Tobamovirus and Potyvirus Accumulation in Minor Veins of Inoculated Leaves from Representatives of the Solanaceae and Fabaceae1

Virus invasion of minor veins in inoculated leaves of a host is the likely prelude to systemic movement of the pathogen and to subsequent yield reduction and quality loss. In this study we have analyzed the cell number and arrangement in minor veins within mature leaves of various members of the Solanaceae and Fabaceae families. We then monitored the accumulation pattern of several tobamoviruses and potyviruses in these veins at the time of rapid, phloem-mediated movement of viruses. Vascular parenchyma cells were the predominant and sometimes only cells to become visibly infected among the cells surrounding the sieve elements in minor veins containing 9 to 12 cells. In no instance did we observe a companion cell infected without a vascular parenchyma cell also being infected in the same vein. This suggests that the viruses used in this study first enter the vascular parenchyma cells and then the companion cells during invasion. The lack of detectable infection of smooth-walled companion or transfer cells, respectively, from inoculated leaves of bean (Phaseolus vulgaris) and pea (Pisum sativum) during a period of known rapid, phloem-mediated movement suggests that some viruses may be able to circumvent these cells in establishing phloem-mediated infection. The cause of the barrier to virus accumulation in the companion or transfer cells, the relationship of this barrier to previously identified barriers for virus or photoassimilate transport, and the relevance of these findings to photoassimilate transport models are discussed.

Invasion of minor veins of tobacco leaves inoculated with tobacco mosaic virus mutants defective in phloem-dependent movement.

To fully understand vascular transport of plant viruses, the viral and host proteins, their structures and functions, and the specific vascular cells in which these factors function must be determined. We report here on the ability of various cDNA-derived coat protein (CP) mutants of tobacco mosaic virus (TMV) to invade vascular cells in minor veins of Nicotiana tabacum L. cv. Xanthi nn. The mutant viruses we studied, TMV CP-O, U1mCP15-17, and SNC015, respectively, encode a CP from a different tobamovirus (i.e., from odontoglossum ringspot virus) resulting in the formation of non-native capsids, a mutant CP that accumulates in aggregates but does not encapsidate the viral RNA, or no CP. TMV CP-O is impaired in phloem-dependent movement, whereas U1mCP15-17 and SNC015 do not accumulate by phloem-dependent movement. In developmentally-defined studies using immunocytochemical analyses we determined that all of these mutants invaded vascular parenchyma cells within minor veins in inoculated leaves. In addition, we determined that the CPs of TMV CP-O and U1mCP15-17 were present in companion (C) cells of minor veins in inoculated leaves, although more rarely than CP of wild-type virus. These results indicate that the movement of TMV into minor veins does not require the CP, and an encapsidation-competent CP is not required for, but may increase the efficiency of, movement into the conducting complex of the phloem (i.e., the C cell/sieve element complex). Also, a host factor(s) functions at or beyond the C cell/sieve element interface with other cells to allow efficient phloem-dependent accumulation of TMV CP-O.

Isotope characterization and estimated temperature of formation of calcite veins in ODP Sites 124-768 and 124-770 (Table 1)

Secondary carbonate minerals were recovered within the basalts at both ODP Sites 768 and 770 in the Sulu and Celebes seas. Petrographic and X-ray diffraction analyses indicate that the carbonates are calcites. Other alteration products recognized in the thin sections are smectites, iron oxides, and gypsum. The 13C values of carbonates from both sites range from 1.6 per mil to 2.3 per mil, which are indicative of inorganic carbonate formation with no contributions from 13C-depleted sources such as oxidized organic carbon or methane. The oxygen isotopes at Site 770 range from 30.8 per mil to 31.6 per mil, which indicates a pervasive circulation of cold seawater (9° to 12°C) during alteration of the Celebes Sea basalts. In contrast, carbonates associated with Site 768 basalts have less positive d18O values (21.0 per mil to 27.3 per mil). A lighter 18O isotopic signature indicates the formation of secondary calcite at either higher temperatures or in a system closed to seawater. The rapidly deposited pyroclastic flows at Site 768 would have limited water access to the crust very soon after its formation, which leads us to speculate that the carbonates in the Sulu Sea basalts were formed by isotopically modified fluids resulting from basalt alteration in a closed system.

On the origin of the lymphatic system from the veins and the development of the lymph hearts and thoracic duct in the pig /

Offprint: American journal of anatomy. Vol. 1, no. 3 (May 26, 1902).

Boylston medical prize dissertations for the years 1819 and 1821. Experiments and observations on the communication between the stomach and the urinary organs, and on the propriety of administering medicine by injection into the veins.

Dissertation I. On the question, Is there any communication from the stomach to the bladder, more direct than that through the circulating system and the kidneys? Which obtained the Boylston premium in 1819.--Dissertation II. On the question, Can medicinal substances be safely and advantageously introduced into animal bodies through the medium of the veins? Which obtained the Boylston premium in 1821.

Pocket geologist and book of minerals. Elements, minerals, rocks, veins, metals, ores, carbons, gems, spars, limes, clays, grits, salts, paints.

Mode of access: Internet.