Picosecond structural dynamics of myoglobin following photodissociation of carbon monoxide as revealed by ultraviolet time-resolved resonance Raman spectroscopy

Picosecond protein dynamics of myoglobin in response to structural changes in heme upon CO dissociation were observed in a site-specific fashion for the first time using time-resolved UV resonance Raman spectroscopy. Transient UV resonance Raman spectra showed several phases of intensity changes in both tryptophan and tyrosine Raman bands. Five picoseconds after dissociation, the W18, W16, and W3 bands of tryptophan residues and the Y8a band of tyrosine residues decreased in intensity, followed by recovery of the Y8a band intensity in hundreds of picoseconds and recovery of the tryptophan bands in nanoseconds. These spectral changes suggest that the change in heme structure impulsively drives concerted movement of the EF helical section and that rearrangements toward a deoxy structure occur in the heme vicinity and in the A helix within a time frame of sub-nanoseconds to nanoseconds.     

Intracytoplasmic sperm injection with mouse spermatozoa preserved without freezing for six months can lead to full-term development

Preservation of mammalian spermatozoa now plays an important role in fertility treatment, in generating hybrid animals, and in protecting endangered or extinct species. To date, the most common method of sperm preservation is freezing in liquid nitrogen (LN(2)). However, this method requires constant supplementation of the LN(2) and also involves some safety issues in transporting LN(2). Here we describe a new sperm preservation method that does not involve freezing. Mouse spermatozoa were cultured in four basic media (HEPES-CZB, potassium simplex optimization medium with amino acids [KSOMaa], K(+)-rich nuclear isolation medium [NIM], and PBS) with or without 10% bovine serum albumin (BSA) or 15% Ficoll as a protectant, and preserved in a refrigerator for up to 6 mo. These preserved sperm were then injected into fresh oocytes and cultured to the blastocyst stage in vitro or transferred into recipient females to demonstrate their genetic integrity. The results of sperm preservation for 1 mo suggested that NIM and PBS were better media than HEPES-CZB or KSOMaa and that BSA and Ficoll could improve either blastocyst or full-term development. Surprisingly, 18 pups were obtained using spermatozoa stored in these media for 6 mo. Moreover, this new method allowed easy production of healthy offspring even after transport of spermatozoa between two countries by aircraft at room temperature. In conclusion, this method allows for easy long-term preservation of mouse spermatozoa in a simple, modified medium at refrigerator temperature with very low cost and wide application.     

No inhibitory effects of gestrinone and medroxyprogesterone acetate on the estrogen production by ovaries of hypophysectomized rats stimulated by gonadotropins.

The in vivo effects of gestrinone (R2323) and medroxyprogesterone acetate (MPA) on the estrogen production by rat ovaries were investigated. Hypophysectomized immature female rats treated with 2.5 or 5 IU of pregnant mare serum gonadotropin (PMS) were daily given vehicle only, gestrinone (0.5 mg/kg body weight) or MPA (10 mg/kg body weight), and the activities of 3 beta-hydroxysteroid dehydrogenase, 17 alpha-hydroxylase, 17, 20-lyase, 17 beta-hydroxysteroid dehydrogenase and aromatase in ovaries of these rats were measured. Gestrinone suppressed the 3 beta-hydroxysteroid dehydrogenase activity and increased activities of 17 alpha-hydroxylase, 17, 20-lyase and aromatase in ovaries stimulated by 5 IU of PMS, while MPA suppressed activities of 17 alpha-hydroxylase and aromatase in these ovaries. On the other hand, the aromatase activity in ovaries stimulated by 2.5 IU of PMS was suppressed by gestrinone and increased by MPA, and neither gestrinone nor MPA affected the production of aromatizable androgens from progesterone by these ovaries. Thus, gestrinone and MPA administrated in vivo showed divergent influences on steroidogenic enzyme activities in ovaries, but they did not affect the serum concentration of estradiol-17 beta. The present results suggest that neither gestrinone nor MPA reduced estrogen production by the rat ovary under the gonadotropin stimulation although they influenced some process of its steroidogenesis.     

Trace 5-Methylaminomethyl-2-selenouridine in bovine tRNA and the selenouridine synthase activity in bovine liver

We measured the amount of Se in bovine liver tRNA. tRNA was chromatographed on a BD-cellulose column and Se-rich tRNA was eluted from the column in front of a main tRNA peak. There was 0.3 mmol Se/mol of tRNA and this level is about one tenth that of Escherichia coli tRNA. This suggests the presence of an enzyme that modifies tRNA with Se in bovine liver. We isolated the activity of this enzyme (selenouridine synthase) by chromatography of bovine liver extracts on a DEAE-cellulose column. ATP and selenophosphate synthetase, as well as selenouridine synthase and tRNA, were necessary for the reaction. ⁷⁵Se was used to label the reaction products, which were analyzed by TLC after digestion with ribonuclease T₂. The position of the ⁷⁵ Se-nucleotide on a TLC plate was identical to that of the Se-nucleotide, 5-methylaminomethyl-2-seleno-Up, prepared from ⁷⁵Se-tRNA in E. coli.     

Phosphorylation of bovine brain 81-kDa acidic calmodulin binding protein (ACAMP-81) in vitro.

We found a novel 81-kDa acidic protein (ACAMP-81) in the bovine brain membrane fraction, which bound to calmodulin in a Ca(2+)-dependent manner. The present study reveals physicochemical properties and phosphorylation of this protein with various protein kinases in vitro. The Stokes radius and sedimentation coefficient were calculated to be 52 A and 2.05 S, respectively, suggesting that the structure of ACAMP-81 is highly elongated. Purified Ca2+/phospholipid-dependent protein kinase (protein kinase C), cAMP-dependent protein kinase, and Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II) catalyzed the incorporation of 1.46, 0.72, and 0.44 mol of phosphate/mol of ACAMP-81, respectively. The amino acid residues of ACAMP-81 phosphorylated by either protein kinase C or cAMP-dependent protein kinase were almost exclusively on serine. Sequential phosphorylation of ACAMP-81 by cAMP-dependent protein kinase and protein kinase C resulted in the additional incorporation of 1.15 mol of [32P]phosphate into ACAMP-81. Comparison of phosphopeptide maps of ACAMP-81 phosphorylated by each kinase revealed that there are two classes of phosphorylatable polypeptide, one is phosphorylatable by both protein kinases which contained two polypeptides and the others are specific sites for protein kinase C.     

Enhancement of phage-mediated gene transfer by nuclear localization signal

The cell membrane and the nuclear membrane are two major barriers hindering the free movement of various macromolecules through animal cells. Nevertheless, some proteins can actively bypass these barriers by dint of intrinsic peptidic signals, so incorporation of these signals might improve the efficacy of artificial gene delivery vehicles. We examined the role of the nuclear localization signal (NLS) in gene transfer, using recombinant lambda phage as a model of the polymer/DNA complexes. We prepared a lambda phage displaying a 32-mer NLS of SV40 T antigen on its surface (NLS phage), and found that this NLS phage, delivered into the cytoplasm by appropriate devices, has higher affinity for the nucleus and induces the expression of encapsulated marker genes more efficiently than does the wild-type phage. This suggests that the 32-mer NLS peptide will become a practical tool for artificial gene delivery vehicles with enhanced nuclear targeting activity.     

A Quantitative Comparison of Human HT-1080 Fibrosarcoma Cells and Primary Human Dermal Fibroblasts Identifies a 3D Migration Mechanism with Properties Unique to the Transformed Phenotype

Here, we describe an engineering approach to quantitatively compare migration, morphologies, and adhesion for tumorigenic human fibrosarcoma cells (HT-1080s) and primary human dermal fibroblasts (hDFs) with the aim of identifying distinguishing properties of the transformed phenotype. Relative adhesiveness was quantified using self-assembled monolayer (SAM) arrays and proteolytic 3-dimensional (3D) migration was investigated using matrix metalloproteinase (MMP)-degradable poly(ethylene glycol) (PEG) hydrogels (“synthetic extracellular matrix” or “synthetic ECM”). In synthetic ECM, hDFs were characterized by vinculin-containing features on the tips of protrusions, multipolar morphologies, and organized actomyosin filaments. In contrast, HT-1080s were characterized by diffuse vinculin expression, pronounced β1-integrin on the tips of protrusions, a cortically-organized F-actin cytoskeleton, and quantitatively more rounded morphologies, decreased adhesiveness, and increased directional motility compared to hDFs. Further, HT-1080s were characterized by contractility-dependent motility, pronounced blebbing, and cortical contraction waves or constriction rings, while quantified 3D motility was similar in matrices with a wide range of biochemical and biophysical properties (including collagen) despite substantial morphological changes. While HT-1080s were distinct from hDFs for each of the 2D and 3D properties investigated, several features were similar to WM239a melanoma cells, including rounded, proteolytic migration modes, cortical F-actin organization, and prominent uropod-like structures enriched with β1-integrin, F-actin, and melanoma cell adhesion molecule (MCAM/CD146/MUC18). Importantly, many of the features observed for HT-1080s were analogous to cellular changes induced by transformation, including cell rounding, a disorganized F-actin cytoskeleton, altered organization of focal adhesion proteins, and a weakly adherent phenotype. Based on our results, we propose that HT-1080s migrate in synthetic ECM with functional properties that are a direct consequence of their transformed phenotype.