DNA-binding polarity of human replication protein A positions nucleases in nucleotide excision repair

The human single-stranded DNA-binding replication A protein (RPA) is involved in various DNA-processing events. By comparing the affinity of hRPA for artificial DNA hairpin structures with 3′- or 5′-protruding single-stranded arms, we found that hRPA binds ssDNA with a defined polarity; a strong ssDNA interaction domain of hRPA is positioned at the 5′ side of its binding region, a weak ssDNA-binding domain resides at the 3′ side. Polarity appears crucial for positioning of the excision repair nucleases XPG and ERCC1–XPF on the DNA. With the 3′-oriented side of hRPA facing a duplex ssDNA junction, hRPA interacts with and stimulates ERCC1–XPF, whereas the 5′-oriented side of hRPA at a DNA junction allows stable binding of XPG to hRPA. Our data pinpoint hRPA to the undamaged strand during nucleotide excision repair. Polarity of hRPA on ssDNA is likely to contribute to the directionality of other hRPA-dependent processes as well.     

Retroposed new genes out of the X in Drosophila

New genes that originated by various molecular mechanisms are an essential component in understanding the evolution of genetic systems. We investigated the pattern of origin of the genes created by retroposition in Drosophila. We surveyed the whole Drosophila melanogaster genome for such new retrogenes and experimentally analyzed their functionality and evolutionary process. These retrogenes, functional as revealed by the analysis of expression, substitution, and population genetics, show a surprisingly asymmetric pattern in their origin. There is a significant excess of retrogenes that originate from the X chromosome and retropose to autosomes; new genes retroposed from autosomes are scarce. Further, we found that most of these X-derived autosomal retrogenes had evolved a testis expression pattern. These observations may be explained by natural selection favoring those new retrogenes that moved to autosomes and avoided the spermatogenesis X inactivation, and suggest the important role of genome position for the origin of new genes.     

Effects of air pollution on cup a 3 allergen in Cupressus arizonica pollen grains.

BACKGROUND: Cupressaceae is a family of plants resistant to airborne contamination, and its pollen is the main cause of winter allergic respiratory diseases, especially in North America, Japan, and Mediterranean countries. Recently, a major allergen from Cupressus arizonica pollen grains, Cup a 3, was cloned and expressed. OBJECTIVE: To study the effects of air pollution on the expression of Cup a 3, a thaumatinlike protein, in C. arizonica pollen grains using a combination of transmission electron microscopy and immunocytochemical techniques. METHODS: Observations were made in mature and hydrated C. arizonica pollen grains from various regions in Spain with different degrees of air pollution. Specimens were fixed using freezing protocols, and ultrathin sections were incubated with anti-rCup a 3 rabbit polyclonal antibodies. RESULTS: Labeling of Cup a 3 was detected in mature and hydrated C. arizonica pollen grains. It was more intense in pollen from polluted air regions, and abundant gold particles were observed as they were released through the pollen grain walls. Furthermore, gold particles remained abundant in the pollen cytoplasm. The labeling was noticeably lower in pollen grains from unpolluted air regions. CONCLUSIONS: Cup a 3 is present in the cytoplasm and walls of cypress pollen grains during the air dispersion and hydration stages. The abundance of Cup a 3 in pollen grains under polluted air conditions indicates that these cypresses intensify their activity as a defense from environmental pollution, thus strengthening their allergenicity.     

Automated identification of gram-positive bacteria.

A total of 451 strains of gram-positive bacteria were identified with a prototype of the Gram-Positive Identification card used in conjunction with the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Of the species that the Gram-Positive Identification card is capable of identifying, 85% of staphylococcal, 50% of beta-hemolytic group A, B, C, F, and G streptococcal, 91% of group D streptococcal, 100% of pneumococcal, 63% of viridans streptococcal, and 100% of Listeria monocytogenes strains tested displayed Gram-Positive Identification card identifications that were in agreement with identifications obtained by conventional methods.     

Characterization of FMR1 proteins isolated from different tissues

FMR1 protein expression was studied in different tissues. Inhuman, monkey and murine tissues, high molecular mass FMR1 proteins(67–80 kDa) are found, as shown in lymphobiastoid celiiines. The identity of these proteins was confirmed by theirabsence in tissues from patients with the fragile X syndromeand a FMR1 knock-out mouse. An IIe367Asn substitution in theFMR1 protein did not aiter the transiation, processing and localizationof FMR1 proteins in lymphoblastoid cells from a patient carryingthis mutation. All the high molecular mass FMR1 proteins isolatedfrom normal lymphoblastoid cells and cells from the patientwith the IIe367Asn substitution were able to bind RNA. However,the FMR1 proteins of the patient had reduced affinity for RNAbinding at high salt concentrations. In some human, monkey andmurine tissues low molecular mass FMR1 proteins (39–41kDa) were found, which had the same N terminus as the 67–90kDa isoforms, but differ in their C terminus and are thereforemost likely the result of carboxy-terminal proteolytic cleavage.These low molecular mass FMR1 proteins did not bind RNA, incontrast with the high molecular mass FMR1 proteins. The significanceof these low molecular mass proteins remains to be studied.     

Influence of resistance to antidepressant pharmacotherapy on short-term response to electroconvulsive therapy

BACKGROUND: Few studies assessing the influence of resistance to antidepressant pharmacotherapy on the response to subsequent electroconvulsive therapy (ECT) are found in the literature. Results are somewhat conflicting and may not be applicable to the population of depressed patients in The Netherlands. The aim of this study is to assess the influence of medication resistance on the short-term response to ECT in a population of severely depressed inpatients in The Netherlands, where ECT is an exceptional treatment, often used as a final treatment option. METHODS: We reviewed the records of 41 consecutive inpatients with major depression according to DSM-III-R criteria and rated each patients' antidepressant pharmacotherapy prior to ECT. We examined the extent to which medication resistance was related to short-term response to ECT. RESULTS: When a reduction of at least 50% on the Hamilton Rating Scale for Depression (HRSD) post-ECT compared to pre-ECT (partial remission) is used as response criterion, medication resistant patients and patients without established medication resistance were equally likely to respond to subsequent ECT. When a post-ECT HRSD score < or = 7 (full remission) is used as response criterion, medication resistant patients were less likely to respond to subsequent ECT (8/29=27.6%) than patients who did not receive adequate antidepressant pharmacotherapy prior to ECT (6/12=50.0%), although the difference in response rate was not statistically significant. LIMITATIONS: This study has a retrospective nature and a relatively small sample size. CONCLUSION: Antidepressant medication resistance does not seem to have an influence on the short-term response to subsequent ECT. However, when the number of patients achieving full remission is concerned, a substantial percentage of antidepressant medication resistant patients respond to ECT, although their response rate was nearly half compared to that of patients without prior adequate treatment with antidepressants. This difference in response rate was not statistically significant. ECT seems to be an effective treatment for both patients with and without prior adequate treatment with antidepressants in this Dutch population.     

Sonic hedgehog guides commissural axons along the longitudinal axis of the spinal cord

Dorsal commissural axons in the developing spinal cord cross the floor plate, then turn rostrally and grow along the longitudinal axis, close to the floor plate. We used a subtractive hybridization approach to identify guidance cues responsible for the rostral turn in chicken embryos. One of the candidates was the morphogen Sonic hedgehog (Shh). Silencing of the gene SHH (which encodes Shh) by in ovo RNAi during commissural axon navigation demonstrated a repulsive role in post-commissural axon guidance. This effect of Shh was not mediated by Patched (Ptc) and Smoothened (Smo), the receptors that mediate effects of Shh in morphogenesis and commissural axon growth toward the floor plate. Rather, functional in vivo studies showed that the repulsive effect of Shh on postcommissural axons was mediated by Hedgehog interacting protein (Hip).