Systematics of Mukdenia and Oresitrophe (Saxifragaceae): Insights from genome skimming data

Oresitrophe and Mukdenia (Saxifragaceae) are epilithic sister genera used in traditional Chinese medicine. The taxonomy of Mukdenia, especially of M. acanthifolia, has been controversial. To address this, we produced plastid and mitochondrial data using genome skimming for Mukdenia acanthifolia and Mukdenia rossii, including three individuals of each species. We assembled complete plastomes, mitochondrial CDS and nuclear ribosomal ETS/ITS sequences using these data. Comparative analysis shows that the plastomes of Mukdenia and Oresitrophe are relatively conservative in terms of genome size, structure, gene content, RNA editing sites and codon usage. Five plastid regions that represent hotspots of change (trnH-psbA, psbC-trnS, trnM-atpE, petA-psbJ and ccsA-ndhD) are identified within Mukdenia, and six regions (trnH-psbA, petN-psbM, trnM-atpE, rps16-trnQ, ycf1 and ndhF) contain a higher number of species-specific parsimony-informative sites that may serve as potential DNA barcodes for species identification. To infer phylogenetic relationships between Mukdenia and Oresitrophe, we combined our data with published data based on three different datasets. The monophyly of each species (Oresitrophe rupifraga, M. acanthifolia and M. rossii) and the inferred topology ((M. rossii, M. acanthifolia), O. rupifraga) are well supported in trees reconstructed using the complete plastome sequences, but M. acanthifolia and M. rossii did not form a separate clade in the trees based on ETS + ITS data, while the mitochondrial CDS trees are not well-resolved. We found low recovery of genes in the Angiosperms353 target enrichment panel from our unenriched genome skimming data. Hybridization or incomplete lineage sorting may be the cause of discordance between trees reconstructed from organellar and nuclear data. Considering its morphological distinctiveness and our molecular phylogenetic results, we strongly recommend that M. acanthifolia be treated as a distinct species.     

Vegetable biology and breeding in the genomics era

Vegetable crops provide a rich source of essential nutrients for humanity and represent critical economic values to global rural societies. However, genetic studies of vegetable crops have lagged behind major food crops, such as rice, wheat and maize, thereby limiting the application of molecular breeding. In the past decades, genome sequencing technologies have been increasingly applied in genetic studies and breeding of vegetables. In this review, we recapitulate recent progress on reference genome construction, population genomics and the exploitation of multi-omics datasets in vegetable crops. These advances have enabled an in-depth understanding of their domestication and evolution, and facilitated the genetic dissection of numerous agronomic traits, which jointly expedites the exploitation of state-of-the-art biotechnologies in vegetable breeding. We further provide perspectives of further directions for vegetable genomics and indicate how the ever-increasing omics data could accelerate genetic, biological studies and breeding in vegetable crops.

     

Differentiation of species in Gonioloboceras

The type specimen ofGonioloboceras goniolobum (Meek), rediscovered by Spath in the British Museum, is the foundation for a more accurate comparative study of this and other species ofGonioloboceras.Gonioloboceras described asG. goniolobum byElias in 1938 is differentiated asGonioloboceras schmidti, new species. Suture sets (new term) for several growth stages inG. goniolobum (Meek),G. welleriSmith,G. schmidtiElias, G.eliasiMiller &Owen, andG. asiaticumLibrovitch are assembled and used for differentiation of the species.The Kazakhstan goniatite faunule containingG. asiaticum is considered of very late Pennsylvanian age.     

生物成矿作用与生物矿化作用

列举５５种生物矿物，其中包括氧化物，含氧盐，水化物，羟基化物，钙化合物，指出它们通常经历非晶质、过渡、成熟和石化等４个相阶段。根据生物矿物体的元素丰度顺序与岩石圈和生物圈对比，将生矿元素分为６类。提出生矿元素保留于生物体内８种形式，即可溶无机化合物、有机络合物、生矿粒、生矿簇、骨针、骨片、骨壳和骨骼，并以磷为例阐明了生矿元素的富集过程。按照生物作用型式，建议划分生物矿床为堆积、粘结、吸附和储集４种成因类型，分别讨论它们成矿的生物、矿物和矿床，分析形成的环境、过程和阶段，并介绍中国某些著名生物矿床实例。最后总结了生物矿床的地史演化趋向：金属硫化物矿床→条带状硅铁（锰）粘结矿床→叠层状白云岩粘结矿床→磷酸盐和碳酸锰粘结矿床→铅锌和油气储集矿床→煤和油气。     

Factors Affecting Plant Regeneration from Tissue Cultures of Chinese Leymus (Leymus chinensis)

Chinese leymus (Leymus chinensis Trin.) is a perennial grass of the Gramineae, which is widely distributed in China, Mongolia and in Russian-Siberian. In order to explore the potential of biotechnology for genetic improvement of this forage grass, an efficient tissue culture system was established and the factors affecting plant regeneration were evaluated. Immature inflorescence segments 3–5 mm in length from eight accessions were cultured on N6 medium supplemented with 2.26–22.60 µM 2,4-D. The callus induction frequency ranged from 72.11 to 82.19%. Shoots were differentiated from the calli on N6 medium containing 4.65 µM kinetin and 4.44 µM BA. Viable regenerants were developed on hormone-free medium. Normal plants were obtained after natural vernalization in the field. The plant regeneration frequency in Chinese leymus was associated with different genotypes and different combinations of growth regulators in medium. The concentration of 2,4-D in the callus induction medium had a strong effect on successive plant regeneration. Relatively higher concentrations of 2,4-D (i.e., 9.04 and 22.60 µM) were more favorable to the plant regeneration than lower ones (i.e., 2.26 and 4.52 µM). This is the first report on plant regeneration in vitro in L. chinensis.     

Redescription of the Chengjiang arthropod Squamacula clypeata Hou and Bergström, from the Lower Cambrian, south-west China

The anatomy of the arthropod Squamacula clypeata Hou and Bergström, 1997 from the Lower Cambrian Chengjiang Lagersta¨tte is redescribed based on four newly excavated specimens. The new material was collected from localities recently discovered in the Kunming area, Yunnan Province, south-west China, and preserves remarkable details of the ventral morphology, revealed by preparation. Squamacula clypeata is dorsoventrally flattened and rounded in outline. The cephalon was covered by a wide, short shield, with a large doublure and a pair of uniramous antennae on the ventral side. The thorax consists of nine somites, each protected by a tergite and carrying at least one pair of biramous limbs. The pygidium is covered with a small rounded tergum. The endopod is segmented, equipped with short spines on the inner margin of the coxa and a claw-like structure distally, and the exopod flap-like, fringed with setae. The limbs in the pygidium are like those in the thorax in shape. Squamacula was most probably a nektobenthic predator. The spinose endopod could walk, grasp and grind. The large flap-like exopod was adapted for swimming and respiration. Its affinities lie with the Arachnomorpha, but the relationships with other known taxa remain ambiguous.     

Different effects on human skeletal myosin heavy chain isoform expression: strength vs. combination training.

Myosin heavy chain (MHC) isoform expression changes with physical training. This may be one of the mechanisms for muscular adaptation to exercise. We aimed to investigate the effects of different strength-training protocols on MHC isoform expression, bearing in mind that alpha- MHC(slow) (newly identified MHC isoform) mRNA may be upregulated in response to training. Twelve volunteers performed a 6-wk strength training with maximum contractions (Max group), and another 12 of similar age performed combination training of maximum contractions and ballistic and stretch-shortening movements (Combi group). Muscle samples were taken from triceps brachii before and after training. MHC isoform composition was determined by SDS-PAGE silver staining, and mRNA levels of MHC isoforms were determined by RT-PCR. In Max group, there was an increase in MHC(2A) (49.4 to 66.7%, P < 0.01) and a decrease in MHC(2X) (33.4 to 19.5%, P < 0.01) after training, although there was no significant change in MHC(slow). In Combi group, there was also an increase in MHC(2A) (47.7 to 62.7%, P < 0.05) and a decrease in MHC(slow) (18.2 to 9.2%, P < 0.05) but no significant change in MHC(2X). An upregulation of alpha-MHC(slow) mRNA was, therefore, found in both groups as a result of training. The strength training with maximum contractions led to a shift in MHC isoform composition from 2X to 2A, whereas the combined strength training produced an MHC isoform composition shift from slow to 2A.     

用gFM31探针进行谷子品种的指纹分析

用高度多态性探针ｇＦＭ３１对５９个谷子（ＳｅｔａｒｉａｉｔａｒｌｉｃａＢｅａｕｖ．）品种（包括地方品种、育成品种及品系）进行ＤＮＡ指纹分析,共鉴别出５８种类型,而黑谷和黑粒１５１６给出完全相同的带型,二者有可能是同一材料。通过对ｇＦＭ３１ＤＮＡ序列分析,未发现其中有小卫星ＤＮＡ和微卫星ＤＮＡ序列。该探针虽在谷子品种中显示很高的多态性,但与禾谷类的其他物种的ＤＮＡ杂交信号微弱,表现出较强的谷子基因组特异性。     

两种药用黄芪比较生物学研究

通过栽培实验,本文对两种药用黄芪的个体发育节律,根,茎,叶,花及种子的生物学特性进行了较系统的比较研究,为确定蒙古黄芪（ＡｓｔｒａｇａｌｕｓｍｏｎｇｈｏｌｉｃｕｓＢｕｎｇｅ）为独立的种,提供了更为全面的依据。