Male spike strobiles with Gnetum affinity from the Early Cretaceous in western Liaoning,Northeast China

A fossil with Gnetum affinity was found in the Jianshangou Member （Barremian Age） of the Yixian Formation （Lower Cretaceous Epoch） of the Jehol Group in western Liaoning, northeastern China. The single fossil specimen is represented by both elongate-cylindrical male spike strobiles which borne within a nodal bract of cauliflorous branch. The spike strobiles have apparent nodes, invisible internodes, and numerous verticillate involucral collars. The microsporangiate units within involucral collars are not seen. The male spike strobiles with verticillate involucral collars occur exclusively in Gnetum; hence, the fossil strobiles are attributed to a new taxon, Khitania columnispicata gen. ＆ sp. nov., being closely related to Gnetum. The general isotopic dating suggests an age of Barremian, ca. 125-122 million years （Myr） ago for the Jianshangou Member. The palaeoecological and palaeoclimatic inference based on the compositions of flora and fauna, and lithological characters of the fossil locality suggests that the fossil plants grew in a subtropical mesophytic forest and under a warmer climate. The remains of male spike strobiles are the first record of gnetalean macrofossil. It documents the evolution of the distinct gnetoid morphology and indicates a wider range of distribution of Gnetaceae in the Early Cretaceous than present day.     

A PRELIMINARY RECOGNITION OF THE GENUS CHINOCYTHERE (OSTRACODA)

Chinocythere was established as a new genus in 1978 based on fossil ostracodes found from the Palaeogene Shahejie and Dongying Formations along the coastal region of the Bohai Sea. It was also found from the Palaeogene Weizhou and Liushagang Formations of the continental shelf in the northern part of the South China Sea as well as from the early Oligocene Nadou Formation in the Baise basin in Guangxi. In historical geology, Chinocythere first appeared and flourished in Eocene and then gradually declined and became extinct in Oligocene. Despite of its narrow horizontal distribution and limited vertical extension in the geologic section, there are a great many of varieties in this genus, with up to 87 species already published representing the coastal region of the Bohai Sea alone, this in a sense, affords us an invaluable condition for the study of its evolution.     

A Dispersal and Vicariance Analysis of the Genus Caragana Fabr.

The genus Caragana Fabr., consisting of approximately 70 species, has a temperate Asian distribution and occurs mainly in the drought and cold regions of the northwestern and southwestern Tibetan Plateau of China. The distribution pattern of the genus was investigated using dispersal-vicariance analysis （DIVA）, The results indicate that vicariance versus dispersal plays a major role in the evolution of the genus and that short-distance dispersal also exists. There is no fossil record of this genus. Therefore, Caragana is inferred as an advanced taxon in terms of its limited temperate Asian distribution. Based on the morphological variation and ecological adaptation in Caragana, the generic speciation is postulated to be related to the uplifting of the Tibetan Plateau and to the increasing arid conditions of Central Asian lands since the Neogene. The Mongolian Plateau and the Tibetan Plateau are hypothesized as the barriers of vicariance between East Asia and western Central Asia.     

Late Pliocene diversity and distribution of Drynaria(Polypodiaceae) in western Yunnan explained by forest vegetation and humid climates

The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang,Su et Zhou(Polypodiaceae), from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan.These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene.This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.     

CHAROPHYTES OF NANXIONG BASIN, GUANGDONG AND ITS CRETACEOUS-TERTIARY BOUNDARY

The present paper makes a second study on the fossil oogonia of the Charophyta from the Nanxiong Basin, Guangdong. The first study (Huang Ren-jin, 1979) concerned the charophyte fossil of Late Cretaceous and Paleogene from the same basin, while the present one contains Cretaceous-Tertiary boundary and charopbytes of this basin.     

The earliest Timematids in Burmese amber reveal diverse tarsal pads of stick insects in the mid‐Cretaceous

Many extant insects have developed pad structures, euplantulae or arolia on their tarsi to increase friction or enhance adhesion for better mobility. Many polyneopteran insects with euplantulae, for example, Grylloblattodea, Mantophasmatodea and Orthoptera, have been described from the Mesozoic. However, the origin and evolution of stick insects' euplantulae are poorly understood due to rare fossil records. Here, we report the earliest fossil records of Timematodea hitherto, Tumefactipes prolongates gen. et sp. nov. and Granosicorpes Urates gen. et sp. nov., based on three specimens from mid-Cretaceous Burmese amber. Specimens of Tumefactipes prolongates gen. et sp. nov. have extremely specialized and expanded euplantulae on their tarsomere II. These new findings are the first known and the earliest fossil records about euplantula structure within Phasmatodea, demonstrating the diversity of euplantulae in Polyneoptera during the Mesozoic. Such tarsal pads might have increased friction and helped these mid-Cretaceous stick insects to climb more firmly on various surfaces, such as broad leaves, wetted tree branches or ground. These specimens provide more morphological data for us to understand the relationships of Timematodea, Euphasmatodea, Orthoptera and Embioptera, suggesting that Timematodea might be monophyletic with Euphasmatodea rather than Embioptera and Phasmatodea should have a closer relationship with Orthoptera rather than Embioptera.     

MAMMIFRES DE SANSAN,coordinated by Stéphane Peigné and Sevket Sen, 2012. Mémoires du Muséum National d'Histoire naturelle,Publication Scientifi que 203, 709 pages,ISBN 978-2-85653-681-0.Mammifères de Sansan,key volume on a historical locality

正The Muséum National d’Histoire naturelle,via the able hands of Stéphane Peignéand Sevket Sen,has produced a massive scientific work that compiles advanced studies on the diverse mammalian fossil assemblage of Sansan,Gers,southwestern France.Servais et al.(2012)called Sansan a"lagersttte",and so it is:a remarkable fossil site that assembles much of the biota of its past community in one place.Sansan is a site complex with adjacent     

Isolation and characterization of glacier VMY22, a novel lytic cold-active bacteriophage of Bacillus cereus

As a unique ecological system with low temperature and low nutrient levels, glaciers are considered a "living fossil" for the research of evolution. In this work, a lytic cold-active bacteriophage designated VMY22 against Bacillus cereus MYB41-22 was isolated from Mingyong Glacier in China, and its characteristics were studied. Electron microscopy revealed that VMY22 has an icosahedral head(59.2 nm in length, 31.9 nm in width) and a tail(43.2 nm in length). Bacteriophage VMY22 was classified as a Podoviridae with an approximate genome size of 18 to 20 kb. A one-step growth curve revealed that the latent and the burst periods were 70 and 70 min, respectively, with an average burst size of 78 bacteriophage particles per infected cell. The pH and thermal stability of bacteriophage VMY22 were also investigated. The maximum stability of the bacteriophage was observed to be at pH 8.0 and it was comparatively stable at p H 5.0–9.0. As VMY22 is a cold-active bacteriophage with low production temperature, its characterization and the relationship between MYB41-22 and Bacillus cereus bacteriophage deserve further study.     

云南路南早第三紀哺乳动物

关于滇东路南地区的第三紀哺乳动物化石及其时代問題,最初曾由楊鈡健、卞美年(1939,1940)及周明鎮(1957)等进行过研究。近几年来,地貭部博物館胡承志先生,以及本所云南野外工作队,对滇东进行了多次調查和化石采集工作,相继在路南以南的扳桥及大可村附近发現了相当丰富的哺乳动物化石。其中絕大部分材料均已研究发表(周, The Tertiary fossil mammals and the fossil bearing beds of Lunan, Yunnan were first studied by Young and Bien (1939). In recent years many new materials had been found and most of them had been investigated and published (Chow, 1957; 1958_1; 1958_2 Chow and Hu, 1959; Chow and Xu, 1961). Chow not only reexamined the collection, which had been preliminarily identified by Young and Bien (1939), and confirmed the age of the fossil bearing sediments to be Latest Eocene, but also pointed out, on the basis of the new materials, that a stratum of Oligocene age occurs in the upper part of the series of Lunan beds. He divided this series into two parts; the upper part of the series was called "Upper Lunan stratum", and dated to be Early Oligocene; the lower part was called "Lower Lunan stratum", and dated to be Latest Eocene.The present paper describes some mammalian fossils recently collected in these beds, and discusses the character and age of the fossil mammalian fauna of Lunan.A list of the fossil mammals described in this paper is given below: Brontotheriidae Rhinotitan quadridens sp. nov. Brontotheriidae indet. Helaletidae Teleolophus medius M. & G. Amynodontidae Amynodon altidens sp. nov. Amynodon sp. of. Metamynodon sp. Rhinocerotidae Prohyracodon progressa Chow & Xu Rhinocerotidae indet. Entelodontidae Eoentelodon yunnanense Chow     

Cyclocarya cf. paliurus （Batal.） Iljinskaja （Juglandaceae） from the Hunchun Formation （Eocene）, Jilin Province, China

The leaflet architecture of Cyclocarya cf. paliurus （Batal.） Iljinskaja from the Hunchun Formation （Middle Eocene） shows similarity to that of modem C. paliurus （Batal.） Iljinskaja and the specimen is the oldest fossil record in Europe and Asia. The distributions of C. cf. paliurus and other fossil records, such as Glyptostrobus, Metasequoia, Nyssa, and Liquidambar, in Hunchun flora show that it would have been a warmer-temperature to subtropical climate in Hunchun District during the Eocene period.     

A LEMUROID PRIMATE FROM THE EOCENE OF LANTIAN,SHENSI

From the Early Tertiary sandstones and clays underlain the Sinanthropus-bearingreddish clays at Chen-Chia-Ou,Lantian District,Shensi(Chang et al.,1964),some mam-malian fossils have recently been collected in a thin layer of intercating chocolate-coloredclays at two outcrops.One is in a ravine named Kongkouwan,from where a singlespecimen of mammalian upper jaw considered here as a new lemuroid primate has beenrecovered.The age of the Early Tertiary beds of the Lantian District,which consist of whitesandstones,buff sands and sandy clays,is not yet precisely known;but the fossil bearinghorizon may be regarded as Late Eocene on basis of the fossil primate noted here.     

Intercontinental and intracontinental biogeography patterns and methods

The study of biogeography has benefited from the exponential increase of DNA sequence data from recent molecular systematic studies, the development of analytical methods in the last decade concerning divergence time estimation and geographic area analyses, and the availability of large-scale distributiofi data of species in many groups of organisms. The underlying principle of divergence time estimation from DNA and protein data is that sequence divergence depends on the product of evolutionary rate and time. With their molecular clock hypothesis, Zuckerkandl and Pauling （1965） separated rates of molecular evolution from time by incorporating fossil evidence. Originally,     

CONCHOSTRACAN ASSEMBLAGE FROM BOTTOM OF ERMAYIN FORMATION, SHAANXI

This paper deals with characteristics of the conchostracan assemblage and describes some new species of fossil conchostracan collected from the bottom of the Ermayin Formation near Changjiayan of Wupu County, Shaanxi in 1983.After studying and comparing this conchostracan assemblage, the writer here suggests that (1) this assemblage is characterized by leading members of Protomonocarina and Euestheria, rare but very important members of Xiangxiella and many members of Palaeolimnadiopsis and Diaplexa; (2) this fossil fauna has a close relation to that of the Heshanggou Formation, but itis more different from that of the Tongchuan Formation.It is of great significance to compare the regional stratigraphical sequence, because the strata containing this conchostracan fauna are more stable in North China.This fossil fauna may be called the Protomonocarina-Euesteria fauna, representing the conchostracan fauna of early Middle Triassic in North China and resembling the Xiangxiella fauna in South China.     

FIRST DISCOVERY OF MEGACEROS (MAMMALIA) IN NINGXI

<正> When I was working in Ningxia Hui Aotonomous Region in 1974, a geologic engineer of Geologic Bureau of Ningxia gave me a fossil mammalian specimen and asked me to identify it. This is the first discovery of Megaceros in Ningxia.     

Repetitive Sequences in Plant Nuclear DNA:Types,Distribution, Evolution and Function

Repetitive DNA sequences are a major component of eukaryotic genomes and may account for up to 90% of the genome size. They can be divided into minisatellite, microsatellite and satellite sequences. Satellite DNA sequences are considered to be a fast-evolving component of eukaryotic genomes, comprising tandemly-arrayed, highly-repetitive and highly-conserved monomer sequences. The monomer unit of satellite DNA is 150–400 base pairs(bp) in length.Repetitive sequences may be species- or genus-specific, and may be centromeric or subtelomeric in nature. They exhibit cohesive and concerted evolution caused by molecular drive, leading to high sequence homogeneity. Repetitive sequences accumulate variations in sequence and copy number during evolution, hence they are important tools for taxonomic and phylogenetic studies, and are known as ‘‘tuning knobs' ' in the evolution. Therefore, knowledge of repetitive sequences assists our understanding of the organization, evolution and behavior of eukaryotic genomes. Repetitive sequences have cytoplasmic, cellular and developmental effects and play a role in chromosomal recombination. In the post-genomics era, with the introduction of next-generation sequencing technology, it is possible to evaluate complex genomes for analyzing repetitive sequences and deciphering the yet unknown functional potential of repetitive sequences.     

MHC Class I Exon 4 in the Multiocellated Racerunners （Eremias multiocellata）： Polymorphism,Duplication and Selection

The major histocompatibility complex （MHC） is a dynamic genetic region with an essential role in the adaptive immunity of jawed vertebrates. The MHC polymorphism is affected by many processes such as birth-and- death evolution, gene conversion, and concerted evolution. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. However, the investigation of this region in nonavian reptiles is still in its infancy. We present the first characterization of MHC class I genes in a species from the family Lacertidae. We assessed genetic diversity and a role of selection in shaping the diversity of MHC class I exon 4 among 37 individuals of Eremias multiocellata from a population in Lanzhou, China. We generated 67 distinct DNA sequences using cloning and sequencing methods, and identified 36 putative functional variants as well as two putative pseudogene-variants. We found the number of variants within an individual varying between two and seven, indicating that there are at least four MHC class I loci in this species. Gene duplication plays a role in increasing copy numbers of MHC genes and allelic diversity in this species. The class I exon 4 sequences are characteristic of low nucleotide diversity. No signal of recombination is detected, but purifying selection is detected in β2-microglobulin interaction sites and some other silent sites outside of the function-constraint regions. Certain identical alleles are shared by Eremias multiocellata and E. przewalskii and E. brenchleyi, suggesting trans-species polymorphism. The data are compatible with a birth-and-death model of evolution.     

A NEW SPECIES OF ALLIGATOR FROM SHANWANG, SHANDONG

<正> A crocodilian specimen is described and identified, as a new species of Alligalor in present paper. The material was collected from the Middle Member of the Shanwang Formation, Linqu County, Shandong Province by the members of the Linqu Paleontological Museum in 1984. Nearly 40 taxa of fossil vertebrates, including fishes, amphibians, reptiles, birds and mammals, have been reproted from this Miocene locality since 1930's (Yian et al. 1983, Qiu et al. 1986). Within the vertebrate fauna the fossil mammals and fishes are very rich, but the other are relatively rare. This is the first record of a crocodilan from the diatomaceous quarry of Shanwang.     

Spontaneous modulation of a dynamic balance between bacterial genomic stability and mutability: roles and molecular mechanisms of the genetic switch

Bacteria need a high degree of genetic stability to maintain their species identities over long evolutionary times while retaining some mutability to adapt to the changing environment.It is a long unanswered question that how bacteria reconcile these seemingly contradictory biological properties.We hypothesized that certain mechanisms must maintain a dynamic balance between genetic stability and mutability for the survival and evolution of bacterial species.To identify such mechanisms,we analyzed bacterial genomes,focusing on the Salmonella mismatch repair(MMR)system.We found that the MMR gene mutL functions as a genetic switch through a slipped-strand mispairing mechanism,modulating and maintaining a dynamic balance between genetic stability and mutability during bacterial evolution.This mechanism allows bacteria to maintain their phylogenetic status,while also adapting to changing environments by acquiring novel traits.In this review,we outline the history of research into this genetic switch,from its discovery to the latest findings,and discuss its potential roles in the genomic evolution of bacteria.     

“In front of patients,I will always be a pupil.”Dr.Xiaoqian Zhang:the founder of the modern Chinese gastroenterology

Dr.Xiaoqian Zhang(张教骞,Hsiao-Chien Chang)was an outstanding clinician,therapist and medical educator,a member of the Academic Divisions of the Chinese Academy of Sciences,he is considered to be the founder of the modern Chinese gastroenterology(PUMCH,1988).As a doctor,he made a systemic and deep research on human blood volume,gastric secretion function,peptic ulcer disease,gastric ulcer and gastric cancer,celiac tuberculosis,amoebic dysentery,ulcerative colitis and so on.He diagnosed and treated multiple intractable diseases.As an educator,he emphasized the training of clinical basic skills,urged students to grasp the utilization of science in study and work.He trained a large number of talents for Chinese medicine.