Chlamydia trachomatis contains a protein similar to the Legionella pneumophila mip gene product

A 27kDa Chlamydia trachomatis L2 protein was characterized by the use of monoclonal antibodies and by two-dimensional gel electrophoresis. The protein was shown to be located in the membrane of reticulate bodies as well as elementary bodies. Its synthesis could be detected from 10 hours post-infection. Cloning and sequence analysis of the distal part of the gene revealed an open reading frame of 175 amino acids. Comparison of the deduced amino acid sequence with the NBRF data base revealed significant homology between the 27 kDa chlamydial membrane protein and the product of the macrophage infectivity potentiator (mip) gene of Legionella pneumophila.     

Abnormal scale morphogenesis: relationship of polypeptide patterns to action of the scaleless gene.

The polyacrylamide gradient gel electrophoresis (PAGGE) pattern of polypeptides isolated from normal scuttate scale epidermis of 1-week-old chicks was different from that of the anterior shank epidermis from 1-week-old scaleless mutant chicks. The PAGGE patterns of polypeptides isolated from normal and scaleless reticulate scale epidermis (from 1-week-old chicks) differed by only one band, whereas comparison of mutant's scuttate and reticulate patterns showed three band differences. These data are discussed in relation to the action of the scaleless gene on early morphogenesis of the two types of scales.     

Raman microspectroscopy reveals long‐term extracellular activity of chlamydiae

The phylum Chlamydiae consists exclusively of obligate intracellular bacteria. Some of them are formidable pathogens of humans, while others occur as symbionts of amoebae. These genetically intractable bacteria possess a developmental cycle consisting of replicative reticulate bodies and infectious elementary bodies, which are believed to be physiologically inactive. Confocal Raman microspectroscopy was applied to differentiate between reticulate bodies and elementary bodies of Protochlamydia amoebophila and to demonstrate in situ the labelling of this amoeba symbiont after addition of isotope‐labelled phenylalanine. Unexpectedly, uptake of this amino acid was also observed for both developmental stages for up to 3 weeks, if incubated extracellularly with labelled phenylalanine, and P. amoebophila remained infective during this period. Furthermore, P. amoebophila energizes its membrane and performs protein synthesis outside of its host. Importantly, amino acid uptake and protein synthesis after extended extracellular incubation could also be demonstrated for the human pathogen Chlamydia trachomatis, which synthesizes stress‐related proteins under these conditions as shown by 2‐D gel electrophoresis and MALDI‐TOF/TOF mass spectrometry. These findings change our perception of chlamydial biology and reveal that host‐free analyses possess a previously not recognized potential for direct experimental access to these elusive microorganisms.     

Pollen Morphology of Guttiferae in China

The present paper deals with the pollen morphology of 23 species belonging to 6 genera of Guttiferae occurred in China. All pollen grains have been observed under light microscope, and those of 11 species in 5 genera have been examined with SEM as well. The pollen grains of Guttiferae are subspheroidal, spheroidal or prolate, (17–43) × (15–26)μ in size. Mostly 3-eolporate, less frequently 4-colporate or 5-colporate. The exine is 2-layered, but the occassionally demarcation of these layers is generally indistinct. The exine is 0.8–2.6 μ in thickness. The oramentations of all the pollen grains is generlly finely reticulate under the light microscope. Pollen morphology of the 11 species of 5 genera observed under the SEM is stressed. Their exine oramentations may be classified into four major groups, ie. reticulate, finely reticulate, baculate and perforate. Calophyllum: pollen grains reticulate and rugulo-reticulate. Cratoxylon: pollen grains reticulate, with finely and densely granulate over entire muri. Gareinia: pollen grains baculate, reticulate, and exine with perforate oramentation; in reticulate grains, muri with spinulation. Hypericum: pollen grains reticulate, perforate and finely reticulate. Mesua: pollen grains finely reticulate. From the comparison of pollen morphology, Hypericaceae has much connection with Guttiferae (sensu stricto). Because their pollen grains are all 3-eolporate and the exine is reticulate or oerforate under light mieroseope, but it is different between the pollen grains of Hypericum and those of Guttiferae.     

国产藜科14种植物种皮微形态特征比较研究

应用扫描电子显微镜和光学显微镜观察了中国产藜科(Chenopodiaceae)5族10属14种植物的种子形态和种皮微形态结构。观察结果表明:供试的14种藜科植物的种子多为卵形和圆形,少数为双凸镜形;种皮表面都具有网状纹饰,包括浅网纹、负网纹和穴状网纹。种皮可分为膜质和壳质2类,其中,膜质型种皮表面不光滑,除网状纹饰外,还有瘤状或褶皱状等纹饰,网眼无规则,纹饰排列无序,猪毛菜族(Salsoleae C.A.Mey.)的松叶猪毛菜(Salsola laricifolia Turcz.ex Litv.)及樟味藜族(Camphorosmeae Moq.)的地肤〔Kochia scoparia(L.)Schrad.〕、全翅地肤(K.krylovii Litv.)、黑翅地肤(K.melanoptera Bunge)、雾冰藜〔Bassia dasyphylla(Fisch.et Mey.)O.Kuntze〕、钩刺雾冰藜〔B.hyssopifolia(Pall.)O.Kuntze〕、樟味藜(Camphorosma monspeliaca L.)、兜藜(Panderia turkestanica Iljin.)和棉藜(Kirilowia eriantha Bunge)均属此类;壳质型种皮表面近光滑,网眼规则,排列整齐有序,少数为不规则浅穴,网脊平而不明显或凹陷,滨藜族(Atripliceae C.A.Mey.)的滨藜〔Atriplex patens(Litv.)Iljin.〕、碱蓬族(Suaedeae Reich.)的角果碱蓬〔Suaeda corniculata(C.A.Mey.)Bunge〕、纵翅碱蓬〔S.pterantha(Kar.et Kir.)Bunge〕和异子蓬(Borszczowia aralocaspica Bunge)以及藜族(Chenopodieae C.A.Mey.)的刺藜(Chenopodium aristatum L.)均属此类。各族之间种皮微形态结构也有一定的区别。根据种皮微形态,地肤属(Kochia Roth)与雾冰藜属(Bassia All.)的关系较近,属的界限和部分种类的亲缘关系需要进一步界定。藜科植物种皮表面大部分凹凸不平,这种结构可能与荒漠干旱生境下吸收和保留水分有关。     

中国大蒜芥族植物花粉形态的研究

对中国大蒜芥族10属14种植物花粉形态分别进行了光镜和扫描电镜下的观察研究。结果表明该族花粉形态可划分为4种类型：（1）具3沟,超长球形,网状纹饰,外壁2层;（2）具3沟,超长球形,细网状纹饰,外壁1层;（3）具3沟（偶4沟）,长球形,网状纹饰,外壁2层;（4）具6沟,长球形,网状纹饰,外壁2层。因此,中国大蒜芥族的花粉形态多样性程度较高,说明了它不是一个自然类群,是一个多系类群,这与前人研究结果相一致。另外,本文首次报道十字花科锥果芥属植物具6沟花粉,具6沟花粉在十字花科中极为特殊,所以作者将锥果芥属提升为族级,另立新族,即锥果芥族（Tribe Berteroelleae F．Z．Li,G．Y．Tang ＆ Z．Y．Sun,trib．nov．）。     

Pollen Morphology of Loxostemon (Cruciferae) in China

The present paper deals with the pollen morphology of 10 species and 1 variety of Loxostemon in China. The pollen grains were all examined under light microscope. The pollen grains of Loxostemon are subspheroidal, spheroidal or prolate, 18--33×11.8-28 μ in size, 3-colpate, colpi 15-21 μ long and 1-2 μ wide. The exine is 1.5-3 μ thick with two indistinct or distinct layers. All the pollen grains are generally reticulate under light microscope. They are distinctly or obscurely and finely reticulate. L. axillus and L. repens are generally similar in gross morphology, but the pollen grains of these two species are different. The pollen grains of L. axillus are regularly polygonally reticulate, colpi are acute-ended and the exine is about 3 μ thick, whereas those of L.repens are irregularly polygonally reticulate, colpi are enlarged at both ends and the exine is about 2.8 μ thick. L. incanus and L. stenolobus appear to have similar gross morphology, but the pollen grains of the former have exines with two distinct layers and a densely and finely reticulate ornamentation and those of the latter have exines with two indistinct layers and a flexuosely reticulate ornamentation.     

Pollen Morphology of Dioscorea in China

This paper deals with pollen morphology of 33 species belonging to 5 sections of Dioscorea in China. They were examined under both LM and SEM. The pollen grains of Sect. Stenophora are monocolpate with the size of 17-25.5×26.8-39.1μm, the exine is reticulate, striate, parforate-reticulate or cerebro-reticulate, while those of the other sections are bicolpate, reticulate or cerebro- reticulate with the size of 19.2-26.7×13.9-23.1μm. Based on palynological data Sect. Stenophora may be considered primitive and Sect. Enantiophyllum the most advanced in Dioscorea.     

花楸(Sorbus pohuashanensis)导管分子穿孔板的类型及演化

对花楸茎次生木质部进行离析研究,发现其导管穿孔板有两种类型,即网状穿孔板和单穿孔板,并且还有5种过渡类型,具不同类型穿孔板的导管分子有3种类型,即两端均为网状穿孔板的导管分子;一端为网状穿孔板,另一端为单穿孔板的导管分子;两端的均为单穿孔板的导管分子,在花楸个体发育过程中穿孔板类型的演化重演了系统发育过程中导管网状穿孔板演化成单穿孔板的过程。     

Pollen morphology and its evolutionary significance in Hemerocallis (Liliaceae)

Pollen morphology of 10 species of Hemerocallis was investigated with LM and SEM. In addition to pollen with reticulate sexine, a new verrucate sexine pattern is found in three Chinese endemic species, H. plicata, H. forrestii and H. nana . Between the two typical sexine patterns, there are transitional variants. Also, a new pollen shape, boat-shaped-elliptic, is observed exclusively in H. nana , besides-oblong shape in other species. Phylogenetically, the common reticulate sexine pattern would be more primitive than the verrucate one. The typical reticulate sexine pattern would be basic, from which transitional variants would have derived and finally led to the typical verrucate pattern. Similarly, the common boat-shaped-oblong pollen would be more primitive than the -elliptic one, from which the latter would have derived during phylogenetic development.     

The partition matrix: exploring variable phylogenetic signals along nucleotide sequence alignments

The partition matrix is a graphical tool for comparative analysis of nucleotide sequences following alignment. It is particularly useful for investigating the divergent phylogenies of sequence regions undergoing reticulate evolution. A partition matrix is generated by determining the consistency of the parsimoniously informative sites in a set of aligned sequences with the binary partitions inferred from the sequences. Since the linear order of sites is maintained, the matrix can be used to assess whether the distribution of sites either supporting or conflicting with particular partitions changes along the length of the alignment. The usefulness of the matrix in allowing visual identification of differences in evolutionary history among regions depends on the order in which partitions are shown; several suitable ordering schemes are proposed. We demonstrate the use of the partition matrix in interpreting the evolution of the pseudoautosomal boundary region on the sex chromosome of catarrhine primates. Its routine use should help to avoid attempts to derive single phylogenies from sequences whose evolution has been reticulate and to identify the gene conversion or recombination events underlying the reticulation. The method is relatively fast. It is exploratory, and it can form the basis for more formal analysis, which we discuss.      

Avian scale development. VI. Ultrastructure of the keratinizing cells of reticulate scales

Reticulate scales develop as radial symmetrical anlagen, in contrast to scuttate scales which appear initially as “epidermal placodes.” Unlike scuttate scales whose outer and inner epidermal surfaces elaborate β-and α-type keratins, respectively, reticulate scales elaborate only one type of epidermal surface which has been reported to give an α-type, X-ray diffraction pattern. We find that, histologically and ultrastructurally, this surface differs from either epidermal surface of scuttate scales. The keratinizing cells become filled with long interweaving bundles of α-filaments which aggregate into rather homogeneous α-fibrils. Keratohyalin granules, which have been shown to be associated with other keratinizing regions in the bird, do not form during the keratinization of reticulate scale epidermis.     

Retinoic acid induction of featherlike structures from reticulate scales

Retinoic acid-induced transformation of reticulate scales to feather-like structures (Dhouailly and Hardy, '78) provides a useful model to study biochemical differentiation in avian skin. In this study, immunofluorescent analysis of reticulate scale-feathers (RSFs) indicates that they contain beta keratin in feather barbs and, thus, are true feathers, biochemically. Epidermal cells that would otherwise produce only alpha keratin in reticulate scales are induced to reorganize and differentiate into barb ridge cells that accumulate feather beta keratins. The mechanism for these dramatic morphological and biosynthetic responses to retinoic acid is unknown.     

Modelling phylogenetic relationships using reticulated networks

Makarenkov, V., Legendre, P. & Desdevises, Y. (2004). Modelling phylogenetic relationships using reticulated networks. —  Zoologica Scripta , 33 , 89–96.
Most traditional methods of phylogenetic analysis assume that species evolution can be represented by means of a bifurcating tree model. In many phylogenetic situations, however, some of the evolutionary links between species are due to reticulate evolution. For instance, reticulate models can adequately describe such complicated mechanisms as lateral gene transfer in bacteria or species hybridization. The theoretical concepts of reticulate evolution developed in the 1980s and 1990s need to be supported by appropriate analytical tools and software. In this paper, we present the main features of a new distance-based method for modelling phylogenetic relationships among species by means of reticulated networks (RNs). The method uses the least-squares model to build a RN by gradually improving upon the solution provided by a phylogenetic tree. A computer program facilitating the reconstruction and visualization of reticulate phylogenies is made available to researchers. In the application section, we illustrate the usefulness of the method by studying the evolution of honeybees (genus Apis ). The method for reconstructing RNs has been included in the T-Rex ( Tree and Reticulogram Reconstruction ) package recently developed by the first-named author.     

From a phylogenetic tree to a reticulated network.

In many phylogenetic problems, assuming that species have evolved from a common ancestor by a simple branching process is unrealistic. Reticulate phylogenetic models, however, have been largely neglected because the concept of reticulate evolution have not been supported by using appropriate analytical tools and software. The reticulate model can adequately describe such complicated mechanisms as hybridization between species or lateral gene transfer in bacteria. In this paper, we describe a new algorithm for inferring reticulate phylogenies from evolutionary distances among species. The algorithm is capable of detecting contradictory signals encompassed in a phylogenetic tree and identifying possible reticulate events that may have occurred during evolution. The algorithm produces a reticulate phylogeny by gradually improving upon the initial solution provided by a phylogenetic tree model. The new algorithm is compared to the popular SplitsGraph method in a reanalysis of the evolution of photosynthetic organisms. A computer program to construct and visualize reticulate phylogenies, called T-Rex (Tree and Reticulogram Reconstruction), is available to researchers at the following URL: www.fas.umontreal.ca/biol/casgrain/en/labo/t-rex.     

Avian scale development. Absence of an “epidermal placode” in reticulate scale morphogenesis

Timed-sequence studies have shown that reticulate scales on the ventral footpads of birds do not undergo “epidermal placode” formation during their morphogenesis, but arise as symmetrical evaluations similar to the scales of snakes and lizards. Unlike the scutellate scales on the dorsal surface of the foot, in which the formation of an “epidermal placode” and its subsequent morphogenesis result in distinct outer and inner epidermal surfaces, the reticulate scales elaborate only one type of epidermal surface.     

Purification and Chemical Composition of Reticulate Bodies of the Meningopneumonitis Organisms

Reticulate bodies of the meningopneumonitis (MP) microorganism were purified from L cells 18 hr after infection by the combination of differential centrifugation in 30% sucrose solution and potassium tartrate density gradient centrifugation. It was ascertained by electron microscopy that purified preparations of reticulate bodies obtained were almost entirely free of host-cell components and of infectious elementary bodies of MP microorganisms. Purified reticulate bodies were easily disrupted by mechanical agitation, and it was observed in shadowed preparation that ribosome-like particles 15 mmu in diameter were scattered from broken reticulate bodies. In shadowed preparations, reticulate bodies were found to range in size from 1.0 to 1.6 mu in diameter, but in cross-section the range was 0.5 to 1.0 mu. In these preparations, the purified reticulate bodies were irregular in shape, round or oval, and were composed of rather homogenous, amorphous, or reticulate material with moderate density. Some particles exhibited a less-dense internal structure, in which a coarse fibrous reticulum was seen. Chemical fractionation of (32)P-labeled purified reticulate bodies showed that they contained three times more ribonucleic acid (RNA) than deoxyribonucleic acid, with the RNA being composed primarily of 21S, 16S, and 4S RNA. No infectivity of purified reticulate bodies could be demonstrated.     

PATTERN DETERMINATION OF THE EXINE IN CAESALPINIA JAPONICA (LEGUMINOSAE: CAESALPINIOIDEAE)

Exine development in Caesalpinia japonica Sieb. et Zucc. (Leguminosae) was studied by a combination of transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM) using a freeze-fracture method, with special attention to the initial process of exine pattern formation. The present study confirmed that the exine pattern is determined by the plasma membrane of microspores enclosed in the callose wall at the early tetrad stage. The plasma membrane, exclusive of the future apertures, invaginates and takes the form of a reticulate pattern. The reticulate pattern corresponds to the mature exine ornamentation. Protectum is the first to be laid down on the reticulate patterned plasma membrane. Probacules are initiated under the protectum and elongate basally on protruding sites of the plasma membrane. Primexine matrix is formed in coincidence with the probacules. After the protectum and probacules are completed within the callose wall, the invaginating plasma membrane becomes smooth. After the dissolution of the callose wall, endexine is organized by the accumulation of lamellated structures, and a foot layer is formed by the deposition of nonlamellated components on the developing endexine.     

临安旧石器调查简报

本文记述了2004年采集自临安市5个地点的旧石器时代的石制品22件,其中1件出自下蜀土层中,其余均为脱层标本。石器中以厚石片为毛坯加工成器的比例明显高于西苕溪流域,应引起关注。出自下蜀土层的标本属于晚更新世晚期,有网纹印痕的标本可能归旧石器时代早期至中期,而没有网纹印痕的脱层标本的年代应不早于网纹红土的年代。