Defensive behaviour and its inheritance in the anabantoid fish, Macropodus opercularis and Macropodus opercularis concolor

In this preliminary study defense behaviour patterns (fear responses) are described in two closely related, behaviourally different inbred labyrinth fish subspecies and in their F₁ generation. The subspecies M. opercularis (characterized briefly by “active escape”) and M. opercularis concolor (characterized by “passive escape”) showed specific differences in the manifestation of certain defense behaviour patterns. In the F₁ hybrid generation dominance and overdominance of M. opercularis was found in most defense behaviour patterns. Analysing the frequencies and sequences of movement patterns it could be shown that defensive behaviour is not a random or entirely “plastic” process but that there is sequential linkage between the patterns and they form characteristic clusters. Our results suggest that manifestations of different patterns are under genetic control and presumably, genetic determination of certain patterns is not very complex. Attempts were made to determine whole brain noradrenaline, serotonine and dopamine levels of the two subspecies and a significant difference was found in the noradrenaline content.     

Termination of incubation in doves: Influence of egg fertility and absence of mate

The present experiments examine the role of the eggs, the mate, and hormonal state in the termination of incubation by ring doves. Doves given either infertile eggs or newly laid fertile eggs at midincubation did not prolong incubation significantly beyond that observed in doves with hatching eggs. However, there was substantial lack of synchrony between mates in the experimental groups. Half the experimental females laid new eggs, often without interrupting incubation. To clarify the role of the mate in maintaining sitting, pairs were separated on Days 1, 5, or 10 of incubation. Initially birds in each group incubated alone throughout the day. The decline in sitting was more rapid in pairs which had been separated early in incubation. To explore the hormonal correlates of the termination of incubation, mates were separated on the 10th day of incubation and observed until they quit sitting. At this time, males showed substantial crop development. Females had little crop development and large preovulatory folliclels, indicating readiness to lay new eggs despite the absence of the male. We conclude that the termination of incubation by parent doves is delayed by the presence of the mate and this, in turn, prevents follicular development and recycling by the female. Cues from the offspring are important in synchronizing the behavior of the parents and also in preventing a new breeding cycle.     

A Guide to the Metabolic Pathways and Function of Metabolites Observed in Human Brain 1H Magnetic Resonance Spectra

The current knowledge of the normal biochemistry of compounds that give rise to resonances in human brain proton magnetic resonance spectra measureable at readily available field strengths (i.e. ≤3 T) is reviewed. Molecules covered include myo- and scyllo-inositol, glycerophospho- and phospho-choline and choline, creatine and phosphocreatine, N-acetylaspartate, N-acetylaspartylglutamate, glutamate, glutamine, γ-aminobutyrate, glucose, glutathione and lactate. The factors which influence changes in the levels of these compounds are discussed. As most proton resonances in the brain at low field are derived from a combination of moieties whose biochemistry is complex and interrelated, an understanding of the mechanisms underlying why these species change is crucial to meaningful interpretation of human brain spectra.     

Electrically silent potassium channel subunits from human lens epithelium

We describe the cloning and characterization of the first humanmembers, hKv9.1 and hKv9.3, of the electrically silentdelayed-rectifying-like K⁺ channelsubfamily. Their modulatory effects on the electrically activesubfamily member hKv2.1 are also quantified. The hKv9K⁺ channels were isolated from ahuman lens epithelium cDNA library, but both hKv9.1 mRNA and hKv9.3mRNA were found to coexist with the mRNA for hKv2.1 in a large numberof human tissues. The hKv9.1 gene is composed of a minimum of fiveexons, with at least two alternatively spliced exons in the5'-untranslated region (UTR). In contrast, the hKv9.3 gene isintronless across the coding region, 3'-UTR, and all of theanalyzed 5'-UTR. Radiation hybrid mapping localized the hKv9.1gene to 20q12 and the hKv9.3 gene to 2p24. Each electrically silentsubunit, when coexpressed with hKv2.l, slows deactivation andinactivation compared with hKv2.1 expressed alone. In addition, eachresults in an increment in the single channel conductance.

     

Continuous dental eruption identifies Sts 5 as the developmentally oldest fossil hominin and informs the taxonomy of Australopithecus africanus

The relatively small Australopithecus africanus specimen Sts 5 has figured prominently in taxonomic debates, and the determination of this specimen as a young male or an elderly female has the potential to offer a great deal of resolution on this question. Sts 5 has been argued to be either a small, immature male or a mature female based on a variety of characters.     

Dye Transfer Between Cells of the Lens

Dye transfer between lens fiber cells and between lens epithelial cells and underlying fiber cells was studied using a wide dynamic range-cooled CCD camera, H₂O immersion objectives and image analysis techniques. Each lens was decapsulated by a new technique which leaves the epithelial cells adherent to the lens fiber mass. Lucifer Yellow CH was injected into either single epithelial cells or single fiber cells using the standard whole cell configuration of the patch voltage clamp technique. The results demonstrate extensive dye communication between fiber cells at the lens posterior surface, anterior surface, and equatorial surface. Dye transfer between deep fiber cells was also observed. Dye transfer between ≈10% of epithelial cells and their underlying fiber cells was apparent when care was taken to yield wide dynamic range images. This was required because the relatively high concentration of dye in the epithelial cell masks the presence of much lower dye concentrations in the underlying fiber cell. A mathematical model which includes dye concentration, time, and spatial spread suggests that those epithelial cells that are coupled to an underlying fiber cell are about as well dye coupled as the epithelial cells themselves. The relatively low dye concentration in a fiber cell is due to its larger volume and diffusion of the dye along the axis of the fiber away from the fiber/epithelial junction. Received: 14 September 1995/Revised: 13 November 1995