Human bone marrow stromal cells express an osteoblastic phenotype in culture

Summary This study reports the selection and characterization of osteogenic precursors from human bone marrow which were isolated by two “clonings” and successive subculturing. These cell lines express alkaline phosphatase activity. Gel electrophoresis of [³H]-proline labeled cultures showed that the cloned cells produce only type I collagen. They synthetize osteocalcin and osteonectin. They respond to 1,25 dihydroxy vitamin D₃ by increasing osteocalcin synthesis and secretion, and to parathyroid hormone by increasing cyclic AMP synthesis. After the third subculture in the absence of β-glycerophosphate, these cell lines formed lots of clusters which exhibit high alkaline phosphatase activity and positive von Kossa staining. X-ray energy spectrum shows that these cells are surrounded by “budding” structures containing calcium and phosphorus with a ratio Ca:P identical to those of pure hydroxyapatite. This process was associated with⁴⁵Ca uptake into the cells. All these data support the selection of osteogenic cells which may be of considerable clinical importance.     

A novel and high-throughput approach to assess photosynthetic thermal tolerance of kelp using chlorophyll α fluorometry

Foundation seaweed species are experiencing widespread declines and localized extinctions due to increased instability of sea surface temperature. Characterizing temperature thresholds are useful for predicting patterns of change and identifying species most vulnerable to extremes. Existing methods for characterizing seaweed thermal tolerance produce diverse metrics and are often time-consuming, making comparisons between species and techniques difficult, hindering insight into global patterns of change. Using three kelp species, we adapted a high-throughput method – previously used in terrestrial plant thermal biology – for use on kelps. This method employs temperature-dependent fluorescence (T–F₀) curves under heating or cooling regimes to determine the critical temperature (T_crit) of photosystem II (PSII), i.e., the breakpoint between slow and fast rise fluorescence response to changing temperature, enabling rapid assays of photosynthetic thermal tolerance using a standardized metric. This method enables characterization of T_crit for up to 48 samples per two-hour assay, demonstrating the capacity of T–F₀ curves for high-throughput assays of thermal tolerance. Temperature-dependent fluorescence curves and their derived metric, T_crit, may offer a timely and powerful new method for the field of phycology, enabling characterization and comparison of photosynthetic thermal tolerance of seaweeds across many populations, species, and biomes.     

The gene coding for the α1 subunit of the skeletal dihydropyridine receptor (Cchl1a3=mdg) maps to mouse Chromosome 1 and human 1q32

Using both chromosomal in situ hybridization and molecular techniques, we report the genetic localization of the gene coding for the alpha 1 subunit of the skeletal slow Ca²⁺ current channel/DHP receptor gene (Cchl1a3) on human Chromosome (Chr) 1 (1q31–1q32 region) and on mouse Chr 1 region (F-G). On the basis of single-strand conformation polymorphism (SSCP-PCR) analysis in an interspecific backcross, we have determined that the Cchl1a3=mdg (muscular dysgenesis) locus is very closely linked to the myogenin (Myog) locus.     

Biosynthesis of Cephalosporin C

The superiority of d-methionine over l-methionine for stimulation of cephalosporin C synthesis in a crude medium was confirmed. The optimal level of dl-methionine was 0.5%. Methionine stimulates growth slightly but this is not thought to be the cause of the marked stimulation of antibiotic synthesis. Of a large number of sulfur compounds tested, only dl-methionine-dl-sulfoxide and S-methyl-l-cysteine showed considerable methionine-replacing activity. Lysine and α-aminoadipic acid were inactive.     

über die Natur der Hechtschen FÄden bei der Plasmolyse von Epidermiszellen der BlÄtter des SeegrasesZostera marina L.

Zusammenfassung Bei der Plasmolyse der Epidermiszellen des SeegrasesZostera marina L. löst sich der Protoplast nicht von der Zellwand. Der Volumenverlust der Zentralvakuole ist dabei grö\er als der Volumenverlust der Zelle, woraus eine Volumenzunahme, d. h. ein Quellen des Protoplasten, resultiert.Es quillt hauptsÄchlich eine Äu\ere Schicht des Cytoplasmas, die beim Beginn der Plasmolyse sichtbar wird und sich im weiteren Verlauf der Dinge wie ein vom inneren Protoplasten scharf abgegrenztes Zellorganell verhÄlt. In einem weiteren Stadium der Plasmolyse vakuolisiert dieses plastidenfreie Au\enplasma, und es bilden sich in ihm PlasmastrÄnge, die last immer vom plastidenhaltigen Innenplasma radial gegen die Zellwand gerichtet sind. Diese fÄdigen Strukturen im verquollenen und vakuolisierten Au\enplasma sind von den Hechtschen FÄden nicht zu unterscheiden.Bei der Deplasmolyse setzt zunÄchst ein erneutes Vakuolisieren in dem Teil des Au\enplasmas ein, der den Belag der Zellwand bildet; im weiteren Verlauf der Deplasmolyse geht die Vakuolisierung und die Quellung des Au\enplasnms zurück und das Zellorganell ist nicht mehr als selbstÄndige Struktur wahrzunehmen.Ob das Quellen und Vakuolisieren des Au\enplasmas einer Konkavoder einer Konvexplasmolyse Ähnlich wird, ist von der Art des verwendeten Plasmolytikums abhÄngig.Es kann noch nichts darüber ausgesagt werden, ob das plastidenfreie Au\enplasma ein verquollenes vielschichtiges Plasmalemma ist oder ob auch Elemente des Mesoplasmas beteiligt sind.     

Biochemical characterization and novel isolation of pure estrogen receptor hormone-binding domain

Biologically active, mouse estrogen receptor hormone-binding domain (residues 313–599) overexpressed in Escherichia coli was purified to apparent homogeneity as a single component with a molecular mass of 32.831 kDa determined by electrospray ionization mass spectrometry, and was identical to the mass predicted from the amino acid sequence. The intact domain was isolated using a novel, rapid purification scheme without recourse to any chromatographic process. Pure ERhbd maintained both high affinity estradiol binding (at optimum pH 8.0) and specificity for estrogens and anti-estrogens. The steroid-binding domain sedimented as a 4S component in the presence or absence of bound [³H]estradiol and at 2S in the presence of urea. The molecular mass of the 4S steroid unoccupied ERhbd (from dynamic light scattering) was 72 kDa, suggesting that the pure, unlabelled ERhbd formed homodimers. Steroid-labelled ERhbd electrofocussed as a single, acidic component at a pI of 5.6. Binding of ERhbd to [³H]estradiol was unaffected by Ca²⁺ and Mg²⁺ ions up to 1 mM but was significantly inhibited by Zn²⁺ ions at concentrations above 10 μM, an effect reversed by EDTA.     

Human and animal mesenchymal progenitor cells from bone marrow: Identification of serum for optimal selection and proliferation

Summary An undifferentiated subset of cells within the stromal cell population of bone marrow in postnatal mammals retains the capacity to differentiate along osteogenic, adipogenic, fibroblastic, and chondrogenic lines. These cells, which are referred to as mesenchymal stem cells (MSCs), can be maintainedin vitro and expanded in number through a process of subculturing. MSCs are maintained in culture in medium supplemented with 10% fetal bovine serum (FBS). It is believed that certain, as yet unidentified, serum components play critical roles in the attachment and proliferation of MSCs. Commercially available FBS is poorly characterized and may vary in composition and quality from lot to lot. This study describes a method for the selection of lots of FBS that best support maintenance of the undifferentiated state, mitotic expansion of MSCsin vitro, and retention of multilineage developmental potential in response to appropriate cues.