Copper porphyrins in deep-sea sediments: a possible indicator of oxidized terrestrial organic matter

Copper porphyrins have been isolated from deep-sea sediments collected during six legs of the Deep Sea Drilling Project-International Program of Ocean Drilling. These pigments are present in depositional areas receiving high inputs of terrestrially derived oxidized organic matter. Such areas include the Black Sea, the Bay of Biscay, the Blake-Bahama Basin, and slumped Miocene deposits off Cape Bojador on the west coast of Africa.     

Mediation of sulfur speciation by a black sea facultative anaerobe

Shewanella putrefaciens, a respiratory facultative anaerobe isolated from the Black Sea, can reduce thiosulfate, sulfite, and elemental sulfur to sulfide readily and quantitatively. This widespread and anaerobically versatile microorganism, which is incapable of reducing sulfate, uses oxidized sulfur intermediates as electron acceptors during the respiratory oxidation of organic matter. Because of its widespread distribution and abundance, it may play a significant role in sulfur and trace metal cycling in the Black Sea and in other marine and freshwater anaerobic environments.     

ARCHAELOGY: A Victim of the Black Sea Flood Found

Archaeologists are mulling over tantalizing images of what appears to have been a house of wood and mud littered with human artifacts now 91 meters beneath the Black Sea. The find lends further credence to the claims of two oceanographers that a torrent equaling 200 Niagara Falls cascaded from the Mediterranean Sea 7500 years ago, driving Neolithic peoples living along the Black Sea coastline inland. But whether the catastrophe gave rise to the biblical account of Noah's Flood and spread farming into central Europe, as the researchers speculate, we can't yet say.     

Black sea: recent sedimentary history

Three distinct sedimentary units, which can be correlated throughout the basin, occur in cores collected from the Black Sea. Carbon-14 ages help to define the recent sedimentary history of the Black Sea.     

Atlantic deep-sea stratigraphy: extension of absolute chronology to 320,000 years

Thorium-230 measurements on a core of globigerina ooze from the Caribbean Sea substantiate the prediction of Ericson et al. that the paleontological boundary U-V (Sangamon-Illinoian boundary in their scheme) in the Atlantic sediments has an age of close to 320,000 years. As the ages derived by Ericson et al. were based on extrapolations of mean sedimentation rates established by carbon-14 and protactinium-231 dating of the upper sections of this and other cores, this result confirms the assumption that sedimentation rates in the Caribbean Sea have not changed significantly during the past several hundred thousand years. The uranium content of the ocean as indicated by the deposition rate of thorium-230 was no more than 30 percent higher during glacial than during interglacial periods.     

The Beginnings of Metallurgy: A New Look: Arguments over diffusion and independent invention ignore the complex metallurgic crafts leading to iron

In the 9 years since my first survey of early metallurgy appeared in this journal (65) metallurgy has become a major battleground between those who argue independent invention and those who argue diffusion in the evolution of urban civilization. In this new article I contend that: 1) The upland belt and debouching river valleys of southwestern Asia have a clear priority in the beginnings of copper metallurgy and extractive metallurgy generally, suggesting that the forces of urbanization contributing to the rise of metallurgy there were more massive, widespread, and better integrated than elsewhere. 2) The trend to polymetallism, against the background of pyrotechnology generally and the other important technologies of urbanism, established a necessary sequence to early metallurgy. This sequence was a prerequisite to the coming of the Iron Age, which was uniquely contained at first within the environment of Anatolia and the eastern Mediterranean and spread outward from there. 3) The course of metallurgy and possibly of the other urbanizing technologies can best be understood through a process of diffusion and multiple innovation interrelating metallurgical evolution over much of Eurasia, but with the area defined by the Black Sea, the Caspian Sea, the Red Sea, and the eastern Mediterranean as its center. Only in this fashion can we place metallurgy in its proper role as an important subsystem in the rise of civilization.     

Local interactions select for lower pathogen infectivity

Theory suggests that the current rapid increase in connectivity and consequential changes in the structure of human, agricultural, and wildlife populations may select for parasite strains with higher infectivity. We carried out a test of this spatial theory by experimentally altering individual host movement rates in a model host/pathogen system by altering the viscosity of their environment. In our microevolutionary selection experiments, the infectivity of the virus was, as predicted by the theory, reduced in the most viscous populations. We therefore provide empirical support for the theory that population structure affects the evolution of infectious organisms.     

Mass mortality and its environmental and evolutionary consequences

The latest Mesozoic and earliest Tertiary sediments at Deep Sea Drilling Project site 524 provide an amplified record of environmental and biostratographic changes at the end of Cretaceous. Closely spaced samples, representing time intervals as short as 10(2) or 10(3) years, were analyzed for their bulk carbonate and trace-metal compositions, and for oxygen and carbon isotopic compositions. The data indicate that at the end of Cretaceous, when a high proportion of the ocean's planktic organisms were eliminated, an associated reduction in productivity led to a partial transfer of dissolved carbon dioxide from the oceans to the atmosphere. This resulted in a large increase of the atmospheric carbon dioxide during the next 50,000 years, which is believed to have caused a temperature rise revealed by the oxygen-isotope data. The lowermost Tertiary sediments at site 524 include fossils with Cretaceous affinities, which may include both reworked individuals and some forms that survived for a while after the catastrophe. Our data indicate that many of the Cretaceous pelagic organisms became extinct over a period of a few tens of thousands of years, and do not contradict the scenario of cometary impact as a cause of mass mortality in the oceans, as suggested by an iridium anomaly at the Cretaceous-Tertiary boundary.     

稻瘟病菌在中国鉴别品种及CO39近等基因系上的致病型分析

稻瘟病是影响水稻高产、稳产的主要病害之一,在中国的大多数稻区都有发生.崇阳、远安是湖北省稻瘟病常发区,在两地采集稻瘟病穗颈瘟标本,从中分离得到60个稻瘟病菌单孢菌株(崇阳、远安两地的菌株各30个),分别在中国鉴别品种和CO39近等基因系上进行致病型鏊定,发现60个单孢菌株接种于CO39近等基因系6个品种上,在可能的26个致病类型中出现了20种,小种丰富度为2.54,优势类型为I 37.1.相同的60个单孢菌株在中国鉴别品种上出现4群13个小种,小种丰富度1.22,优势种群与前几年的一致,均为ZA群.     

Multiple Ebola virus transmission events and rapid decline of central African wildlife

Several human and animal Ebola outbreaks have occurred over the past 4 years in Gabon and the Republic of Congo. The human outbreaks consisted of multiple simultaneous epidemics caused by different viral strains, and each epidemic resulted from the handling of a distinct gorilla, chimpanzee, or duiker carcass. These animal populations declined markedly during human Ebola outbreaks, apparently as a result of Ebola infection. Recovered carcasses were infected by a variety of Ebola strains, suggesting that Ebola outbreaks in great apes result from multiple virus introductions from the natural host. Surveillance of animal mortality may help to predict and prevent human Ebola outbreaks.     

Fantasy and reality: The black farmer's place in American agriculture

The shared hopes of farm ownership in America motivated many Black farmers and educators during the nineteenth and early twentieth centuries. Although an independent Black yeomanry was not to be, and a host of factors have combined to remove Black Americans from farming, the quest has not been a vain one. Black land-grant institutions continue to redefine their mission in a changing world and in the process maintain their relevancy.     

Abrupt tropical vegetation response to rapid climate changes

Identifying leads and lags between high- and low-latitude abrupt climate shifts is needed to understand where and how such events were triggered. Vascular plant biomarkers preserved in Cariaco basin sediments reveal rapid vegetation changes in northern South America during the last deglaciation, 15,000 to 10,000 years ago. Comparing the biomarker records to climate proxies from the same sediment core provides a precise measure of the relative timing of changes in different regions. Abrupt deglacial climate shifts in tropical and high-latitude North Atlantic regions were synchronous, whereas changes in tropical vegetation consistently lagged climate shifts by several decades.     

东海北部外海剑尖枪乌贼渔业生物学特征

根据2017和2018年的9月—翌年2月拖网渔船在东海北部外海采集的剑尖枪乌贼样本,研究其基础生物学特征。结果表明,个体的优势胴长和体质量组雄性分别为100～180 mm和40～160 g(n=309尾),雌性分别为80～160 mm和40～160 g(n=304尾),雌雄个体的胴长和体质量年间不存在差异。协方差分析(ANCOVA)表明,雄性个体体质量-胴长关系年间差异显著(P0.05),而雌性年间差异不显著(P0.05)。性成熟胴长雄性主要集中在大于120 mm的个体,雌性为大于140 mm的个体,并且呈现出较小体型下即可达到性腺成熟的趋势。雌性个体的胴长和体质量生长速率略快于雄性,并且雌雄个体的体质量生长率年间差异较大。综合分析认为:两年间采样的剑尖枪乌贼种群为春季和夏季产卵种群,2018年样本中夏季产卵种群的幼体数量较多。因此,研究剑尖枪乌贼渔业生物学动态特征是资源持续开发和渔业管理的基础。     

El Niño-like pattern in ice age tropical Pacific sea surface temperature

Sea surface temperatures (SSTs) in the cold tongue of the eastern equatorial Pacific exert powerful controls on global atmospheric circulation patterns. We examined climate variability in this region from the Last Glacial Maximum (LGM) to the present, using a SST record reconstructed from magnesium/calcium ratios in foraminifera from sea-floor sediments near the Galápagos Islands. Cold-tongue SST varied coherently with precession-induced changes in seasonality during the past 30,000 years. Observed LGM cooling of just 1.2 degrees C implies a relaxation of tropical temperature gradients, weakened Hadley and Walker circulation, southward shift of the Intertropical Convergence Zone, and a persistent El Ni?o-like pattern in the tropical Pacific. This is contrasted with mid-Holocene cooling suggestive of a La Ni?a-like pattern with enhanced SST gradients and strengthened trade winds. Our results support a potent role for altered tropical Pacific SST gradients in global climate variations.     

Atlantic water flow pathways revealed by lead contamination in Arctic basin sediments

Contaminant lead in sediments underlying boundary currents in the Arctic Ocean provides an image of current organization and stability during the past 50 years. The sediment distributions of lead, stable lead isotope ratios, and lead-210 in the major Arctic Ocean basins reveal close coupling of the Eurasian Basin with the North Atlantic during the 20th century. They indicate that the Atlantic water boundary current in the Eurasian Basin has been a prominent pathway, that contaminant lead from the Laptev Sea supplies surface water in the transpolar drift, and that the Canadian and Eurasian basins have been historically decoupled.     

介导植物病毒病症状发生的病毒元件与寄主因子

植物遭受病毒侵染后,常表现出花叶、发育畸形、褪绿、坏死等症状。在农业生产中,这些症状的发生直接导致作物的产量/品质下降,有些造成严重的经济损失。因而,病毒病症状发生的分子机制长期以来一直为人们所关注。本文结合近年来国内外最新的研究报道,分别从病毒和寄主两个方面,总结归纳了介导症状发生的病毒元件以及参与症状发生的寄主因子,并在此基础上分析讨论了病毒病症状发生的分子机制。     

A novel mode of arbovirus transmission involving a nonviremic host

In nature, infected and uninfected arthropod vectors often feed together on an animal. In mimicking this scenario in the laboratory, uninfected vectors were found to acquire virus while cofeeding on the same host as infected vectors. However, the vertebrate host on which they fed did not develop detectable levels of virus in its blood. These observations were made with Thogoto virus, an influenza-like virus of medical and veterinary significance. Rhipicephalus appendiculatus ticks were used as the vector and guinea pigs as the vertebrate host. The results demonstrate that a vertebrate that is apparently refractory to infection by an arthropod-borne virus can still play an important role in the epidemiology of the virus, and they suggest a novel mode of arthropod-borne virus transmission.     

Cloned Cauliflower Mosaic Virus DNA Infects Turnips (Brassica rapa)

Cauliflower mosaic virus DNA cloned in the Sal I site of bacterial plasmid pBR322 infects turnip plants. The cloned viral DNA must be excised from the recombinant plasmid to infect, but need not be circularized and ligated in vitro. The cloned viral DNA lacks site-specific single-strand breaks found in DNA obtained directly from the virus. However, these breaks are reintroduced into the viral genome during multiplication of the virus in the plant host.     

Transmission of vesicular stomatitis virus from infected to noninfected black flies co-feeding on nonviremic deer mice

Vesicular stomatitis is an economically important arboviral disease of livestock. Viremia is absent in infected mammalian hosts, and the mechanism by which insects become infected with the causative agents, vesicular stomatitis viruses, remains unknown. Because infected and noninfected insects potentially feed on the same host in nature, infected and noninfected black flies were allowed to feed on the same host. Viremia was not detected in the host after infection by a black fly bite, but because noninfected black flies acquired the virus while co-feeding on the same host with infected black flies, it is concluded that a viremic host is not necessary for an insect to be infected with the virus. Thus co-feeding is a mechanism of infection for an insect-transmitted virus.     

Advances in Research of Garlic Virus Diseases

Garlic virus infection is an important disease which affects garlic production,with the increasing years of planting,harm of virus is serious year by year,which seriously affect yield and quality of garlic.In order to know the garlic virus effectively,the paper reviewed the research situation of several important garlic virus in virus species,origin,distribution,host range,symptom,route of transmission,classification,genome and detection technique and the prevention technology of garlic viruses.At the same ...