Acetylation of SUMO1 Alters Interactions with the SIMs of PML and Daxx in a Protein-Specific Manner

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Drosophila female germline stem cells undergo mitosis without nuclear breakdown

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Solution Structure of the HIV-1 Intron Splicing Silencer and Its Interactions with the UP1 Domain of Heterogeneous Nuclear Ribonucleoprotein (hnRNP) A1

Splicing patterns in human immunodeficiency virus type 1 (HIV-1) are maintained through cis regulatory elements that recruit antagonistic host RNA-binding proteins. The activity of the 3′ acceptor site A7 is tightly regulated through a complex network of an intronic splicing silencer (ISS), a bipartite exonic splicing silencer (ESS3a/b), and an exonic splicing enhancer (ESE3). Because HIV-1 splicing depends on protein-RNA interactions, it is important to know the tertiary structures surrounding the splice sites. Herein, we present the NMR solution structure of the phylogenetically conserved ISS stem loop. ISS adopts a stable structure consisting of conserved UG wobble pairs, a folded 2X2 (GU/UA) internal loop, a UU bulge, and a flexible AGUGA apical loop. Calorimetric and biochemical titrations indicate that the UP1 domain of heterogeneous nuclear ribonucleoprotein A1 binds the ISS apical loop site-specifically and with nanomolar affinity. Collectively, this work provides additional insights into how HIV-1 uses a conserved RNA structure to commandeer a host RNA-binding protein.     

Techniques for the detection of pathogenic Cryptococcus species in wood decay substrata and the evaluation of viability in stored samples

In this study, we evaluated several techniques for the detection of the yeast form of Cryptococcus in decaying wood and measured the viability of these fungi in environmental samples stored in the laboratory. Samples were collected from a tree known to be positive for Cryptococcus and were each inoculated on 10 Niger seed agar (NSA) plates. The conventional technique (CT) yielded a greater number of positive samples and indicated a higher fungal density [in colony forming units per gram of wood (CFU.g^-1) ] compared to the humid swab technique (ST). However, the difference in positive and false negative results between the CT-ST was not significant. The threshold of detection for the CT was 0.05.10³ CFU.g^-1, while the threshold for the ST was greater than 0.1.10³ CFU^-1. No colonies were recovered using the dry swab technique. We also determined the viability of Cryptococcus in wood samples stored for 45 days at 25ºC using the CT and ST and found that samples not only continued to yield a positive response, but also exhibited an increase in CFU.g^-1, suggesting that Cryptococcus is able to grow in stored environmental samples. The ST.1, in which samples collected with swabs were immediately plated on NSA medium, was more efficient and less laborious than either the CT or ST and required approximately 10 min to perform; however, additional studies are needed to validate this technique.     

The goatfish Pseudupeneus maculatus and its follower fishes at an oceanic island in the tropical west Atlantic

The influence of a substratum-disturbing forager, the spotted goatfish Pseudupeneus maculatus on the assemblage of its escorting, opportunistic-feeding fishes was examined at Fernando de Noronha Archipelago (tropical west Atlantic). Followers attracted to spotted goatfish foraging singly differed from followers of spotted goatfish foraging in groups in several characteristics. The larger the nuclear fish group, the greater the species richness and number of individuals of followers. Moreover, groups of foraging spotted goatfish attracted herbivores, not recorded for spotted goatfish foraging singly. The size of follower individuals increased with the size and the number of foraging spotted goatfish. The zoobenthivorous habits of the spotted goatfish and its ability to disturb a variety of soft substrata render it an important nuclear fish for several follower species of the reef fish assemblage at Fernando de Noronha.     

Do borderline nuclear changes in gynaecological cytlogy constitute a reliable reporting category?

Fourteen laboratories participated in a national slide exchange study to investigate whether borderline nuclear changes (BNC) constitute a reliable reporting category. Slides were submitted by participating laboratories, having achieved a 100% intralaboratory consensus at the primary screener, checker, and medical levels. Sets of seven slides were examined in laboratories for 1 week, and exchanges were undertaken over a 6-month period. Each laboratory was requested to submit three consensus opinions on each slide at the primary screener, checker, and medical levels.
Response patterns for submitted slides achieving a reporting category consensus at the 50 and 80% consensus levels indicated that negative, BNC, and mild dyskaryosis are distinct and comparable categories. Similarly, the two subcategories of BNC with or without human papillomavirus (HPV) are nearly as distinct as the overall BNC category.
The percentage of submitted slides achieving consensus at consensus levels between 50 and 80% produced variable findings with regard to the practical success of the main reporting categories. The negative category was reasonably successful, whereas mild dyskaryosis was consistently poor. Borderline nuclear changes were successful at the 50% consensus level but showed a rapid decline by the 65% consensus level. The reason(s) for this remains speculative but indicates a possible potential of BNC to work successfully with additional training and education.
Reporting practices were not consistent among the laboratories and differences were identified between medical and nonmedical staff. A high use of the BNC category was noted in slides that failed to achieve consensus. A national study assessing all grades of abnormalities would appear essential.     

Mercury in blood cells—Altered elemental profiles

The study was composed of 27 persons that displayed vague symptoms similar to those of the victims of Minamata and Iraq. Skew distributions of mercury were observed in individual erythrocytes and neutrophil granulocytes when measured by PIXE. Mercury could not be detected in the platelets. The erythrocytes also displayed lowered concentrations of magnesium and zinc, together with increased concentrations of calcium and strontium. The neutrophils displayed decreased concentrations of magnesium and zinc and increased concentrations of calcium, strontium, and iron. The presence of mercury and the altered elemental profiles in the erythrocytes and the neutrophil granulocytes are suggested as early signs of exposure.     

Role of nuclear analytical probe techniques in biological trace-element research

Many biomedical experiments require the qualitative and quantitative localization of trace elements with high sensitivity and good spatial resolution. The feasibility of measuring the chemical form of the elements, the time course of trace element metabolism, and conducting experiments in living biological systems are also important requirements for biological trace element research. Nuclear analytical techniques that employ ion or photon beams have grown in importance in the past decade and have led to several new experimental approaches. Some of the important features of these methods are reviewed here along with their role in trace element research. Examples of their use are given to illustrate potential for new research directions. It is emphasized that the effective application of these methods necessitates a closely integrated multidisciplinary scientific team.     

Detection and characterization of acidic compartments (vacuoles) in Chlorella vulgaris 11h cells by 31P-in vivo NMR spectroscopy and cytochemical techniques

Acidic inorganic phosphate (Pi) pool (pH around 6) was detected besides the cytoplasmic pool in intact cells of Chlorella vulgaris 11h by ³¹P-in vivo nuclear magnetic resonance (NMR) spectroscopy. It was characterized as acidic compartments (vacuoles) in combination with the cytochemical technique; staining the cells with neutral red and chloroquine which are known as basic reagents specifically accumulated in acidic compartments. Under various conditions, the results obtained with the cytochemical methods were well correlated with those obtained from in vivo NMR spectra; the vacuoles were well developed in the cells at the stationary growth phase where the acidic Pi signal was detected. In contrast, cells at the logarithmic phase in which no acidic Pi signal was detected contained only smaller vesicles that accumulated these basic reagents. No acidic compartment was detected by both cytochemical technique and ³¹P-NMR spectroscopy when the cells were treated with NH₄OH. The vacuolar pH was lowered by the anaerobic treatment of the cells in the presence of glucose, while it was not affected by the external pH during the preincubation ranging from 3 to 10. Possible vacuolar functions in unicellular algae especially with respect to intracellular pH regulation are discussed.Non-standard abbreviations EDTA ethylenediaminetetraacetic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - MDP methylene diphosphonic acid - NMR nuelear magnetic resonance - PCA perchloric acid - PCV packed cell volume - Pi inorganic phosphate - Pic sytoplasmic inorganic phosphate - Piv vacuolar inorganic phosphate - ppm parts per million - SP sugar phosphates - TCA trichloroacetic acid