U1 SnRNP association with HnRNP involves an initial non-specific splice-site independent interaction of U1 SnRNP protein with HnRNA.

Precursor mRNA is complexed with proteins in the cell nucleus to form heterogeneous nuclear ribonucleoprotein (hnRNP), and these hnRNPs are found associated in vivo with small nuclear RNPs (snRNPs) for the processing of pre-mRNA. In order to better characterize the ATP-independent initial association of U1 snRNP with hnRNP, an important early event in assembly of the spliceosome complex, we have determined some of the components essential to an in vitro reassociation of U1 snRNP with hnRNP. U1 snRNP reassociated in vitro with 40S hnRNP particles from HeLa cells and, similar to the in vivo hnRNP/U1 snRNP association, the in vitro interaction was sensitive to high salt concentrations. U1 snRNP also associated with in vitro reconstituted hnRNP in which bacteriophage MS2 RNA, which lacks introns, was used as the RNA component. Purified snRNA alone would not associate with the MS2 RNA-reconstituted hnRNP, however, intact U1 snRNP did interact with protein-free MS2 RNA. This indicates that the U1 snRNP proteins are required for the hnRNP/U1 snRNP association, but hnRNP proteins are not. Thus, the initial, ATP-independent association of U1 snRNP with hnRNP seems to be mediated by U1 snRNP protein(s) associating with hnRNA without requiring a splice-site sequence. This complex may then be further stabilized by intron-specific interactions and hnRNP proteins, as well as by other snRNPs.

Moving sound sources: techniques and applications.

A stimulating device for the application of moving acoustic signals of varying form and velocity is described. The apparatus functions on the principle of intensity stereophony and permits continuous smooth sound movements in a vast range of different forms and frequencies. Furthermore, simultaneous application of vestibular and optokinetic stimuli is possible. Cortically evoked potentials, voluntary and involuntary eye movements, and influences upon body sway from moving acoustic signals are offered as examples for applicability.

Voluntary ocular tracking movements in response to a sinusoidally moving intermittently active sound source.

Voluntary eye movements in response to a sinusoidally moving, intermittently active sound source were investigated in 40 young healthy human subjects. Visual afferent input was prevented during the experiments. With increasing burst repetition rates of the sound source, different forms of eye movements were observed: a) so-called single and repetitive adversive movements consisting of saccades which occur with certain latencies in response to single bursts; b) so-called saccadic eye tracking movements which are characterized by numerous small saccades occurring in accordance with the target (sound source) movement but lacking a time correlation between the saccades and single bursts. It was found that saccadic eye tracking movements were performed instead of adversive movements when at least 4 to 10 bursts per movement period of the sound source was transmitted (with movement frequencies of the sound source from 0.1 to 0.5 Hz). Slight intersaccadic drifts, which could be regularly observed in all types of eye movements were interpreted as instability of fixation in darkness.

Form and accuracy of voluntary ocular tracking movements in response to sinusoidally moving acoustic targets.

Form and accuracy of voluntary ocular tracking in response to a horizontal sinusoidally moving auditory stimulus were examined in complete darkness. Forty young, healthy subjects participated in the study. Ocular movements under the applied experimental conditions consisted of a succession of saccades whose direction corresponded to the motion of sound. Though slight intersaccadic drifts were observed, pure smooth pursuit movements could not be recorded. A comparison of the amplitude of sound motion and the corresponding ocular motion showed the latter to be rather inaccurate. Independent of the actual amplitude of the sound motion (+/- 15 degrees up to +/- 90 degrees) the amplitude of the ocular movements, in most cases, remained constant within a range of approximately +/- 35 degrees to +/- 45 degrees. The accuracy in respect to phase relationship between target movement and ocular response was quite good. In response to sinusoidal motion of the sound, the ocular movements usually occurred simultaneously up to 0.5 Hz.

Acoustic-induced eye movements.

This article reports the influence of moving acoustic signals on eye movements (oculomotor functions) using 350 healthy test subjects. An acoustic test setting developed especially for this purpose has made possible the application of moving acoustic signals of varying frequency and form (square stimuli, sinusoidal stimuli, circular movements), as well as the examination of visual-acoustic and vestibular-acoustic interactions. It must be stressed that according to these investigations, both voluntary and involuntary eye movements can be demonstrated in response to moving acoustic signals. Involuntary eye movements, however, under th given experimental conditions, only are observed in about 20% of all test subjects and their frequency of occurrence is highest in young female subjects. They are most pronounced in darkness and when there is no fixation, and they can be coupled to varying degrees with the given acoustic signal. Voluntary and involuntary eye movements do not differ very much from one another. They consist mainly of a series of saccades that form staircase jerks. In both cases, no typical smooth movements or nystagmoid movement forms occur--which are predominant in tracking eye movements of visual stimuli. Occasionally, slight drifting movements can be demonstrated in the intersaccadic intervals. At a larger movement amplitude and increased movement frequency of the sound signal, pure opposite jerks finally appear, which follow up to a movement frequency of 1 Hz. The eye movements are influenced only slightly by a change in the amplitude of the sound movement (+/- 15 degrees to +/- 90 degrees). However, a close phase relationship between eye and sound movement exists. If instead of continuous acoustic signals (music), single burst signals are given at an increasing repetition rate, this results (at low repetition rates of bursts) in orienting reactions upon the individual signals, while at high signal repetition rates (above 0.5 Hz), continuous eye movements in the form of staircase jerks result. In investigating acoustically induced tracking eye movements, many new questions have arisen that previously have been open only to psychophysical studies.

[Klüver-Bucy syndrome and primitive motor reflexes after heavy brain trauma (author's transl)]. / Klüver-Bucy-Syndrom und Greifreflexe (oral, cheiral, podal) nach schwerer Hirnkontusion.

A 16-year-old physically and mentally retarded male developed a complete Klüver-Bucy syndrome similar to that demonstrated in animal experiments and characterized by so-called psychic blindness, oral tendencies, hypermetamorphosis, emotional disturbance, and hypersexuality after severe brain trauma with loss of consciousness and a transitory hemiplegia. In addition, transitory oral and grasp reflexes were observed. Despite the severity of the clinical symptoms, the patient was able to realize and report on his subjective experience of the reflex and on the instinct-motivated behavior associated with the Klüver-Bucy syndrome. In the case described, two basic behavior patterns could be differentiated, each influencing drive and the abnormally increased sexuality. The first phase of the illness was dominated by relatively constant automatic reactions. These had the character of pre-determined instinctive behavior and were more or less emotionally neutral. In the second phase of the illness, the instinctive behavior became less evident and the patient was able to respond more normally to his sensory-motor impulses. Also, emotional experience such as frustration, pleasure, and displeasure regained their meaning for the patient.

[The influence of alcohol on central nervous compensating mechanisms following labyrinthic lesions (author's transl)]. / Der Einfluss von Alkohol auf die zentralnervösen Ausgleichsvorgänge nach Labyrinthausschaltung.

The influence of alcohol on mechanisms compensating for labyrinthine lesions was studied in 180 guinea-pigs. The animals were subjected to either unilateral or to successive bilateral labyrinthectomy which was induced by an injection of chloroform into the middle ear. No significant influences of alcohol on vestibular compensation were found up to alcohol levels of 1g/kg. Dosages higher than 2 g/kg exerted inhibitory effects on compensation after unilateral labyrinthectomy. Compensation after successive bilateral labyrinthine lesions could not clearly be influenced. In animals which had achieved natural compensation after labyrinthectomy alcohol dosages of 0,5--1 g/kg re-elicited some of the formerly present symptoms. The data presented are interpreted with regard to their significance for the action of alcohol patients with cerebral dysfunction.

Nucleotide modification in vitro of the precursor of transfer RNA of Escherichia coli.

Certain nucleotides in precursor RNA of tRNA(Tyr) of Escherichia coli were modified in vitro with a preparation of partially purified E. coli enzyme containing ribothymidine- and pseudouridine-forming activity. The only nucleotides modified in vitro are the same as those found modified in mature tRNA. The best substrate for these modifying enzymes is the RNase P cleavage product of the precursor RNA, which contains the mature tRNA sequence. Of the two pseudouridines found in mature tRNA, one (in the TPsiC sequence) can be formed in intact precursor RNA. The other (in the anticodon stem) can only be formed in the cleaved precursor RNA. The presence of modified nucleotides in the precursor RNA does not enhance its rate of cleavage by RNase P.