Plant chemistry and the evolution of host specificity: new evidence from heliconius and passiflora

Larval growth rates of Heliconius butterflies do not closely parallel host plant choice, an indication that factors other than host plant chemistry are important in evolving host specificity. High growth rate in one species is correlated with reduction in number of palatable host species. This suggests a mechanism by which ecologically restricted species become progressively biochemically specialized.     

Lunar surface chemistry: a new imaging technique

Detailed chemical maps of the lunar surface have been constructed by applying a new weighted-filter imaging technique to Apollo 15 and Apollo 16 x-ray fluorescence data. The data quality improvement is amply demonstrated by (i) modes in the frequency distribution, representing highland and mare soil suites, which are not evident before data filtering and (ii) numerous examples of chemical variations which are correlated with small-scale (about 15 kilometer) lunar topographic features.     

Infectious nucleic acids,a new dimension in virology

Viral nucleic acids have been found to be infectious for tissues and animals, yet are nonantigenic and resistant to antibodies against whole virus. Other unique properties, such as their host range and their susceptibility to nuclease action, render them a wholly new dimension to be reckoned with in virology. These properties may explain a number of conditions which at present are considered anomalous. The release from infected tissues of even a small proportion of total virus as free nucleic acid could, in an otherwise immune individual, lead to a low level of infection which would, perhaps, explain permanent immunity. If the proportion of nucleic acid is higher, or if the nucleic acid is resistant to nucleases because of an inert envelope, such conditions as "carrier" states-that is, viremias with or without antibodies-are possible. Note added in proof: The recent article by J. D. Ebert and F. H. Wilt (54) came to my attention after the present article was written. Ebert and Wilt's excellent article indicates the impact of the newer knowledge of viral nucleic acids on the ideas developing in the field of embryology.     

Monilinia fructicola on loquat: An old pathogen invading a new host

Monilinia fructicola has been widely reported as the causal agent of brown rot disease on many Rosaceae family fruits worldwide. It has been reported on stone fruits, e.g., peach, plum, cherry, apricot and mume; as well as pome fruits, e.g., apple, pear and hawthorn. Loquat is a member of the Eriobotrya genus in subfamily Maloideae along with apple, pear and hawthorn. So far, loquat has not been reported as the host of any Monilia species. In June 2019, brown rot symptoms were observed on loquat fruits in an orchard in Wuhan, Hubei Province, China. Thirty single spore isolates were obtained and identified as M. fructicola based on morphological characteristics and molecular analysis. This is the first report of loquat brown rot disease caused by Monilia species in the world. Furthermore, upon artificial inoculation, all three Monilia species from peach in China, i.e., M. fructicola, M. mumecola and M. yunnanensis, could cause typical brown rot disease on loquat fruits. At the same time, M. fructicola isolates from loquat showed virulence similar to those isolates from peach when the pathogenicity test was conducted on peach fruits. These results suggested that loquat could be infected by other Monilia species and that isolates from loquat also have potential to damage other Rosaceae family fruits in practice.     

壳聚糖衍生物阻垢缓蚀的量子化学研究

针对线型高分子具有重复单元的结构特点,提出一种优化算法.以壳聚糖(CTS)和羧甲基壳聚糖(CM-CTS)为例,利用GaussView 6.0软件对两种分子进行了量子化学计算,对其分子结构、前线轨道能级、电子云密度、原子电荷分布、作用基团空间密度和链柔性进行分析,初步探讨了它们的阻垢缓蚀性能.计算结果表明,CTS和CM-...     

头状茎点霉病菌的新寄主高粱及病菌的检疫鉴定

从进境美国高粱种子中分离到1种真菌,通过用不同培养基培养,观察菌落特征及病原菌形态特征,进行形态学鉴定;并结合分子生物学方法选取了目前常用的能够用于对Phoma属不同种进行区分的4个基因片段ITS、TUB、ACT和TEF进行PCR扩增、产物序列测定及比对分析,同时应用柯赫氏法则进行致病性测定,结果均表明该真菌为头状茎点霉病菌Phoma glomerata。此病原真菌在高粱上发现属于首次报道。该病菌是我国进境植物检疫性有害生物,寄主范围十分广泛,但在高粱中未发现有为害的报道,此次检出可判定高粱为该病菌的世界新寄主。     

Solid-state chemistry: a a rediscovered chemical frontier

Chemical bonding in solids is not completely understood, mainly because of the wide variation in the chemical properties of the elements. Many difficult challenges remain in predicting the composition, structure, and the properties of new materials. Consequently, the synthesis of novel solids is as much an art as a science. Discoveries of new compounds and structure types highlight the versatility that nature has allowed with the relatively small number of elements. This article explores the long-term challenges in solid-state chemistry and then focuses on efforts at Cornell to prepare new solids.     

Geminga's tails: a pulsar bow shock probing the interstellar medium

We report the X-ray Multimirror Mission-Newton European Photon Imaging Camera observation of two elongated parallel x-ray tails trailing the pulsar Geminga. They are aligned with the object's supersonic motion, extend for approximately 2', and have a nonthermal spectrum produced by electron-synchrotron emission in the bow shock between the pulsar wind and the surrounding medium. Electron lifetime against synchrotron cooling matches the source transit time over the x-ray features' length. Such an x-ray detection of a pulsar bow shock (with no Halpha emission) allows us to gauge the pulsar electron injection energy and the shock magnetic field while constraining the angle of Geminga's motion and the local matter density.     

Pathogenesis of a local graft versus host reaction: immunogenicity of circulating host leukocytes

A local invasive-destructive reaction typical of that seen in allograft rejection occurs when Lewis rat spleen cells are inoculated under the capsule of Lewis kidney freshly grafted into F(1) hybrid hosts. Thus the donor lymphoid cells can be immunogenically stimulated by circulating host leukocytes and the interaction of these two cell populations results in nonspecific damage to kidney parenchyma. The results indicate that passenger leukocytes in organ allografts may be important immunogenic agents.     

Methylene: a paradigm for computational quantum chemistry

The year 1970 has been suggested as a starting date for the "third age of quantum chemistry," in which theory takes on not only qualitative but also quantitative value. In fact, each of the years 1960, 1970, 1972, and 1977 is of historical value in the unraveling of the structure and energetics of the CH(2) molecule, methylene. What took place for methylene, namely the establishment of credibility for theory, has subsequently taken place for many other molecules. Three important roles for quantitative theory are outlined: (i) theory precedes experiment; (ii) theory overturns experiment, as resolved by later experiments; and (iii) theory and experiment work together to gain insight that is afforded independently to neither. Several examples from each of the three classes are given.