Influence of native microbiota on survival of Ralstonia solanacearum phylotype II in river water microcosms

Ralstonia solanacearum phylotype II biovar 2 causes bacterial wilt in solanaceous hosts, producing severe economic losses worldwide. Waterways can be major dissemination routes of this pathogen, which is able to survive for long periods in sterilized water. However, little is known about its survival in natural water when other microorganisms, such as bacteriophages, other bacteria, and protozoa, are present. This study looks into the fate of a Spanish strain of R. solanacearum inoculated in water microcosms from a Spanish river, containing different microbiota fractions, at 24 degrees C and 14 degrees C, for a month. At both temperatures, R. solanacearum densities remained constant at the initial levels in control microcosms of sterile river water while, by contrast, declines in the populations of the introduced strain were observed in the nonsterile microcosms. These decreases were less marked at 14 degrees C. Lytic bacteriophages present in this river water were involved in the declines of the pathogen populations, but indigenous protozoa and bacteria also contributed to the reduced persistence in water. R. solanacearum variants displaying resistance to phage infection were observed, but only in microcosms without protozoa and native bacteria. In water microcosms, the temperature of 14 degrees C was more favorable for the survival of this pathogen than 24 degrees C, since biotic interactions were slower at the lower temperature. Similar trends were observed in microcosms inoculated with a Dutch strain. This is the first study demonstrating the influence of different fractions of water microorganisms on the survival of R. solanacearum phylotype II released into river water microcosms.     

The flexibility of actin filaments as revealed by fluorescence resonance energy transfer. The influence of divalent cations

The temperature profile of the fluorescence resonance energy transfer efficiency normalized by the fluorescence quantum yield of the donor in the presence of acceptor, f', was measured in a way allowing the independent investigation of (i) the strength of interaction between the adjacent protomers (intermonomer flexibility) and (ii) the flexibility of the protein matrix within actin protomers (intramonomer flexibility). In both cases the relative increase as a function of temperature in f' is larger in calcium-F-actin than in magnesium-F-actin in the range of 5-40 degrees C, which indicates that both the intramonomer and the intermonomer flexibility of the actin filaments are larger in calcium-F-actin than those in magnesium-F-actin. The intermonomer flexibility was proved to be larger than the intramonomer one in both the calcium-F-actin and the magnesium-F-actin. The distance between Gln41 and Cys374 residues was found to be cation-independent and did not change during polymerization at 21 degrees C. The steady-state fluorescence anisotropy data of fluorophores attached to the Gln41 or Cys374 residues suggest that the microenvironments around these regions are more rigid in the magnesium-loaded actin filament than in the calcium-loaded form.     

Single step recombinant human growth hormone (rhGH) purification from milk by peptide affinity chromatography

Recombinant human growth hormone (rhGH) is used for the treatment of several pathologies, most of them related to growth. Although different expression systems can be used for its production, the milk from transgenic cows is one of the most interesting due to the high rhGH level achieved (5 g/L). We have designed and synthesized short peptides (9 or 10 amino acid long) using Fmoc chemistry and studied their ability to purify rhGH from milk once immobilized on an agarose support. Using spiked milk with the hormone as a sample, rhGH was purified with 88% yield and 92% purity in a single step with a fold purification of 4.5. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:999–1005, 2018     

Diagnosis of invasive fungal disease in hospitalized patients with chronic obstructive pulmonary disease

Background

The role of culture-independent techniques (galactomannan, (1-3)-β-d-glucan) in the early diagnosis of invasive fungal diseases (IFD) is well assessed in hematological patients, but there are no clear conclusions in patients with chronic obstructive pulmonary disease (COPD).

Mouse SLLP1, a sperm lysozyme-like protein involved in sperm-egg binding and fertilization

This study demonstrates the retention of mouse sperm lysozyme-like protein (mSLLP1) in the equatorial segment of spermatozoa following the acrosome reaction and a role for mSLLP1 in sperm-egg binding and fertilization. Treatment of cumulus intact oocytes with either recmSLLP1 or its antiserum resulted in a significant (P < or = 0.05) inhibition of fertilization. Co-incubation of zona-free mouse oocytes with capacitated mouse spermatozoa in the presence of varying concentrations of anti-recmSLLP1 serum or recmSLLP1 also inhibited sperm-oolemma binding. A complete inhibition of binding and fusion of spermatozoa to the oocyte occurred at 12.5 muM concentration of recmSLLP1, while conventional chicken and human lysozymes did not block sperm-egg binding. mSLLP1 showed receptor sites in the perivitelline space as well as on the microvillar region of the egg plasma membrane. The retention of mSLLP1 in the equatorial segment of acrosome-reacted sperm, the inhibitory effects of both recmSLLP1 and antibodies to SLLP1 on in vitro fertilization with both cumulus intact and zona-free eggs, and the definition of complementary SLLP1-binding sites on the egg plasma membrane together support the hypothesis that a c lysozyme-like protein is involved in the binding of spermatozoa to the egg plasma membrane during fertilization.     

Low concentration structural dynamics of lanreotide and somatostatin‐14

Lanreotide, a synthetic cyclic octapeptide, analogue of the peptide hormone somatostatin‐14 (SST‐14), is routinely used as a long‐acting medication in the management of neuroendocrine tumors. Despite its therapeutic importance, low concentration structural data is still lacking for lanreotide. In fact, the major part of the previous structural investigations were focused on the remarkable aggregation properties of this peptide, appearing at high concentrations (>5 mM). Here, we have applied three optical spectroscopic techniques, i.e. fluorescence, circular dichroism and Raman scattering, for analyzing the structural dynamics at the concentrations below 5 mM, where lanreotide exists either in a monomer state or at the first stages of aggregation. The obtained data from lanreotide were discussed through their comparison with those collected from SST‐14, leading us to the following conclusions: (i) The central D‐Trp residue, forming with its adjacent Lys the main receptor interacting part of lanreotide, keeps a constant high rotational freedom whatever the environment (water, water/methanol, methanol). (ii) A solvent‐dependent tight β‐turn, belonging to the type‐II' family, is revealed in lanreotide. (iii) Raman data analyzed by band decomposition in the amide (I and III) regions allowed estimation of different secondary structural elements within the millimolar range. Interestingly, the applied protocol shows a perfect agreement between the structural features provided by the amide I and amide III Raman markers. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1019–1028, 2014.     

CDK-dependent phosphorylation of Mob2 is essential for hyphal development in Candida albicans

Nuclear Dbf2-related (NDR) protein kinases are essential components of regulatory pathways involved in cell morphogenesis, cell cycle control, and viability in eukaryotic cells. For their activity and function, these kinases require interaction with Mob proteins. However, little is known about how the Mob proteins are regulated. In Candida albicans, the cyclin-dependent kinase (CDK) Cdc28 and the NDR kinase Cbk1 are required for hyphal growth. Here we demonstrate that Mob2, the Cbk1 activator, undergoes a Cdc28-dependent differential phosphorylation on hyphal induction. Mutations in the four CDK consensus sites in Mob2 to Ala significantly impaired hyphal development. The mutant cells produced short hyphae with enlarged tips that displayed an illicit activation of cell separation. We also show that Cdc28 phosphorylation of Mob2 is essential for the maintenance of polarisome components at hyphal tips but not at bud tips during yeast growth. Thus we have found a novel signaling pathway by which Cdc28 controls Cbk1 through the regulatory phosphorylation of Mob2, which is crucial for normal hyphal development.     

Climate,landscape, habitat,and woodland management associations with hazel dormouse Muscardinus avellanarius population status

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