Peptide alcohols as promoters of nitrate and ammonium ion uptake in plants

Several aryl-carbamoyl dipeptide alcohols increased the uptake of nitrate and ammonium ions into corn root segments by up to 50% and 90%, respectively. The most effective one was N-carbobenzoxy-l-prolyl-l-valinol. Foliar application of this compound to underfertilized corn plants caused an increase in the rate of plant growth in the greenhouse and provided modest (6-10%) corn yield increases in field tests in Delaware.     

The articular disc of the hand.

The carpal articular disc have been studied in serial sectioned embryonal and fetal hands. It can be concluded that the articular disc is an extensive fibrous system that comes from the ulnar edge of the distal end of the radius and reaches, bordered by the deep layer of the antebrachial fascia, the base of metacarpal V. In this course, insertions take place into the ulnar aspect of the head of the ulna, into the ulnar styloid process and into the ulnar carpals. Emphasis has been laid upon the fact that the sheath of the m. extensor carpi ulnaris tendon is part of the fibrous system of the disc. The positions of the dorsal tendons seen with respect to the fascial implicate a mutual shift during pronation and supination of the hand. The relations between the so-called ligamentum subcruentum and prestyloid recess have been established, the presence of cartilaginous primordia in the developing dis has been discussed. We come to the conclusion that the evidence for drawing a parallel between phylogenetic and human embryological phenomena is still insufficient. In this connection we have stressed the modus of development of the pisotriquetral joint space.     

Human alveolar macrophage fibronectin: synthesis, secretion, and ultrastructural localization during gelatin-coated latex particle binding

Human pulmonary alveolar macrophages synthesized and secreted several characteristic high molecular weight proteins for at least 7 d in vitro. Immunoprecipitates of medium and cell lysates from metabolically labeled cultures with specific anti-human plasma fibronectin IgG contained one major labeled polypeptide of molecular weight 440,000 (unreduced) or 220,000 (reduced). An identical polypeptide in conditioned medium from radiolabeled macrophages bound specifically to gelatin-Sepharose, demonstrating that alveolar macrophages synthesized and secreted a molecule immunologically and functionally similar to fibronectin. Fibronectin was the major newly synthesized and secreted polypeptide of freshly harvested alveolar macrophages. Pulse-chase experiments revealed that newly synthesized fibronectin was rapidly secreted into medium, approximately 50 percent appearing by 1 h and 80 percent by 8 h. Immunoperoxidase staining using antifibronectin F(ab’)(2)-peroxidase conjugates revealed the majority of immunoreactive fibronectin to be intracellular, localized to endoplasmic reticulum and Golgi apparatus. No extracellular matrix fibronectin was visualized, and cell surface staining was rarely seen, usually appearing only at sites where cells were closely apposed and not at sites of macrophage-substrate attachment. Similar immunostaining of fibroblast cultures revealed cell surface-associated fibrillar fibronectin. Ultrastructural localization of fibronectin during binding and phagocytosis of gelatin-coated and plain latex particles revealed fibronectin only on gelatin-latex beads and at their cell binding sites. Neigher plain latex beads nor their cell membrane binding sites stained for fibronectin. These results demonstrate that fibronectin is a major product of human alveolar macrophages, is rapidly secreted, and is localized at cell membrane binding sites for gelatin-coated particles. In view of the known binding properties of fibronectin, it may serve as an endogenous opsonic factor promoting the binding of staphylococcus, denatured collagen, fibrin, or other macromolecules to macrophages in the lower respiratory tract.     

Excretion of Sugars by Chlorella Species Capable and Incapable of Symbiosis with Hydra viridis

The excretion of some sugars (maltose, glucose, and glucose-6-phosphate) was studied at pH 2.5–6.0 in 38 strains of Chlorella belonging to 15 species of which 7 are capable and 8 incapable of symbiosis with Hydra viridis. A high rate of maltose excretion below pH 4.0 (Cernichiari et al., 1969) was found only in C. vulgaris (non-symbiotic) and C. mirabilis (non-symbiotic). The other Chlorella species are characterized by quite different patterns of sugar excretion. C. spec. (= “C. paramecii”; symbiotic) excretes very high amounts of maltose in the whole range from pH 2.5–6.0. C. kessleri (symbiotic), C. luteoviridis (symbiotic), and C. fusca var. fusca (non-symbiotic) show a predominant excretion of glucose-6-phosphate from pH 2.5–6.0. Some strains also exhibit a high excretion of glucose above pH 4.0 (C. spec. = “C. paramecii”) or below pH 3.0 (C. fusca var. vacuolata). Several species, e.g. C. saccharophila var. saccharophila (symbiotic), C. sorokiniana (non-symbiotic), and C. protothecoides (symbiotic), excrete only very small amounts of sugars. There is no obvious correlation between sugar excretion and the ability or inability of the Chlorella species to form stable symbioses with Hydra viridis.     

Phylogenetic screening of the human genome: identification of differentially hybridizing repetitive sequence families

The phi-screen, a method of phylogenetic screening, can be employed to detect repetitive sequence families that differentially hybridize between closely related species. Such differences may involve sequence divergence or variations in copy number, including total presence versus absence of a family of repeated DNA. We present the results of a phi-screen comparing the human genome to that of the prosimian, Galago crassicaudatus. Three human repetitive families that are divergent or not present in galago have been detected. One of these families is described in detail; it is similar among the anthropoids but is present in a lower copy number and/or divergent form in prosimians. The family is clearly related to the transposon-like human element (THE) described by Paulson et al. (1985). THEs have long terminal repeats reminiscent of retroviruses but are unique in that they have no sequence similarity to known mammalian retroviruses. The sequence of a solo long terminal repeat, found unassociated with THE internal sequence, is presented. This family member, THE p2, is bordered by a 5-bp target-site repeat and is interrupted by the insertion of an Alu element. A solo THE element sequenced by Wiginton et al. (1986) contains an insertion of Alu at precisely the same position as does THE p2.      

DNA divergence in and around the alcohol dehydrogenase locus in five closely related species of Hawaiian Drosophila

The alcohol dehydrogenase (Adh) region from five planitibia subgroup species of Hawaiian picture-wing Drosophila has been cloned. A total of 15 kb of DNA in and around the Adh gene has been compared among the five species. Genetic distances were calculated to determine evolutionary relationships. These distances agree with previous distances determined by protein polymorphism and DNA hybridization techniques and can be interpreted in terms of specific island colonization and speciation (founder) events over the past 5 Myr. Examination of the restriction maps of the cloned Adh region from the five species shows many instances of small deletions, insertion of a transposable element in D. heteroneura, and the existence of a highly variable region on the 3' side of the Adh gene. Clustering relationships and rates of DNA change are calculated and compared with the relationship found for other species of Drosophila.