Effects of nucleotides and divalent cations on phospholipase activity in Saccharomyces cerevisiae

Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 M. The inhibition by nucleotides in low concentrations is enhanced by divalent cations.     

Expression of acetylcholinesterase during visual system development in Drosophila

As in other insects acetylcholine (ACh) and acetylcholinesterase (AChE) function in synaptic transmission in the central nervous system of Drosophila. Studies on flies mutant for AChE indicate that in addition to its synaptic function of inactivating acetylcholine, this neural enzyme is required for normal development of the nervous system (J.C. Hall, S.N. Alahiotis, D.A. Strumpf, and K. White, 1980, Genetics 96, 939-965; R.J. Greenspan, J.A. Finn, and J.C. Hall, 1980, J. Comp. Neurol. 189, 741-774). In order to understand what role AChE may play in neural development, it is necessary to know, in detail, where and when the enzyme appears. The use of monoclonal antibodies to localize AChE in the developing visual system of wild type Drosophila has yielded the novel observation that AChE appears in photoreceptor (retinula) cells 4-6 hr after they differentiate and 3 to 4 days before they are functional. Three days later the staining in the cell body of these cells is reduced. Because retinula cells have no functional connections at the time when AChE is first detected, AChE can not be performing its standard synaptic function. Subsequent to the reduction of AChE in the retinula cells, midway through the pupal stage, the enzyme accumulates rapidly in the neuropils of the optic lobes of the brain. Thus, there is a biphasic accumulation of AChE in the developing visual system with the enzyme initially being expressed in the retinula cells and accumulating later in the optic lobes.     

Schwermetalle in Organen und Federn von Graureihern (Ardea cinerea) und Kormoranen (Phalacrocorax carbo)

Zusammenfassung Mittels der Atomabsorptionsspektroskopie wurden Lebern, Nieren und Federn von Graureihern und von diesjährigen Kormoranen auf Cadmium und Blei untersucht.Cadmium war in Geweben der Kormorane höher konzentriert als in gleichaltrigen Graureihern (Leber 0,063 bzw. 0,039, Niere 0,113 bzw. 0.104 mg/kg Frischmasse; Federn 0,077 bzw. 0,025 mg/kg Trockenmasse). Dies könnte auf unterschiedliche Nahrung oder unterschiedliche physiologische Situation der Vögel zurückzuführen sein. Als Maximum wurden in der Niere eines Kormorans 0,375 mg/kg gemessen. Bei den Graureihern konnte in Lebern und Nieren eine Altersakkumulation erkannt werden. Blei war in den Geweben beider Arten unterschiedlich hoch konzentriert. Kormorane enthielten in Lebern 0,124 und in Nieren 0,147 mg/kg Frischmasse sowie in Federn 0,442 mg/kg Trockenmasse, Graureiher 0,110, 0,157 bzw. 0,739 mg/kg. Die höchsten Konzentrationen wurden in Federn gemessen und betrugen bei einem Graureiher 4,525 mg/kg. Eine Altersakkumulation konnte bei Graureihern in Lebern nachgewiesen werden. Zusammenhänge zwischen Feder- und Organbelastungen wurden nur bei diesjährigen Graureiher- erkannt: Federcadmium und Lebercadmium korrelierten positiv miteinander.

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Heavy metals in tissue and feathers of Grey Herons (Ardea cinerea) and Cormorants (Phalacrocorax carbo sinensis)

Summary The livers, kidneys and feathers of 40 Grey Herons and 20 Cormorants were investigated by AAS to determine the extent of contamination with cadmium and lead. The birds had been shot in autumn 1979–1986 in Schleswig-Holstein. All results are given in mg/kg (ppm) wet mass (liver, kidney) or dry weight (feather). On the average, the contamination by cadmium in the livers (0.063), kidneys (0.113) and feathers (0.077) was higher in Cormorants than in Grey Herons (0.039, 0.104 and 0.025). These differences may be the result of different food or physiology. The livers and kidneys of young Grey Herons contained less cadmium than the tissue of older birds. The feathers of male Grey Herons contained more cadmium than feathers of females do. This was also the case in kidneys of male Cormorants as compared to the females. Cadmium values in livers and kidneys were positive correlated. No general tendency was detectable in regards to lead contamination. The results concerning Cormorants were 0.124 (liver), 0.147 (kidney), 0.442 (feather) and concerning Grey Herons 0.110, 0.157 and 0.739. The livers of old Grey Herons were more highly contaminated by lead than livers of young ones. The feathers of male Herons contained two times more lead than the feathers of females do.In general, a concentration of heavy metals in feathers does not indicate a contamination of livers or kidneys. A correlation between the values in feathers and tissue was evident only in one case, where a positive correlation was found between feather- and liver cadmium in young male Grey Herons.

     

Core substructure in Mastigocladus laminosus phycobilisomes

A native high molecular complex (M_r 850000) containing about 50% of the allphycocyanin of the phycobilisome but lacking allophycocyanin B was separated from isolated phycobilisomes by gel electrophoresis. It was designated AP_CM since the large linker polypeptide L_CM was exclusively localized in this complex. The complex exhibited a ?196°C fluorescence emission maximum at 673 nm (671 nm at 25°C). In addition, a core complex (designated AP_C, M_r≥1000000) consisting of both AP_CM and AP 680 was isolated by combined gel filtration and linear gradient centrifugation. At 25°C this complex showed dual emission peaks at 670 and 680 nm demonstrating functional independence of the terminal emitters. A complex similar to AP_CM can be isolated from phycobilisomes of Anabaena variabilis. This is evidence that AP_CM is the constitutive center of the tricylindrical core of hemidiscoidal cyanobacterial phycobilisomes. Two models summarizing the structural and functional consequences of the results are presented in the discussion.     

Two auditory filter systems determine the calling behavior of the fire-bellied toad: a behavioral and neurophysiological characterization

Summary Male fire-bellied toads,Bombina bombina, are stimulated into calling by conspecific mating calls. They tend to synchronize their activity with other calling individuals, which leads to antiphonal calling. Behavioral physiological experiments revealed the existence of two different auditory filter systems which influence this acoustic behavior. One filter system is tuned to the recognition of conspecific mating calls, the other is part of a circuit that controls an acoustic jamming avoidance reaction. The two filter systems differ in several properties: filter bandwidth, threshold, and time constant. Neurophysiological recordings in the midbrain and the thalamus show that the filter characteristics can be explained by the coding properties of auditory neurons in these two brain nuclei.     

Recovery of metals from acid waste water by Cyanidium caldarium

Summary Cyanidium caldarium grows in acid water obtained from a bacterial leaching procedure and the alga is capable of precipitating metals from the solution. This study demonstrates that changes in culture and oxidation-reduction conditions may result in a different bioaccumulation of metals.     

Partial purification and characterization of a cellular protein that binds to the SV40 core origin of DNA replication

A monkey cell factor that interacts specifically with double- and single-stranded DNA sequences in the early domain of the simian virus 40 (SV40) core origin of replication was identified using gel-retention assays. The protein was enriched over 1200-fold using ion-exchange and affinity chromatography on single-strand DNA cellulose. Binding of protein to mutant origin DNA restriction fragments was correlated with replication activity of the mutant DNAs. Exonuclease footprint experiments on single-stranded DNA revealed prominent pause sites in the early domain of the core origin. The results suggest that this cellular protein may be involved in SV40 DNA replication.     

Orientation of Dunnocks (Prunella modularis) at Sunset

To find out the relative importance of the geomagnetic and solar cues for the orientation at the time of sunset, dunnocks were tested outdoors during the spring migration periods of 1982 and 1983. Experimental magnetic fields were produced by Helmholtz coils. In the various magnetic conditions, the following results were obtained:

• 1 In the local geomagnetic field, the dunnocks oriented in a seasonally appropriate northerly direction.
• 2 In a magnetic field the north of which was shifted 120° clock-wise to ESE, the birds showed a corresponding shift in their orientation.
• 3 In a vertical magnetic field without meaningful directional information, birds previously tested in either the local geomagnetic field or the shifted magnetic field now displayed axially bimodal orientation, with the axes of the two groups differing.

These findings indicate that for migratory dunnocks, the magnetic field plays a dominant role in determining their orientation at the time of sunset, and that magnetic information may affect the dunnocks' response to other directional, presumably solar cues as well.