Cyclaster danicus, a shallow burrowing non-marsupiate echinoid

The spatangoid Cyclaster danicus has been placed in the genus Brissopneustes by previous authors. The material from the Lower Danian of Denmark includes some abnormal individuals with depressed apical area. These have been previously interpreted as females with a marsupium. A study of both normal and abnormal tests indicates that the depressed apical area is not a marsupium but rather a malformation, possibly caused by adverse environmental conditions or by a parasite. The skeletal morphology indicates that C. danicus was a shallow burrowing form but the malformed individuals probably did not burrow.     

BRACHIOPOD PALAEOECOLOGY IN MIDDLE DANIAN LIMESTONES AT FAKSE, DENMARK

The Danian limestone in the Fakse quarry displays banks of coral limestone interfingering with banks of bryozoan limestone. (1) Previous and present studies on the brachiopods show that ‘Rhynchonella’ flustracea Buch, ‘R.’ faxensis Posselt, ‘Terebratula’ mobergi Lundgren, and Argyrotheca pindborgi (Nielsen) are restricted to the coral limestone of Fakse. (2) Crania (Danocrania) transversa (Lundgren), C. (D.) tuberculata (Nilsson), Isocrania aff. egnabergensis (Retzius), ‘Terebratula’ fallax Lundgren, and Carneithyris incisa (Buch) are known from bryozoan limestone at Fakse and other Middle Danian localities. (3) Common to both kinds of sediments in Fakse quarry and found at other Middle Danian bryozoan limestone localities as well are Terebratulina aff. chrysalis (Schlotheim), Argyrotheca scabricula (Koenen), Megathiris bruennichi (Rosenkrantz), Platidia sp., and Thecidellina? groenwalli (Nielsen). (4) ‘Terebratula cincta’ Nielsen is restricted to Fakse quarry and occurs in both kinds of sediments. (5) Some of the species restricted to the coral limestone appear to be morphologically adapted to fit in between the branches of the dominant coral in Fakse quarry, Dendrophyllia candelabrum Hennig.     

A chemotaxonomic investigation of Thapsia villosa L., Apiaceae (Umbelliferae)

Chemotaxonomic investigations of Thapsia villosa L., Apiaceae, have resulted in a division of the species into five different types, representing two distinctly different groups. Thapsigargins, the guaianolide sesquiterpene lactones with unique bioactivity, are present only in one of these groups, which includes two morphologically identical types, with different chromosome numbers, 2 n =44 [4×] and 2 n =66 [6×]. Besides thapsigargins, 6-methoxy-7-geranyloxycoumarin and phenylpropanoids are characteristic constituents of the roots, and limonene and methyl eugenol are the two major constituents of the fruit essential oil. The other group with clearly different morphological characters includes three types with the chromosome numbers 2 n =22 [x], 2 n =22 [2×] and 2 n =44 [4×]. Different sesquiterpenes are the characteristic constituents of their roots, tovarol and hydroindene derivatives being present in all three types, whereas guaiane esters have been detected in only one of the diploid types. Geranyl acetate is the major constituent of the fruit essential oil of all three types within this group.     

Comparative studies in phytochemistry and fruit anatomy of Thapsia garganica and T. transtagana,Apiaceae (Umbelliferae)

Thapsia garganica L. and T. transtagana Brot. are classified as synonymous in Flora Europaea. In the present investigation significant differences between the two taxa with regard to fruit anatomy and phytochemistry are demonstrated and they are considered as two separate species. Microscopic studies revealed a distinct difference in number and position of secretory spaces in the pericarp of fruits from the two species and in addition pronounced differences were found in the presence of thapsigargins, the bioactive constituents of the two species. Quantitative HPLC analyses of thapsigargins were carried out on different plant organs from T. garganica and T. transtagana collected from various locations. Thapsigargin, thapsigargicin, nortrilobolid and thapsivillosin I and J were dominant compounds in all organs of T. garganica whereas none of these compounds could be detected in any organ of T. transtagana. On the contrary, thapsitranstagin and trilobolid were main thapsigargins of T. transtagana. T. garganica may include two chemotypes, as trilobolid was detected in some specimens of T. garganica only. As this is the first time trilobolid has been detected in these two species, it was isolated from both and identified by ¹H NMR-spectroscopy.     

Pheomelanin as a Binding Site for Drugs and Chemicals

Certain drugs and chemicals, such as chloroquine, chlorpromazine, and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), are bound to melanin and retained in pigment cells for long periods. This specific retention in pigmented tissues can cause adverse effects in the skin, eye, inner ear, and pigmented nerve cells of the substantia nigra of the brain. To date, all studies have been focused on eu- and neuromelanin. In the present study, we show that chloroquine, chlorpromazine, chlomipramine, paraquat, acridine orange, and nickel, which are bound to eumelanin, also bind to synthetic pheomelanin, but the binding to pheomelanin is lower. The binding varied with the cysteine content and pH, and the results indicate that the binding is complex and includes ionic interactions. In addition, we have shown that these substances also bind to synthetic thiourea-containing melanin, but to quite a low extent. We also present a microautoradiographic study on the binding of ¹⁴C-chloroquine to natural pheomelanin in vivo in yellow mice C57BL (A^y/a). Black (C57/BL) and albino (NMRI) mice were used as controls. The autoradiography demonstrated a pronounced uptake of chloroquine in the hair follicles and the dermal melanocytes in the ear of yellow mice, which was comparable to the corresponding accumulation of label in black mice. In the albino mouse, the uptake was lower and more homogeneously distributed in the skin. These results suggest that the toxicologi-cal risks of melanin-related adverse effects are applicable to persons with a high content of pheomelanin in the skin and hair.     

Visualization of novel virulence activities of the Xanthomonas type III effectors AvrBs1, AvrBs3 and AvrBs4

Xanthomonas campestris pv. vesicatoria secretes at least 20 effector proteins through the type III secretion system directly into plant cells. In this study, we uncovered virulence activities of the effector proteins AvrBs1, AvrBs3 and AvrBs4 using Agrobacterium‐mediated transient expression of the corresponding genes in Nicotiana benthamiana, followed by microscopic analyses. We showed that, in addition to the nuclear‐localized AvrBs3, the effector AvrBs1, which localizes to the plant cell cytoplasm, also induces a morphological change in mesophyll cells. Comparative analyses revealed that avrBs3‐expressing plant cells contain highly active nuclei. Furthermore, plant cells expressing avrBs3 or avrBs1 show a decrease in the starch content in chloroplasts and an increased number of vesicles, indicating an enlargement of the central vacuole and the cell wall. Both AvrBs1 and AvrBs3 cause an increased ion efflux when expressed in N. benthamiana. By contrast, expression of the avrBs3 homologue avrBs4 leads to large catalase crystals in peroxisomes, suggesting a possible virulence function of AvrBs4 in the suppression of the plant defence responses. Taken together, our data show that microscopic inspection can uncover subtle and novel virulence activities of type III effector proteins.     

New Thioureas and Related Substances Intended for Melanoma Targeting

Thiouracil and a few related drugs are known to be melanoma-seeking agents owing to specific incorporation into nascent melanin. The melanin-affinic properties are apparently due to binding to intermediates, preferably dopaquinone, produced in the melanin synthetic pathway by tyrosinase-catalysed oxidation of tyrosine. In the present paper, in vitro screening methods have been used for the identification of possible melanoma seekers according to the above principle. The binding of test substance to dopaquinone suppresses dopachrome formation by the withdrawal of dopaquinone from the reaction mixture, and the decrease in dopachrome concentration was monitored spectrophotometrically at 475 nm. In order to eliminate false results caused by tyrosinase inhibition, which also will decrease the dopachrome concentration, the oxygen consumption was followed potentiometrically. To avoid the effect of tyrosinase inhibition on dopachrome formation, additional experiments with autoxidation of L-dopa in the presence of test substance were performed. Of the 22 substances (mainly thioureylenes and thioamides) studied, 4,5,6-triamino-2(H)-pyrimidinehtionsulfate, trithiocyanuric acid, 2-thiouracil, 6-methyl-2-thiouracil, and 4-amino-2-mercaptopyrimidine most effectively decreased the dopachrome formation with no or little inhibition of tyrosinase activity. They should therefore be regarded as potential melanoma seekers. In a complementary autoradiographic study on the uptake of the potent tyrosinase inhibitor mercaptobenzothiazole (MBT) in B 16 melanoma, transplanted to mice, it was found that strong tyrosinase inhibition seems to decrease incorporation into melanin in vivo. MBT was partly accumulated in restricted areas of the tumor, which may be explained by the small molar dose injected.