Isolation and subregional mapping of a human cDNA clone detecting a common RELP on chromosome 12

Summary Peripheral blood lymphocytes from three patients with Down syndrome (DS; trisomy 21; aged 5–6 years) and three age-matched control children were studied for the induction of chromosomal aberrations and sister chromatid exchanges (SCEs).Cells in G₀ were exposed to bleomycin (20–100 g/ml) for 3 h, and then cultured in medium containing 5-bromodeoxyuridine and phytohemagglutinin for 66 h. By the sister chromatid differential staining method, chromosome analyses were performed on metaphase cells that had divided one, two, or three or more times after treatment. The results indicate that DS cells exposed to bleomycin are hypersensitive to the production of dicentric and ring chromosomes compared to normal cells. Bleomycin also led to a dose-related increase in the frequency of SCEs, but no difference was found between the SCE frequencies in DS or normal lymphocytes exposed to bleomycin.     

Spore Load of Ascosphaera Species on Emerging Adults of the Alfalfa Leafcutting Bee, Megachile rotundata

The spore load of Ascosphaera species spores on larval chalkbrood cadavers and newly emergent adults of the alfalfa leafcutting bee, Megachile rotundata, was determined. The spore content of chalkbrood cadavers ranged from 3 × 10⁶ to 5 × 10⁸. Adults emerging through zero to nine cadavers carried spores on all body parts examined by scanning electron microscopy. Estimates of the total number of spores obtained from a series of adult washes ranged from 9 × 10⁴ to 8 × 10⁷. Some adult males which emerged through no cadavers carried 10⁴ to 10⁵ spores, indicating that nesting materials might also have been contaminated. However, the control of chalkbrood in commercial bee populations may not be accomplished simply by providing clean nesting materials as adults may still emerge through diseased larvae.     

Genetic studies of the lac repressor. IX. Generation of altered proteins by the suppression of nonsence mutations.

We have generated more than 300 altered lac repressor proteins carrying known amino acid replacements, by employing nonsense mutations at 90 positions in the lacI gene together with eight different nonsense suppressors. This allows the substitution of lysine, serine, tyrosine, leucine and glutamine at virtually all of the respective positions in the repressor, and tryptophan at ten positions in the repressor. Since most of the nonsense sites have been correlated with specific codons in the lacI messenger RNA, in almost all cases the position of the substituted residue is known. This process results in the creation of a large number of mutant phenotypes. We have analyzed the effects of each substitution in vivo, and in several cases studied partially purified repressors in vitro. The properties of the altered proteins have been compared with the position and nature of each exchanged residue. We discuss the implications of these findings with regard to repressor structure in particular, and to protein structure in general. Further applications of the suppression method are also considered.     

Development of a system useful for studying the formation of unstable alleles of IS2

Summary IS2-induced deletions of the gal control region were isolated in a plasmid carrying gal OP-308 :: IS2-7. This contains a 54 basepair long, unstable mini insertion within IS2, thus allowing constitutive expression of the gal structural genes. Deletion PPI is 11.9 kilobasepairs (kb) long and is Gal⁺ because it has retained the mini insertion. In PP4 7.2 kb DNA material including markers gal OP, chlD and pgl are deleted. PP4 has lost the mini insertion and is therefore Gal negative. DNA sequencing of the newly formed junction in PP4 reveals that the deletion terminates precisely at nucleotide 1 of IS2 and that no DNA sequence homology is involved in this IS2-mediated deletion formation. PPI segregates Gal^- clones due to the loss of the mini insertion. One such segregant PPIS and PP4 both give only constitutive Gal⁺ revertants, which consist of the previously known mini insertions and also a new class of supermini inserts within IS2 of about 10 to 20 basepairs long. Therefore, PPIS and PP4 can be used to study various parameters involved in the formation of mini insertions.     

Die Belichtungsreaktionen sessiler Crustaceen(Balanus balanus) als Alternative zu den Schutzreaktionen bodenbewohnender mariner Wirbelloser

Shadow responses, including reactions to both increase (on) and decrease (off) in light intensity have been hitherto described in the adults of various bottom-dwelling marine invertebrates. These reactions as expressed by decrease in activity are assumed to be protective (withdrawal responses, kinetic rigidity after v. Buddenbrock, 1952). By contrast, the free-swimming larvae of these species normally show increase in activity to both increase and decrease in light intensity as expressed by negative or positive photoresponses. In the sessile barnacleBalanus balanus L. reactions to increase in light intensity are demonstrated which, contrary to the withdrawal responses or kinetic rigidity, result in an increase of cirral activity. The shadow responses of the barnacles (off responses) are described as withdrawal responses. The light responses are expressed by two different modes of behaviour: (a) If an active barnacle is stimulated by increase in light intensity, the frequency of cirral activity increases; (b) if an inactive barnacle is stimulated by increase in light intensity, the cirral activity arises a short time later. The light responses observed are interpreted as a metamorphosis of larval swimming activity.

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Gefördert von der Deutschen Forschungsgemeinschaft     

Evolutionary conservation of a microbody targeting signal that targets proteins to peroxisomes, glyoxysomes, and glycosomes.

Peroxisomes, glyoxysomes, glycosomes, and hydrogenosomes have each been classified as microbodies, i.e., subcellular organelles with an electron-dense matrix that is bound by a single membrane. We investigated whether these organelles might share a common evolutionary origin by asking if targeting signals used for translocation of proteins into these microbodies are related. A peroxisomal targeting signal (PTS) consisting of the COOH-terminal tripeptide serine-lysine-leucine-COOH has been identified in a number of peroxisomal proteins (Gould, S.J., G.-A. Keller, N. Hosken, J. Wilkinson, and S. Subramani. 1989. J. Cell Biol. 108:1657-1664). Antibodies raised to a peptide ending in this sequence (SKL-COOH) recognize a number of peroxisomal proteins. Immunocryoelectron microscopy experiments using this anti-SKL antibody revealed the presence of proteins containing the PTS within glyoxysomes of cells from Pichia pastoris, germinating castor bean seeds, and Neurospora crassa, as well as within the glycosomes of Trypanosoma brucei. Western blot analysis of purified organelle fractions revealed the presence of many proteins containing this PTS in both glyoxysomes and glycosomes. These results indicate that at least one of the signals, and therefore the mechanism, for protein translocation into peroxisomes, glyoxysomes, and glycosomes has been conserved, lending support to a common evolutionary origin for these microbodies. Hydrogenosomes, the fourth type of microbody, did not contain proteins that cross-reacted with the anti-PTS antibody, suggesting that this organelle is unrelated to microbodies.     

G-proteins in etiolated Avena seedlings. Possible phytochrome regulation

The molecular mechanism of light signal transduction in plants mediated by the photosensor phytochrome is not well understood. The possibility that phytochrome initiates the signal transduction chain by modulating a G-protein-like receptor is examined in the present work. Etiolated Avena seedlings contain G-proteins as examined in terms of the binding of GTP as well as by cross-reaction with mammalian G-protein antibodies. The binding of GTP was regulated in vivo by red/far-red light. The possible involvement of G-proteins in the phytochrome-mediated signal transduction in etiolated Avena seedlings has been implicated from the study of the light regulated expression of the Cab and phy genes.     

High-affinity kainate and domoate receptors in rat brain.

Mammalian brain expresses receptors which bind the potent neurotoxins, kainate and domoate, with high affinity, and which form a subclass of ionotropic glutamate receptors. A new member of these receptors, expressed in both adult and embryonic CNS is compared in its ligand binding properties to its closely sequence-related homologs.     

Ammonia volatilization after injection of anhydrous ammonia into arable soils of different moisture levels

Laboratory experiments have shown appreciable losses of ammonia after injection of anhydrous ammonia into dry and wet soils. In this study losses of ammonia injected into a moist (tension 10 kPa), dry (tension 160 kPa) and a wet (tension 1.6 kPa) sandy loam were measured under field conditions using wind tunnels. Losses were insignificant from a moist soil. However losses from a dry and a wet soil were 20% and 50% of injected ammonia, respectively. From the dry soil, losses of gaseous ammonia took place within the first hours after injection, which indicates a rapid transport through cracks and voids. From the wet soil, 20% of the injected ammonia was lost more gradually between 6 h and 6 d. This indicates that upward movement of water due to evaporation may be the cause of these ammonia losses which proceeded for longer periods.     

Evidence for sexually selected infanticide in captiveCercopithecus mitis,Cercocebus torquatus,andMandrillus leucophaeus

Adult resident males of one-male-multi-female primate groups housed at the Hannover Zoo exhibited aggression, when confronted with nonadult individuals, which were fathered by other males: (1) a new adult resident male in a group of blue monkeys killed a 5.8-month-old female infant: (2) a new adult resident male in a group of white collared mangabeys injured a 24.0-month-old female and an 18.9-month-old male severely; they would have died without veterinary care; and (3) the resident male of a group of drills threatened an 1.8-month-old foreign female infant seriously; efforts to introduce the infant were discontinued. Pathological explanations are unlikely because the adult males showed no aggression towards own nonadult offspring under the same captive conditions. By and large, the events support the theory that infanticide is the result of sexual selection among males.