, thus promoting rapid germination when sufficient water is available. In Hydrophyllaceae, which have capsular fruits, TCs are often found but have a different structure and are restricted to the seed coat. Boraginaceae s.s. on the other hand are characterized by a complete absence of TCs in their seeds. The presence of TCs in seeds is considered as a synapomorphic trait and appears to be phylogenetically informative.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 155−164.     

Morphology and anatomy of physical dormancy in Ipomoea lacunosa: identification of the water gap in seeds of Convolvulaceae (Solanales)

BACKGROUND AND AIMS: Convolvulaceae is the most advanced plant family (asterid clade) that produces seeds with physical dormancy (water-impermeable seed coat). There are several different opinions about the nature of the specialized structure ('water gap') in the seed coat through which water initially enters seeds of Convolvulaceae, but none of them has been documented clearly. The primary aim of the study was to identify the water gap in seeds of Ipomoea lacunosa (Convolvulaceae) and to describe its morphology, anatomy and function. METHODS: Light microscopy, scanning electron microscopy, tissue-sectioning, dye-tracking and blocking experiments were used to describe the morphology, anatomy and function of the water gap in seeds of I. lacunosa. KEY RESULTS: Dormancy-breaking treatments caused slits to form around the two bulges on the seed coat adjacent to the hilum, and dye entered the seed only via the disrupted bulges. Bulge anatomy differs from that of the rest of the seed coat. Sclereid cells of the bulges are more compacted and elongated than those in the hilum pad and in the rest of the seed coat away from the bulges. CONCLUSIONS: The transition area between elongated and square-shaped sclereid cells is the place where the water gap opens. Morphology/anatomy of the water gap in Convolvulaceae differs from that of taxa in the other 11 angiosperm plant families that produce seeds with physical dormancy for which it has been described.     

Development of the ovule and seed in Costus cuspidatus (N.E.Br.) Maas (Zingiberaceae), with special reference to the formation of the operculum

The ovule primordium of Costus is trizonate and both its integuments are dermally initiated. With other evidence, this strongly suggests that most, if not all, monocotyledons have dermally initiated integuments, indicating a derived status. The mature seed coat of Costus is completely formed by the outer integument and its principal mechanical layer is the endotesta.
The seed of Costus has an aril, an operculum and a micropylar collar. These structures, characteristic of zingiberalean seeds, are each initiated in a different, specific cell layer of the exostome. The aril is completely dermally initiated. The parenchymatic part of the operculum and the micropylar collar are of dual origin, namely dermal at me integumentary region and subdermal at the raphe.     

Influence of buffer ions and divalent cations on coated vesicle disassembly and reassembly

Disruption of the coat of coated vesicles is accompanied by the release of clathrin and other proteins in soluble form. The ability of solubilized coated vesicle proteins to reassemble into empty coats is influenced by Mg²⁺, Tris ion concentration, pH, and ionic strength. The proteins solubilized by 2 M urea spontaneously reassemble into empty coats following dialysis into isolation buffer (0.1 M MES–1 mM EGTA–1 mM MgCl₂–0.02% NaN₃, pH 6.8). Such reassembled coats have sedimentation properties similar to untreated coated vesicles. Clathrin is the predominant protein of reassembled coats; most of the other proteins present in native coated vesicles are absent. We have found that Mg²⁺ is important in the coat assembly reaction. At pH 8 in 0.01 M or 0.1 M Tris, coats dissociate; however, 10 mM MgCl₂ prevents dissociation. If the coats are first dissociated at pH 8 and then the MgCl₂ raised to 10 mM, reassembly occurs. These results suggest that Mg²⁺ stabilizes the coat lattice and promotes reassembly. This hypothesis is supported by our observations that increasing Mg²⁺ (10 μM–10 mM) increases reassembly whereas chelation of Mg²⁺ by (EGTA) inhibits reassembly. Coats reassembled in low-Tris (0.01 M, pH 8) supernatants containing 10 mM MgCl₂ do not sediment, but upon dialysis into isolation buffer (pH 6.8), these coats become sedimentable. Nonsedimentable coats are noted also either when partially purified clathrin (peak I from Sepharose CL4B columns) is dialyzed into low-ionic-strength buffer or when peaks I and II are dialyzed into isolation buffer. Such nonsedimentable coats may represent intermediates in the assembly reaction which have normal morphology but lack some of the physical properties of native coats. We present a model suggesting that tightly intertwined antiparallel clathrin dimers form the edges of the coat lattice.     

Systematic anatomy of Oceanopapaver, a monotypic genus of the Gapparaceae from New Caledonia

Evidence from vegetative anatomy, reproductive morphology, and palynology does not support a relationship of Oceanopapaver with Cistaceae, Cruciferae, Flacourtiaceae, Papaveraceae, and Tiliaceae, but suggests placement of the genus in Capparaceae. The apparent occurrence of myrosin cells, among other features, effectively excludes all of the aforenoted families except Capparaceae and Cruciferae. However, multicellular non-glandular trichomes, bracteate inflorescences, sepals and petals each occasionally other than four per flower, presence of an androgynophore, numerous stamens, tricolporate and binucleate pollen, the unilocular mature ovary, the stipitate fruit, and the exotegmic seed in Oceanopapaver favour Capparaceae over Cruciferae. Floral histology and vasculature provide no clues about the relationships of Oceanopapaver. A few features are anomalous, most notably the presence of secretory canals and secretory cells in the genus versus their absence in Capparaceae and their rarity in Cruciferae, the trichomic floral nectary in the genus versus the massive, non-trichomic nectaries in these two families, and the straight embryo in the genus versus the more or less curved or folded embryo in the two families. The fleshy endosperm in Oceanopapaver has counterparts in a few Capparaceae, contrary to previous claims that endosperm is absent or scanty in this family. The report of stamen fascicle traces for Oceanopapaver is the first for Capparaceae, but these should be sought elsewhere in the family. Within Capparaceae the genus fits best in Capparoideae compared to Cleomoideae or the nine other very restrictive subfamilies variously proposed for Capparaceae. There is no justification for the monotypic segregate Oceanopapaveraceae. The phylogenetic and functional anatomy of vegetative and reproductive structures is discussed.     

结构植物学在中国的五十年发展

结构植物学由植物解剖学发展而来,是植物学的一个重要分支学科.本文根据其近代的发展,分别就植物发育解剖学向植物发育生物学的发展、植物比较解剖学向植物系统发育生物学的发展,以及环境生态结构植物学三个主要部分简要介绍了50年来在我国的发展,并对它们的发展趋势进行了预测.     

结构植物学在中国的五十年发展

结构植物学由植物解剖学发展而来 ,是植物学的一个重要分支学科。本文根据其近代的发展 ,分别就植物发育解剖学向植物发育生物学的发展、植物比较解剖学向植物系统发育生物学的发展 ,以及环境生态结构植物学三个主要部分简要介绍了 5 0年来在我国的发展 ,并对它们的发展趋势进行了预测     

Simultaneous accumulation of multiple viral coat proteins from a TEV-NIa based expression vector

We previously described an expression cassette that relies on the tobacco etch virus (TEV) nuclear inclusion a (NIa) protease and leads to the coordinated accumulation of multiple proteins through self processing of a polyprotein [21]. However, low levels of proteins accumulated when the full-length protease was encoded within the polyprotein [22].Studies were conducted to evaluate whether the disruption of NIa nuclear localization would affect the levels of proteins produced via the cassette. Modifications comprised either removal of its nuclear localization signals (NLSs), removal of the VPg domain (which includes the NLSs), and fusion to the 6 kDa protein, previously demonstrated to be a viral cytoplasmic anchor [28]. In in vitro translation reactions and in vivo protoplast experiments the modified NIa retained sequence-specific proteolysis. Moreover, the removal of the NLSs correlated with an increase in GUS reporter accumulation. The modified cassette, pPRO10, led to the synthesis of up to three viral coat protein (CPs) in addition to NIa. However, the accumulation of proteins in protoplasts depended upon the position of the CP coding sequence within the cassette as well as on the stability of the protein.     

Comparative anatomy and systematics of woody Saxifragaceae. Aphanopetalum Endl.

The floral and vegetative anatomy of the small Australian genus Aphanopetalum were studied. Wood is described for the first time and is characterized by predominantly solitary pores, scalariform vessel element perforation plates with low bar numbers, imperforate tracheary elements with distinctly bordered pits, sparse axial parenchyma, and a combination of homocellular and heterocellular rayS. Starch occurs in both axial and ray parenchyma of the wood. Stems possess unilacunar, one-trace nodes and the uncommon feature of an endodermis with well-defined Casparian stripS. Leaves have anomocytic stomata, a bifacial mesophyll and semicraspedodromous venation or a combination of semicraspedodromous and brochidodromous venation. The tetramerous flowers are apetalous or have minute petals. The compound, half-inferior gynoecium consists of essentially totally united carpels. The pattern of floral vascularization resembles different Saxifragaceae sensu lalo in that the compound sepal-plane and petal-plane traces give rise to staman bundles as well as sepal, petal, and carpel wall venation in their respective planes. The ventral ovarian bundles are fused into a single ventral complex that subdivides at the top of the ovary to form ventral bundles and to supply the one ovule in each locule. Vegetative and floral features provide compelling evidence to suggest that Aphanopetalum has its nearest relatives among the Saxifragaceae sensu lato rather than Cunoniaceae. The genus is probably best treated as forming its own subfamily (or family) among the saxifragaean alliance.     

A 19‐Mb de novo deletion on BTA 22 including MITF leads to microphthalmia and the absence of pigmentation in a Holstein calf

Mutations in MITF lead to a large variety of phenotypes in human, mice and other species. They mostly affect pigmentation and hearing, whereas in mice, they may additionally cause microphthalmia and osteopetrosis. In this study, we report a single case of a Holstein calf with lack of pigmentation and microphthalmia born to healthy parents. Mendelian analysis of high‐density SNP genotypes reveals a large number of parentage errors showing missing paternal alleles in the offspring, indicating a deletion encompassing 19 Mb on BTA 22. The genomic deletion affects the paternal allele and includes MITF and 131 other annotated genes. As the calf shows only one copy of the BTA 22 segment, the observed phenotype is probably caused by haploinsufficiency of the genes in that genomic region. Both the observed lack of skin pigmentation and reduced eye size can most likely be explained by a lack of MITF function.     

Imbibition of Swietenia macrophylla (Meliaceae) seeds: the role of stomata

BACKGROUND AND AIMS: The occurrence of stomata in seed coats is uncommon and there is limited information about their function(s). The aim of this study was to verify the distribution of stomata in seed coats of Swietenia macrophylla and to relate it to the imbibition process and aspects of the structure of the outer integument layers. METHODS: For the structural and ultrastructural studies, the seeds were processed using the usual techniques and studied under light and scanning electron microscopes. Histochemical tests were employed to identify the cell wall composition in the different seed coat portions. To assess the role of the stomata in the imbibition, non-impervious seeds were compared with partially impervious ones, in which only the embryo, median or hilar regions were left free. Further, the apoplastic pathway marker was employed to confirm the role of the stomata as sites of water passage during imbibition. KEY RESULTS: A positive relationship was observed between seed coat thickness and stomata density. The stomata were devoid of movement, with a large pore. They occurred in large numbers in the embryo region and extended with lower frequency towards the wing. Imbibition rates were related to stomata density, suggesting that the stomata act as preferential sites for water entry in the S. macrophylla seeds. CONCLUSIONS: At maturity, the stomata in the seed coat play a significant role in seed imbibition. The data may also infer that these permanently opened stomata have an important role in gas exchange during seed development, aiding embryo respiration.     

Seed coat structure and development in Solanum L. section Solanum (Solanaceae)

Seed coat structure in Solanum L. section Solanum (Solanaceae). Seed coat structure in Solanum L. section Solanum was examined using SEM. The seed coat patterns observed were fairly uniform throughout the section, and thus of little diagnostic use. Moreover, all species are characterized by their seeds being covered by hairlike structures, which are bands of lignified thickening in the lateral (and basal) walls of the outer epidermal cells of the testa, and which only become obvious when the seeds are wetted. The development of the seed coat and its characteristic thickening was followed from the unfertilized ovule to the mature seed in vouchered material of Solanum nigrum L. since this species is the generic type, using sections of freshly fixed material.     

Comparing the accuracy and precision of three techniques used for estimating missing landmarks when reconstructing fossil hominin crania

In some primate species, pelage colorations at birth contrast with adult colorations. The intensity of natal coats and their phylogenetic distribution is highly variable within primates. Natal coat coloration seems to change to adult coloration in most species when infants become independent from their mothers, but an accepted functional explanation for natal coats is not available. Here we describe pelage coloration change in sexually dichromatic redfronted lemurs (Eulemur fulvus rufus) in Kirindy Forest, and propose a new functional hypothesis for this phenomenon. In this species, infants are born with adult male coloration and female infants subsequently undergo a change in coloration. Using digital pictures and behavioral data collected on eight mother-offspring dyads from birth until the end of the coloration change, we 1) described timing and pattern of pelage developmentin redfronted lemur infants and 2) examined behavioral developmental correlates of the coloration change. The color change took place between 7 and 17 weeks of age and coincided with advanced physical independence; a pattern also found in monochromatic primate species with natal coats. No behavioral differences between male and female infants were found. Hypotheses about the ultimate function of natal coats focusing on enhanced infant care or reduced infanticide risk did not explain the pelage change in redfronted lemurs. The natal pelage pattern in this species may instead serve as sexual mimicry. Accordingly, female infants may mimic males during the most vulnerable developmental phase to avoid sex-specific aggression by adult females in a species with intense female-female aggression and competition.     

The Relationship Between Coat Color and Aggressive Behaviors in the Domestic Cat

The authors explored a possible relationship between coat color and aggressive behaviors in the domestic cat. This study used an Internet-based survey to collect information on coat color, affiliative behaviors toward cats/humans, agonistic behaviors toward cats/humans, other “problem” behaviors, and cat and guardian demographic data. A total of 1,432 cat guardians completed the online survey; after exclusions based on study protocol, data analysis included 1,274 completed surveys. Guardians reported sex-linked orange female (tortoiseshells, calicos, and “torbies”), black-and-white, and gray-and-white cats to be more frequently aggressive toward humans in 3 settings: during everyday interactions, during handling, and during veterinary visits. Kruskal-Wallis 1-way analysis of variance was used to compare possible differences between the 2 sexes and among different coat colors. Analyses of aggression due to handling, as well as aggression displayed during veterinarian visits, showed little difference among coat colors in these settings.     

苏芸金杆菌伴孢晶体和芽孢孢衣的蛋白质组分及其与毒力的关系

研究了苏芸金杆菌(Bacillus thuringiensis)3个变种6个菌株的提纯伴孢晶体和芽孢对大蜡螟(Galleria mellonella)和大菜粉蝶(Pieris brassicae)的毒力、晶体的蛋白质和多肽成分及芽孢衣中的类晶体蛋白质成分.生物测定表明,晶体毒力高于芽孢,在总数量相同的情况下,晶体和芽孢近1:1的混合物的毒力高于单独的晶体或芽孢.芽孢衣中存在一种类似晶体蛋白质的成分,无晶体突变株及无效野生株的芽孢则无此种蛋白质且对两种昆虫无毒.变种wuhanensis和变种galleriae的晶体含MW138000的主要蛋白质和63000的次要蛋白质,经碱性缓冲液溶解后,上清液含MW138000的蛋白质,沉淀中含MW63000的蛋白质;变种aizawai的晶体中仅含138000的蛋白质.对大蜡螟无毒的HD-11(var.aizawai)晶体的蛋白质成分有别于上述晶体,其胰蛋白酶消化物的SDS凝胶电泳图型显示少2条多肽带,但对大菜粉蝶仍有效.结果表明,苏芸金杆菌的芽孢在昆虫病理中有重要作用,伴孢晶体的蛋白质和多肽成分与它们对昆虫的毒力特性之间有密切关系.     

种壳厚度对鼠类种子扩散行为及种子命运的影响

种子扩散是植物更新和扩大分布区的一种重要途径。鼠类采取不同的种子扩散和贮藏策略,以应对食物短缺,同时也促进了植物种子扩散。为应对鼠类对植物种子的过度取食,种子进化出了一系列物理、化学等防御特征。其中种壳厚度作为一种物理防御策略,是影响鼠类贮藏行为和种子命运的关键因素。本研究拟通过去除天然栓皮栎（Quercus variabilis）种子的外壳,再在种仁外包被1、2、4、6不同层数的聚乙烯薄膜,模拟种壳厚度,准确控制种壳厚度。2020年10月—2021年1月,在四川都江堰森林生境中释放人工种壳包被的种子,研究人工种壳厚度对鼠类介导的种子扩散和命运的影响。结果表明：（1）鼠类优先扩散种壳较薄（1层薄膜包被）的人工种子;随着种壳厚度的增加,扩散速率逐渐降低,种壳最厚（6层薄膜包被）的种子扩散最慢（P < 0.001）;（2）鼠类喜好分散贮藏1层、2层薄膜包被的种子;当种壳厚度增加至包被4层、6层薄膜时,分散贮藏比例显著降低（P < 0.05）;（3）鼠类偏好集中贮藏4层薄膜包被的种子（P < 0.05）;（4）不同种壳厚度的种子扩散距离无显著差异（P > 0.05）;（5）种壳较薄（1层薄膜包被）的种子分散贮藏率在3 m范围内比例较高。采用聚乙烯薄膜包被是模拟种子外壳的可行方法,并可用于评估种壳厚度对鼠类种子贮藏行为和种子命运的影响等相关研究。     

Two SNPs in the SILV gene are associated with silver coat colour in ponies

In horses, a pigment dilution acting only on black eumelanin is the so-called silver coat colour, which is characterized by a chocolate-to-reddish body with a white mane and tail. Using information from other species, we focused our study on SILV as a possible candidate gene for the equine silver phenotype. A 1559-bp genomic fragment was sequenced in 24 horses, and five SNPs were detected. Two of the five SNPs (DQ665301:g.697A>T and DQ665301:g.1457C>T) were genotyped in 112 horses representing eight colour phenotypes. Both mutations were completely associated with the silver phenotype: all eumelanin-producing horses (blacks and bays) with atypical white mane and tail were carriers of the [g.697T; g.1457T] haplotype. We identified this haplotype as well as the silver phenotype only in Shetland ponies and Icelandic horses. Horses without eumelanin (chestnuts) were carriers of the [g.697T; g.1457T] haplotype, but they showed no phenotypic effect. The white or flaxen mane often detected in chestnuts is presumably based on another SILV mutation or on polymorphisms in other genes.