Deductive biology—Some cautious steps

For certain environments, the Darwinian model allows unique prediction of a function that any surviving system adapted to such an environment has to perform. This is the case for those environments that determine a “survival functional” of position in space-time of known shape. Purely temporal survival functionals can be distinguished from spatial and mixed ones. In each case, there exists an optimum path in combined physical and (reduced) metabolic space. Dependent on the admissible error, approximate solutions of different complexity are sufficient. All solutions possess an afferent, a central, and an efferent part. Within this general frame, specific, “probably simplest”, solutions are proposed for adaptive chemotaxis, insect locomotion, lower vertebrates locomotion, higher vertebrates locomotion, chronobiological systems, and immune systems, respectively—or rather, for the underlying functionals. Presented at the Society for Mathematical Biology Meeting, University of Pennsylvania, Philadelphia, August 19–21, 1976.     

Repeated characterization, analysis of variance limitation and discrimination analysis classification of EEG-activity patterns in human sleep]

1. To describe quantitatively and to deliminate nine EEG sleep patterns, mean values and standard deviations of abundances of the frequencies 0.8 ... 1.8 c/sec, 2...3.5 c/sec, 4...13c/sec, 14 to 17 c/sec, 18 to 22 c/sec, and 23 to 40 c/sec as well as of the average amplitudes in selected frequency ranges were calaculated and the distributions represented. 2. All nine EEG activity patterns could be separated by means of univariate and multivariate analyses of variance on the basis of all 28 as well as the 17 indispensable variables. 3. In the course of a stepwise reduction of variables within the framework of a linear discriminant analysis an optimal set of 17 variables was determined for the separation of the patterns, comprising: the percent quantity of the frequencies 0.8 ... 3.5 c/sec, 7 ... 9 c/sec and 18 to 40 c/sec as well as the average amplitudes in the frequency ranges 0.8 to 3.5 c/sec and 7.5 to 40 c/sec. 4. By linear regression analyses it could be shown that the sleep scording system used, can be reflected on an interval scale with the aid of discriminant functions; this can be achieved on the basis of the optimal set of variables as well as of the five most indispensable variables. 5. Finally the degree of the objectivity of the scoring procedures was demonstrated. Advantages and disadvantages of sleep scoring systems were discussed and possibilities of the utilization of results suggested, also in respect to the further development of the automatic recognition of EEG activity patterns.     

Strukturanalyse der methyl-2,3,6-tridesoxy-2-C-[2-hydroxy-1,1-(Äthylendithio)Äthyl]-α-l-threo-hexopyranosid-4-ulo-22,4-pyranose

Methyl 2,3,6-trideoxy-2-C-[2-hydroxy-1,1-(ethylenedithio)ethyl]-α-l-threo-hexopyranosid-4-ulo-2²,4-pyranose (1) crystallizes in a rhombic space group P2₁2₁2₁ with four molecules in the elementary unit. The structure was refined to an R-value of 0.057. The aldopyranose ring adopts a ¹C₄ conformation with an axial side-chain forming a hemiacetal ring to the keto group at C-4. Both six-membered rings connected in the 2,7-dioxabicyclo[3.3.1]nonane system differ only slightly from the ¹C₄ chair conformation. The spirocyclic dithiolane ring adopts a nearly ideal envelope form with a deviation of C-21 from the plane S-1-C-7-S-2-C-22. The dihedral angle O-5-C-1 O-1-C-11 of 59.1° is an agreement with the exo-anomeric effect.     

A subordinal classification of frogs (Amphibia: Anura)

Two new anuran suborders, based on two states of the trigeminofacial ganglion character complex are proposed. A subsidiary character is the presence or absence of free ribs in extant taxa. These new suborders are more clades (sister groups) than sequential levels of organization. Discoglossoidei, retaining separate trigeminal and facial ganglia and free ribs, encompasses only Leiopelmatidae and Discoglossidae, although by definition it would include the common ancestor of both lineages. Ranoidei have the trigeminal and facial ganglia fused and extant taxa lack free ribs. This group includes all other frogs.
Only the superfamiliesPelobatoidea and Pipoidea are reallocated by the new arrangement. The former are now regarded as representing the ranoidean stem group. Both laival and adult morphology show that pipoids are highly derived rather than primitive frogs, and their trigeminofacial systems show that they are ranoideans rather than discoglossoideans. They presumably are ultimately derived from pelobatoids, but the known taxa are too specialized for direct derivation and there must have been an intermediate group with pipoid tadpoles but without extreme specializations for either fossorial or aquatic life.     

Wild Animal Mycobacterial Isolates

Thirteen strains of mycobacteria isolated from deer and various species of wild birds were analysed by gas chromatography (GG) for cellular fatty acids and by thin-layer chromatography (TLG) for polar lipids. These strains were compared to reference strains of Mycobacterium avium, M. para tuberculosis and M. mal-moense. All the examined strains exhibited a generally similar fatty acid pattern characterized by relatively large amounts of hexadenca-noate (16:0), octadecenoate (18:1), octadecanoate (18:0) and 10-me-thyl-octadecanoate (tuberculostearic acid, 10-Me-18:0). Several additional acids were also generally present but in smaller amounts. By means of small but distinct differences in fatty acid composition, the wild animal isolates could be distinguished from both M. paratuber-culosis and M. malmoense but not from M. avium. The TLG polar lipid patterns on the other hand separated the wild animal isolates into 2 distinct groups of complex and simple polar lipid composition which corresponded to the morphologically smooth and rough types, respectively. The complex patterns of the smooth strains were comparable to those of the M. avium serovars whereas both the rough wild animal isolates and all the M. paratuber-culosis strains showed a simple pattern of polar lipids. Both fatty acid profiles and TLG polar lipid patterns support allocation of the wild animal isolates to the MAIS complex. Moreover, the 2 chemical techniques, particularly the GC procedure, are very useful for a more rapid and precise identification of the slow-growing wild animal mycobacterial isolates which have hitherto been characterized on basis of vague criteria.     

Esr,a second locus in the house mouse controlling esterase-5

Electrophoretic variation characterized by the presence (ES-5B⁺) or absence (ES-5B^–) of esterase-5B in the plasma of the house mouse has been observed. It is suggested that the expression of esterase-5B is controlled by an autosomal locus, Esr, linked to Ldr-1 on chromosome 6, in addition to the presumptive structural locus Es-5, which is located on chromosome 8. A gene order of Lyt-3-Esr-Ldr-1 was determined by two crosses.Supported by the Deutsche Forschungsgemeinschaft (SFB 46).This is communication No. 33 of a research program devoted to the investigation of cellular distribution and genetics of nonspecific esterases.     

Bacteriorhodopsin mutants containing single substitutions of serine or threonine residues are all active in proton translocation.

To study their role in proton translocation by bacteriorhodopsin, 22 serine and threonine residues presumed to be located within and near the border of the transmembrane segments have been individually replaced by alanine or valine, respectively. Thr-89 was substituted by alanine, valine, and aspartic acid, and Ser-141 by alanine and cysteine. Most of the mutants showed essentially wild-type phenotype with regard to chromophore regeneration and absorption spectrum. However, replacement of Thr-89 by Val and of Ser-141 by Cys caused striking blue shifts of the chromophore by 100 and 80 nm, respectively. All substitutions of Thr-89 regenerated the chromophore at least 10-fold faster with 13-cis retinal than with all-trans retinal. The substitutions at positions 89, 90, and 141 also showed abnormal dark-light adaptation, suggesting interactions between these residues and the retinylidene chromophore. Proton pumping measurements revealed 60-75% activity for mutants of Thr-46, -89, -90, -205, and Ser-226, and about 20% for Ser-141----Cys, whereas the remaining mutants showed normal pumping. Kinetic studies of the photocycle and of proton release and uptake for mutants in which proton pumping was reduced revealed generally little alterations. The reduced activity in several of these mutants is most likely due to a lower percentage of all-trans retinal in the light-adapted state. In the mutants Thr-46----Val and Ser-226----Ala the decay of the photointer-mediate M was significantly accelerated, indicating an interaction between these residues and Asp-96 which reprotonates the Schiff base. Our results show that no single serine or threonine residue is obligatory for proton pumping.     

The retinylidene Schiff base counterion in bacteriorhodopsin

Previous studies of bacteriorhodopsin have indicated interactions between Asp-85, Asp-212, Arg-82, and the retinylidene Schiff base. The counterion environment of the Schiff base has now been further investigated by using single and double mutants of the above amino acids. Chromophore regeneration from bacterioopsin proceeds to a normal extent in the presence of a single aspartate or glutamate residue at position 85 or 212, whereas replacement of both charged amino acids in the mutant Asp-85----Asn/Asp-212----Asn abolishes the binding of retinal. This indicates that a carboxylate group at either residue 85 or 212 is required as counterion for formation and for stabilization of the protonated Schiff base. Measurements of the pKa of the Schiff base reveal reductions of greater than 3.5 units for neutral single mutants of Asp-85 but only decreases of less than 1.2 units for corresponding substitutions of Asp-212, relative to the wild type. Substitutions of Asp-85 show large red shifts in the absorption spectrum that are partially reversible upon addition of anions, whereas mutants of Asp-212 display minor red shifts or blue shifts. We conclude, therefore, that Asp-85 is the retinylidene Schiff base counterion in wild-type bacteriorhodopsin. In the mutant Asp-85----Asn/Asp-212----Asn formation of a protonated Schiff base chromophore is restored in the presence of salts. The spectral properties of the double mutant are similar to those of the acid-purple form of bacteriorhodopsin. Upon addition of salts the folded structure of wild-type and mutant proteins can be stabilized at low pH in lipid/detergent micelles. The data indicate that exogenous anions serve as surrogate counterions to the protonated Schiff base, when the intrinsic counterions have been neutralized by mutation or by protonation.