Dimeric DOTA-α-Melanocyte-Stimulating Hormone Analogs: Synthesis and In Vivo Characteristics of Radiopeptides with High In Vitro Activity

Dimeric analogs of α-melanocyte-stimulating hormone (α-MSH) labeled with radiometals are potential candidates for diagnosis and therapy of melanoma by receptor-mediated tumor targeting. Both melanotic and amelanotic melanomas (over-)express the melanocortin-1 receptor (MC1-R), the target for α-MSH. In the past, dimerized MSH analogs have been shown to display increased receptor affinity compared to monomeric MSH, offering the possibility of improving the ratio between specific uptake of radiolabeled α-MSH by melanoma and nonspecific uptake by the kidneys. We have designed three linear dimeric analogs containing a slightly modified MSH hexapeptide core sequence (Nle-Asp-His-d-Phe-Arg-Trp) in parallel or antiparallel orientation, a short spacer, and the DOTA chelator for incorporation of the radiometal. In vitro, all three peptides were more potent ligands of the mouse B16-F1 melanoma cell melanocortin-1 receptor (MC1-R) than DOTA-NAPamide, which served as standard. The binding activity of DOTA-diHexa(NC-NC)-amide was 1.75-fold higher, that of diHexa(NC-NC)-Gly-Lys(DOTA)-amide was 3.37-fold higher, and that of DOTA-diHexa(CN-NC)-amide was 2.34-fold higher. Using human HBL melanoma cells, the binding activity of diHexa(NC-NC)-Gly-Lys(DOTA)-amide was sixfold higher than that of DOTA-NAPamide. Uptake by cultured B16-F1 cells was rapid and almost quantitative. In vivo, however, the data were less promising: tumor-to-kidney ratios 4 hr postinjection were 0.11 for [¹¹¹In]DOTA-diHexa(NC-NC)-amide, 0.26 for diHexa(NC-NC)-Gly-Lys([¹¹¹In]DOTA)-amide, and 0.36 for [¹¹¹In]DOTA-diHexa(CN-NC)-amide, compared to 1.67 for [¹¹¹In]DOTA-NAPamide. It appears that despite the higher affinity to the MC1-R of the peptide dimers and their excellent internalization in vitro, the uptake by melanoma tumors in vivo was lower, possibly because of reduced tissue penetration. More striking, however, was the marked increase of kidney uptake of the dimers, explaining the unfavorable ratios. In conclusion, although radiolabeled α-MSH dimer peptides display excellent receptor affinity and internalization, they are no alternative to the monomeric DOTA-NAPamide for in vivo application.     

NO signalling in cytokinin-induced programmed cell death

Cell death can be induced by cytokinin 6-benzylaminopurine (BA) at high dosage in suspension-cultured Arabidopsis cells. Herein, we provide evidence that BA induces nitric oxide (NO) synthesis in a dose-dependent manner. A reduction in cell death can be observed when the cytokinin is supplemented with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) or the nitric oxide synthase (NOS) inhibitors: 2-aminoethyl-isothiourea (AET) and N^G.-monomethyl- l -arginine ( l -NMMA), which suggests that NO is produced via a NOS and is a signalling component of this form of programmed cell death. In BA-treated cells, mitochondrial functionality is altered via inhibition of respiration. This inhibition can be prevented by addition of either cPTIO or AET implying that NO acts at the mitochondrial level.     

Terrestrial Passive Integrated Transponder Antennae for Tracking Small Animal Movements

ABSTRACT Measuring terrestrial movements of small animals poses a substantial technological challenge. We developed very long (up to 130 m) passive integrated transponder (PIT) detectors with which we tracked salamanders (Caudata) migrating from breeding ponds to their upland habitat >200 m away. In all 60 trials, salamanders were detected when released near the antennae. In a second test, we tracked 7 of 14 tagged marbled salamanders (Ambystoma opacum) migrating >65 m, well beyond the area protected by existing wetland buffer regulations in Massachusetts, USA. The mean rate of movement for these salamanders (x̄ = 0.9 m/min; SE = 0.1 m/min) was substantially higher than rates of movement reported for related salamanders with radio-implants. These PIT antennae offer researchers a means to study small animal movements with less disruption of the animals’ natural movement patterns than is caused by other available techniques.     

Adaptive spatiotemporal distribution of soil microfungi in 'Evolution Canyon' II, Lower Nahal Keziv, western Upper Galilee, Israel

We describe and interpret spatiotemporal micromycete community structure and adaptive complexes in contrasting xeric and mesic microclimates in the soils of 'Evolution Canyon' II, Lower Nahal Keziv, western Upper Galilee, Israel. A total of 192 species from 60 genera belonging to Zygomycota (nine species), Ascomycota (13 species), and mitosporic fungi (170 species) were isolated. The fungal communities on the south-facing, xeric, 'African' slope (AS) demonstrated significantly greater diversity than on the north-facing, mesic, 'European' slope (ES) and the valley bottom (VB). Seasonally, winter slope communities were less heterogeneous. Forest localities on the ES and the VB in all seasons and the shady localities on the AS in the winter were overwhelmingly dominated by mesophilic Penicillium species. The sunny locality on the AS was characterized by a dominance of melanin-containing micromycetes that was most pronounced in the summer and by high occurrence and abundance of thermotolerant and thermophilic Aspergillus and Fusarium species. Ascomycetes and zygomycetes were the minor components in all local mycobiota studied; sexual ascomycetes, being stress-selected fungi, were more than ten times more abundant in the soil of the AS than in that of the ES, with the peak of abundance in the sunny summer community. The results demonstrated a microscale adaptive spatiotemporal inter- and intraslope divergence in soil mycobiota structure. Microclimatic natural selection appears to be the major factor affecting soil fungus diversity patterns.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78, 527–539.     

Hymenaea mexicana sp. nov. (Leguminosae: Caesalpinioideae) from Mexican amber indicates Old World connections

Hymenaea mexicana sp. nov. is described in amber originating from mines of Chiapas, Mexico. The species is characterized by clawed showy petals with cordate bases and glabrous, verrucose ovaries with long hirsute hairs at their bases and margins on one side. This species is closely related to the extinct Hymenaea protera from Dominican amber, and together with it, is placed in the primitive section Trachylobium of the genus Hymenaea in the caesalpinoid legumes. The closest extant species to H. mexicana is H. verrucosa , a relict surviving in East Africa. These results challenge previous views that Mexican amber was produced by the South American species H. courbaril – H. intermedia , which belong to the advanced section of the genus.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 125–132.     

Cytoevolution, Phylogeny and Taxonomy in Epacridaceae

Chromosome numbers in Epacridaceae were collated from variousauthors and superimposed on to recent cladograms for the family.The results strongly indicate that reduction in chromosome numberoccurs with evolutionary advancement. Thus Epacridaceae, incommon with ‘Ericaceaesens. strict .’ and ‘Vacciniaceaesens.strict. ’, has evolved from a primitive karyotype of atleastx =12 and probablyx =13. This conclusion dispels earlierpaleopolyploid models based on a primitivex =6 in the family.Other aspects of cytoevolution, such as chromosome number asa generic character especially in cytologically advanced generaof the Styphelieae, are discussed. Cytoevolution; cladistic models; primitive character states for chromosome number; dysploid falls; cytotaxonomy; Epacridaceae; Richeoideae; Epacridoideae; Epacrideae; Styphelieae; Ericaceae     

Combining a regional climate model with a phytoplankton community model to predict future changes in phytoplankton in lakes

1. Linking a regional climate model (RCM) configured for contemporary atmospheric greenhouse gas concentrations, with a phytoplankton community model (PROTECH) produced realistic simulations of 20 years of recent phytoplankton data from Bassenthwaite Lake, in the North‐West of England. 2. Meteorological drivers were derived from the RCM to represent a future climate scenario involving a 1% per annum compound increase in atmospheric CO₂ concentrations until 2100. Using these drivers, PROTECH was run for another 20 year period representing the last two decades of the 21st century. 3. Comparison of these present and future simulations revealed likely impacts on the current seasonal phytoplankton development. Under future climate conditions, the simulated spring bloom showed an increase in cyanobacteria dominance caused by greater success of Planktothrix. Also, the summer cyanobacteria bloom declined earlier because of nutrient limitation caused by the increased spring growth. Overall productivity in the lake did not change. 4. Analysis showed that these predicted changes were driven by changes in water temperature, which were in turn triggered by the higher air temperatures predicted by the RCM.