Reciprocal Allogrooming in Dam-reared and Hand-reared Impala Fawns

Among adult females and males of African antelope impala are unique in their performance of reciprocal allogrooming. The occurrence of this behaviour in neonatal impala fawns was explored in a free-ranging impala herd at the San Diego Wild Animal Park where 5 dam-reared fawns were observed from birth through 10 weeks of age. One-way maternal grooming and reciprocal allogrooming with the dam and non dam partners emerged as distinct behavioural systems. Maternal grooming, directed mostly to the anogenital area, was typical of that seen in other ungulates, and sharply declined over the first two weeks. Reciprocal allogrooming, characterized by alternate exchanges of grooming bouts with a partner in the same manner as in adults, was seen as early as 3–8 d after birth. All fawns were grooming with unrelated adult females by the end of the second week. By week 2 virtually every measure of reciprocal allogrooming by fawns (grooming delivered per hour, reciprocity, and percent of encounters initiated) was as high as for adults. The appearance of this reciprocal allogrooming pattern, especially at such an early age, appears to be unique among ungulates, and possibly mammals in general. Three hand-reared impala fawns, deprived of the opportunity to interact with older herdmates, but having access to impala fawns and heterospecific fawns, were observed from 1–3 mo of age. The hand-reared impala showed no alteration in the occurrence of reciprocal allogrooming behaviour compared with the dam-reared control fawns, indicating that allogrooming experience with older animals was not required for the appearance of reciprocal allogrooming at an early age. Interestingly, hand-reared fawns persisted in grooming heterospecific fawns despite the fact that heterospecifics rarely reciprocated grooming. We postulate that the strong predisposition for impala young to groom others may be related to the threat of tick infestation in the impala's ecotone habitat.     

DNase I hypersensitivity and expression of the Shrunken-1 gene of maize

The local chromatin structure of the Shrunken-1 (Sh) gene of maize was probed by analyzing DNase I hypersensitivity. Sh encodes the gene for sucrose synthetase, a major starch biosynthetic enzyme, which is maximally expressed in the endosperm during seed maturation. In addition to general DNase I sensitivity, specific DNase I hypersensitive sites were identified in endosperm chromatin that mapped near the 5 end of the Sh gene. The pattern of hypersensitive sites and their relative sensitivity were altered in other non-dormant tissues that produce little or no enzyme. However, some changes in chromatin structure appear to be independent of Sh gene expression and may reflect general alterations associated with plant development. The chromatin structure of several sh mutations, induced by Ds controlling element insertions, was also analyzed. Although the insertions perturbed expression of the gene, there were no notable effects on local chromatin structure.     

Energization and activation of inorganic carbon uptake by light in cyanobacteria

The requirement of the inorganic carbon (C_i) transport system for light in cyanobacteria was investigated in Anabaena variabilis by the filtering centrifugation technique and in a mutant (E₁) isolated from Anacystis nidulans using a gas exchange system. C_i transport capability increased with time of preillumination and decreased following darkening. Full activity could not be obtained by operating either photosystem II (PSII) or photosystem I alone. 3(3,4 Dichlorophenyl)-1,1 dimethylurea strongly inhibited C_i uptake. Very low activity of PSII was sufficient to activate C_i uptake. However, in the presence of dithiothreitol PSII activity was not required. We conclude that light may be required to activate as well as to energize C_i uptake in cyanobacteria.     

Rhythmic activity of the endbrain in the carp evoked by adequate visual stimulation

In acute experiments on immobilized carps, under dark adaptation conditions, studies have been made on the electrical activity of the telencephalon and midbrain tectum. It was found that in the latter photostimulation evokes local rhythmic activity which includes fast (30-50 Hz) phasic (200-300 ms) and slow (8-14 Hz) tonic (up to 3-4 s) components. High rhythm of this activity may be observed only in "healthy" preparations, coinciding with on-rhythm in the midbrain tectum. Low rhythm does not depend on the presence of rhythmic activity in the tectum. Various aspects of the development of the thalamo-telencephalic system in vertebrates are discussed.     

Reference ranges of retinol, tocopherols, lycopene and alpha- and beta-carotene in plasma by simultaneous high-performance liquid chromatographic analysis

Using a high-performance liquid chromatographic procedure, age- and gender-based reference ranges for plasma retinol, alpha- and gamma-tocopherol, lycopene, and alpha- and beta-carotene have been established. In addition to confirming higher retinol levels in men than in women (p less than 0.001), this study demonstrates significantly higher plasma levels of both carotenes in women than in men (p less than 0.001). The plasma levels of retinol and beta-carotene showed a positive relationship with age after adjusting for plasma lipids (p less than 0.001 and p less than 0.02, respectively). In contrast to beta-carotene, there was no gender difference for plasma lycopene and a strong (p less than 0.001) inverse relationship of lycopene with age. These results suggest that differences may exist between beta-carotene and lycopene in their intestinal absorption, plasma transport, or tissue metabolism.     

Genetic counseling and prenatal diagnosis in Duchenne myopathy: yesterday, today and tomorrow

The coming of molecular biology has greatly modified the concept of genetic counselling and prenatal diagnosis of Duchenne muscular dystrophy. The most important stages of the genetic counselling are reported: estimate of the risk and carrier detection. This heterozygote detection is now possible in a few cases owing to polymorphic DNA markers recently identified that are genetically linked to the DMD gene locus and detected with probes. An analysis of foetal DNA is also possible and allows us to consider prenatal diagnosis of this affection. This study is yet limited by two impediments: on one hand low rate of informative families, on the other hand use of markers that are not very closely linked to DMD involving recombinations and risks of errors. The solution of these problems is in the use of linked DNA markers with the best polymorphism flanking the Duchenne muscular dystrophy locus. Finally the authors report the necessity of strict collaboration systems between clinical experts, geneticists, biologists and informaticians.     

Structural and dynamic properties of a fluorouracil-adenine base pair in DNA studied by proton NMR

An oligodeoxynucleotide duplex containing the chemotherapeutic agent 5-fluorouracil (FU) has been constructed by solid phase phosphotriester synthesis and has been studied in solution by proton NMR. In this study, we provide the first structural characterization of a DNA complex containing a FU.A base pair. It has been determined that the 7-mer duplex containing a central FU.A base pair adopts a normal right-handed configuration and the A residue in the FU.A pair is oriented in the normal anticonfiguration giving a Watson-Crick base pair. The significant difference between T.A and FU.A base pairs is dynamic, not structural: the FU.A base pair opens faster than normal base pairs in the oligonucleotide studied. We provide evidence that the FU.A base pair has a significantly enhanced opening rate resulting form decreased stacking of the 5-fluorouracil residue and not from the enhanced acidity of the 5'-fluorouracil imino proton.