Fine mapping of the Autosomal Dominant Split Hand/Split Foot Locus on Chromosome 7, Band q21.3-q22.1

Split hand/split foot (SHFD) is a human developmental defect characterized by missing digits, fusion of remaining digits, and a deep median cleft in the hands and feet. Cytogenetic studies of deletions and translocations associated with this disorder have indicated that an autosomal dominant split hand/split foot locus (gene SHFD1) maps to 7q21-q22. To characterize the SHFD1 locus, somatic cell hybrid lines were constructed from cytogenetically abnormal individuals with SHFD. Molecular analysis resulted in the localization of 93 DNA markers to one of 10 intervals surrounding the SHFD1 locus. The translocation breakpoints in four SHFD patients were encompassed by the smallest region of overlap among the SHFD-associated deletions. The order of DNA markers in the SHFD1 critical region has been defined as PON–D7S812–SHFD1–D7S811–ASNS. One DNA marker, D7S811, detected altered restriction enzyme fragments in three patients with translocations when examined by pulsed-field gel electro-phoresis (PFGE). These data map SHFD1, a gene that is crucial for human limb differentiation, to a small interval in the q21.3-q22.1 region of human chromosome 7.     

Subject: Navigation and orientation

Research Notes on Avian Biology 1994: Selected Contributions from the 21st International Ornithological CongressMorphology and Physiology: Orientation

Subject: Navigation and orientation     

Lantana,or red sage (Lantana camara L., [Verbenaceae]), notorious weed and popular garden flower; some cases of poisoning in Florida

Lantana, or red sage (lantana camara, Verbenaceae) is an aromatic shrub with rough, opposite or whorled leaves and four-angled, prickly or smooth stems, showy heads of small flowers (usually pink-and-yellow changing to red-and-orange) and dark-blue or blackish fruits. Native from tropical America north to lower Texas and southern Georgia, the bird-distributed plant has become naturalized in the Caribbean area, the Pacific islands, Australia, New Zealand, South Africa and southern Asia. Hundreds of cultivars are grown as ornamentals in temperate climates. In warm regions, L. camara is a pest in farms, pastures and forests, providing breeding places for diseases, detrimental animals and insects, including the tsetse fly. Of 29 named races in Australia, 19 are toxic or gravely pestiferous. Active principles are the triterpenes lantadene A and B. Ingestion of 340-453 g of leaves causes liver and kidney damage, photosensitization, intestinal hemorrhage, paralysis of the gall bladder, and death in 1-4 days in horses, cattle and sheep (not goats). Ripe fruits are edible, but green, unripe fruits have caused illness and one known fatality in children in Florida. Leaves and roots are popular folk remedies. Stems are used as toothbrushes, and the leaves for polishing wood. Prickly races are grown as protective hedges around forest dwellings.     

Regulation of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activity in Response to Reduced Light Intensity in C4 Plants

The light-dependent regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity was studied in 16 species of C4 plants representing all three biochemical subtypes and a variety of taxonomic groups. Rubisco regulation was assessed by measuring (a) the ratio of initial to total Rubisco activity, which reflects primarily the carbamylation state of the enzyme, and (b) total Rubisco activity per mol of Rubisco catalytic sites, which declines when 2-carboxyarabinitol 1-phosphate (CA1P) binds to carbamylated Rubisco. In all species examined, the activity ratio of Rubisco declined with a reduction in light intensity, although substantial variation was apparent between species in the degree of Rubisco deactivation. No relationship existed between the degree of Rubisco deactivation and C4 subtype. Dicots generally deactivated Rubisco to a greater degree than monocots. The total activity of Rubisco per catalytic site was generally independent of light intensity, indicating that CA1P and other inhibitors are not major contributors to the light-dependent regulation of Rubisco activity in C4 plants. The light response of the activity ratio of Rubisco was measured in detail in Amaranthus retroflexus, Brachiaria texana, and Zea mays. In A. retroflexus and B. texana, the activity ratio declined dramatically below a light intensity of 400 to 500 [mu]mol of photons m-2 s-1. In Z. mays, the activity ratio of Rubisco was relatively insensitive to light intensity compared with the other species. In A. retroflexus, the pool size of ribulose bisphosphate (RuBP) declined with reduced light intensity except between 50 and 500 [mu]mol m-2 s-1, when the activity ratio of Rubisco was light dependent. In Z. mays, by contrast, the pool size of RuBP was light dependent only below 350 [mu]mol m-2 s-1. These results indicate that, in response to changes in light intensity, most C4 species regulate Rubisco by reversible carbamylation of catalytic sites, as commonly observed in C3 plants. In a few species, notably Z. mays, Rubisco is not extensively regulated in response to changes in light intensity, possibly because the activity of the CO2 pump may become limiting for photosynthesis at subsaturating light intensity.     

HLA class II nucleotide sequences, 1992

The HLA class II sequences included in this compilation are taken from publications listed in the papers: Nomenclature for factors of the HLA system, 1989, Nomenclature for factors of the HLA system, 1990, and Nomenclature for factors of the HLA system, 1991 (WHO Nomenclature Committee 1990, 1991, 1992). Where discrepancies have arisen between reported sequences, the original authors have been contacted where possible, and necessary amendments to published sequences have been incorporated into this alignment. Future sequencing may identify errors in this list, and we would welcome any evidence that helps to maintain the accuracy of this compilation. In the sequence alignments, identity between residues is indicated by a hyphen (-), an unavailable sequence is indicated by an asterisk (*), and gaps in the sequence are inserted to maintain the alignment between different alleles showing variation in amino acid number. Correspondence to: S. G. E. Marsh.     

Fusion protein mediated prodrug activation (FMPA) in vivo

A two component system, consisting of a fusion protein and an appropriate prodrug, suited to perform selective tumor therapy in vivo, is presented. The fusion protein, owing to its humanized carcinoembryonic antigen (CEA)-specific variable region, specifically binds to CEA-expressing tumors and has an enzymatic activity comparable to human β-glucuronidase. The prodrug is a nontoxic glucuronide-spacer-derivative of doxorubicin decomposing to doxorubicin by enzymatic deglucuronidation. In vivo studies in nude mice bearing human CEA-expressing tumor xenografts revealed that 7 d after injection of 20 mg/kg fusion protein, a high specificity ratio (>100:1) was obtained between tumor and plasma. Injection of 250 mg/kg of prodrug at d 7 resulted in tumor therapeutic effects superior to conventional chemotherapy without any detectable toxicity. These superior therapeutic effects that were observed using established human tumor xenografts can be explained by the approx 10-fold higher drug concentrations found in tumors of mice treated with fusion protein and prodrug than in those treated with the maximal tolerable dose of drug alone.     

Polyamine regulation of Na+/glucose symporter expression in LLC-PK1 cells

Addition of polyamines or their analogs to newly confluent LLC-PK₁ cells resulted in down-regulation of Na⁺-glucose transport (symport) activity. Polyamines prevented the induction of this symporter by the differentiation inducer hexamethylene bisacetamide (HMBA) but did not influence induction by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Partial depletion of endogenous polyamines after addition of α -difluoromethylornithine (DFMO) resulted in a 4 to 5-fold increase in symporter expression. Symporter induction by either HMBA or DFMO was inhibited by the protein kinase inhibitor H-7 but H-7 did not affect symporter induction by IBMX. Changes in symporter activity were accompanied by changes in levels of the 75 kD symporter subunit detected by Western blot. Cultures exposed to HMBA exhibited reduced levels of ornithine decarboxylase activity. Our results suggest that induction of symporter expression by HMBA may be mediated in part by its effects on polymine metabolism, and point to parallel roles of polyamines and cyclic AMP in regulating the expression of this physiologically important renal transport system. © 1993 Wiley-Liss, Inc.     

Pan-Arctic soil moisture control on tundra carbon sequestration and plant productivity

Long-term atmospheric CO₂ concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength. In this study, we used a record of nearly 100 site-years of eddy covariance data from 11 continuous permafrost tundra sites distributed across the circumpolar Arctic to test the temperature (expressed as growing degree days, GDD) responses of gross primary production (GPP), net ecosystem exchange (NEE), and ecosystem respiration (ER) at different periods of the summer (early, peak, and late summer) including dominant tundra vegetation classes (graminoids and mosses, and shrubs). We further tested GPP, NEE, and ER relationships with soil moisture and vapor pressure deficit to identify potential moisture limitations on plant productivity and net carbon exchange. Our results show a decrease in GPP with rising GDD during the peak summer (July) for both vegetation classes, and a significant relationship between the peak summer GPP and soil moisture after statistically controlling for GDD in a partial correlation analysis. These results suggest that tundra ecosystems might not benefit from increased temperature as much as suggested by several terrestrial biosphere models, if decreased soil moisture limits the peak summer plant productivity, reducing the ability of these ecosystems to sequester carbon during the summer.     

The protective value of the colour and shape of the mountain katydid's antipredator defence

Deimatic behaviour is performed by prey when attacked by predators as part of an antipredator strategy. The behaviour is part of a sequence that consists of several defences, for example they can be preceded by camouflage and followed by a hidden putatively aposematic signal that is only revealed when the deimatic behaviour is performed. When displaying their hidden signal, mountain katydids (Acripeza reticulata) hold their wings vertically, exposing striking red and black stripes with blue spots and oozing an alkaloid-rich chemical defence derived from its Senecio diet. Understanding differences and interactions between deimatism and aposematism has proven problematic, so in this study we isolated the putative aposematic signal of the mountain katydid's antipredator strategy to measure its survival value in the absence of their deimatic behaviour. We manipulated two aspects of the mountain katydid's signal, colour pattern and whole body shape during display. We deployed five kinds of clay models, one negative control and four katydid-like treatments, in 15 grids across part of the mountain katydid's distribution to test the hypothesis that their hidden signal is aposematic. If this hypothesis holds true, we expected that the models, which most closely resembled real katydids would be attacked the least. Instead, we found that models that most closely resembled real katydids were the most likely to be attacked. We suggest several ideas to explain these results, including that the deimatic phase of the katydid's display, the change from a camouflaged state to exposing its hidden signal, may have important protective value.