Non-destructive assay systems for detection of β-glucuronidase activity in higher plants

β-glucuronidase (GUS) can be qualitatively assayed in seedlings and fully grown plants without injury or irreversible damage by short term incubations in X-gluc or by spraying 4-MUG.     

Trypsin activity in the small intestine of rats after application of copper and zinc

In vivo experiments with Sprague-Dawley rats were conducted in order to explore the influence of Cu²⁺, Zn²⁺ as well as of the combinations of both on the activity of trypsin. The solutions of the trace elements were given per os, the animals were killed 30 min after the applications, and the activity of trypsin was determined in the juice of the small intestine by usingN ^α-benzoyl-L-arginine-p-nitroanilide (L-BAPA) as the substrate. The activity of trypsin depends on the concentration of the trace elements. When Cu²⁺ ions are applied, there is a minimum activity at 10⁻⁵ mol Cu²⁺/L and a maximum at 10⁻⁴ mol Cu²⁺/L. When giving Zn²⁺ ions, a minimum of trypsin activity is found at 10⁻⁵ mol Zn²⁺/L and a maximum at 5×10⁻⁶ mol Zn²⁺/L. On the whole, the trypsin activity is lower when the Cu²⁺/Zn²⁺ combinations are applied compared to the addition of the single trace elements. On principle, a good conformity of the in vivo results was found with in vitro results.     

Ribosomes in thiostrepton-resistant mutants of Bacillus megaterium lacking a single 50 S subunit protein.

A protein required for the binding of thiostrepton to ribosomes of Bacillus megaterium has been purified and further characterized by immunological techniques. This protein, which does not bind the drug off the ribosome, is serologically-homologous to Escherichia coli ribosomal protein L11 and is designated BM-L11. Ribosomes from certain thiostrepton-resistant mutants of B. megaterium appear to be totally devoid of protein BM-L11 as judged by modified immunoelectrophoresis. Such ribosomes are significantly less sensitive than those from wild-type organisms to the action of thiostrepton in vitro but retain substantial protein synthetic activity. Re-addition of protein BM-L11 to ribosomes from the mutants restores them to wild-type levels of activity and thiostrepton sensitivity. Thus ribosomal protein BM-L11 is involved not only in binding thiostrepton but also in determining the thiostrepton phenotype.     

Protein synthesis and transport by the rat choroid plexus and ependyma

Summary Light (LM-ARG) and electron microscope (EM-ARG) autoradiographs were prepared from immature rat choroid plexus and ependyma at 5, 10, 30, and 60 min and 16 h following intraperitoneal administration of [³H]- labeled amino acid mixtures. Intracellular protein synthesis and transport were ascertained in lateral and fourth ventricle choroid plexus epithelium by quantitative EM-ARG at the several post-injection intervals. ARG were also prepared from choroid plexuses cultured for one day, pulse labeled for one hour and reincubated for various periods in nonradioactive media. Significant labeling of both attached and free apical protrusions (blebs) was observed in both choroid plexus and ependyma in vivo and in choroid plexus in vitro. This phenomenon was interpreted as a physiologically significant mechanism for protein transport (apocrine secretion) by epithelia into the cerebrospinal fluid (CSF).This study was supported in part by N.I.H. Research Grant NS 12906     

Licht- und elektronenmikroskopische Untersuchungen am Radulakomplex und zur Radulabildung vonBiomphalaria glabrata Say (=Australorbis gl.) (Gastropoda,Basommatophora)

Zusammenfassung Biomphalaria glabrata besitzt eine Prä- und eine Postradulatasche, sowie eine Sperrkutikula. Das Radulapolster besteht nicht aus Knorpel, sondern aus großen Zellen, die durch zahlreiche Vesikel, Mitochondrien, sowie durch peripher liegende Muskelfasern gekennzeichnet sind, während andere Zellen große Mengen Glykogen speichern. Die Odontoblasten sind charakterisiert durch ungewöhnlich lange Mikrovilli, die bis in die neugebildeten Radulazähne ragen. Die Zahnbildung beginnt über den hinteren Odontoblasten, die zunächst nur kurze Mikrovilli aufweisen. Das Aufrichten eines neugebildeten Zahns dürfte dadurch zustande kommen, daß die Mikrovilli länger werden. Zwischen den Mikrovilli befindet sich elektronendichtes Material, in dem Mikrofibrillen entstehen; diese dürften Chitin enthalten. Die Verflechtung der Mikrofibrillenbündel im ausgebildeten Zahn entspricht offensichtlich der komplizierten Anordnung der langen Mikrovilli während der Zahnbildung. Die Mikrovilli werden schließlich in den neugebildeten Zahn und die Radulamembran integriert. Mehrere Odontoblasten sezernieren gemeinsam einen Radulazahn. Die Radulamembran wird vorwiegend oder ausschließlich vom vordersten Odontoblasten sezerniert. Die Zellen des Deckepithels umschließen die Radulazähne; die sogenannte Sekrethöhle dürfte ein Artefakt sein. Zwischen Deckepithel und Zahn befindet sich elektronendichtes Material, das dem Zahn nicht aufgelagert wird, sondern in die Zähne eingelagert werden dürfte. Die Zellen des Basalepithels zeigen starke sekretorische Aktivität; die Sekrete dürften in Radulamembran und -zähne eingelagert werden.

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Light and electron microscopic investigations on the radula complex and radula formation ofBiomphalaria glabrata say (=Australorbis gl.) (Gastropoda, Basommatophora)

Summary Biomphalaria (Australorbis) glabrata has a preradular as well as a postradular pocket and a collostyle hood. The odontophore cartilage does not consist of cartilage, but of cells which are characterized by numerous vesicles, mitochondria, and muscle fibres in the periphery; other cells contain large amounts of glycogen. The odontoblasts are characterized by unusually long microvilli which reach into the newly formed radula teeth. The formation of a tooth begins above the posterior odontoblast which has at first only short microvilli. The tooth seems to be raised by the extension of these microvilli. Microfibrils are formed in the electron dense material which is present in the small space between the microvilli; probably these microfibrils contain chitin. Obviously the interlacing of the bundles of microfibrils in a tooth corresponds with the complex arrangement of the long microvilli during formation of the tooth. Finally the microvilli are integrated into the newly formed tooth and radular membrane. Several odontoblasts join to form a single tooth. The radular membrane is secreted mainly or exclusively by the most anterior odontoblast. The cells of the superior epithelium surround the radula teeth. The so-called secretion cavity seems to be an artifact. Electron dense material is present between teeth and superior epithelium which is not apposed to but seems to be integrated into the teeth. The cells of the inferior epithelium show considerable secretory activity; the secretions seem to be incorporated into radular teeth and membrane.

     

Enzymatic dissection of embryonic cell adhesive mechanisms: II. Developmental regulation of an endogenous adhesive system in the chick neural retina

Previous studies have demonstrated the presence of two functionally distinct intercellular adhesive systems operating among embryonic chick neural retina cells. These systems differ in their proteolytic sensitivity, protection by calcium against proteolysis, dependence on calcium for function, and in vitro morphogenetic potential. In this report we demonstrate that functional expression of the calcium-dependent adhesive system of embryonic chick neural retina cells is developmentally regulated between Days 7 and 16 of development, whereas the calcium-independent adhesive system is not. Age-dependent changes are described in terms of the ability to produce adhesive-competent cells bearing the calcium-dependent adhesive system and in terms of the responses of these cells during aggregation to perturbations with various drugs. Enzyme and ion combinations other than calcium and typsin are shown to yield calcium-dependent adhesive-competent cells. We also describe the protective effect of calcium on the histological and ultrastructural organization of trypsinized embryonic neural retina tissue. The possible role of the calcium-dependent adhesive system in retinal development is discussed.     

Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

More “diffusible” auxin is received from nonsterile than from sterile corn coleoptile tips. An artificial reinfection of sterile coleoptiles with epiphytic, IAA-producing bacteria strains does, a superinfection of nonsterile coleoptiles does not increase the auxin amount. The difference between sterile and nonsterile tips persists if diffusion from the coleoptile surface is excluded by covering the surface with a paraffin layer. The greater the distance from the apex, the higher becomes the superiority of nonsterile tips. An artificial bacterial contamination of the contact face between tip and receiver agar block, or addition of glucose and tryptophan to the agar block, do not influence the received auxin amount. Consequently the additional, bacteria-produced auxin delivered by the nonsterile tip is not produced at the cut surface or in the agar but is present in the tissues of the coleoptile tip.