Pleomorphism and Viability of the Lyme Disease Pathogen Borrelia burgdorferi Exposed to Physiological Stress Conditions: A Correlative Cryo-Fluorescence and Cryo-Scanning Electron Microscopy Study.

To understand the response of the Lyme disease spirochete Borrelia burgdorferi exposed to stress conditions and assess the viability of this spirochete, we used a correlative cryo-fluorescence and cryo-scanning microscopy approach. This approach enables simple exposition of bacteria to various experimental conditions that can be stopped at certain time intervals by cryo-immobilization, examination of cell viability without necessity to maintain suitable culture conditions during viability assays, and visualization of structures in their native state at high magnification. We focused on rare and transient events e.g., the formation of round bodies and the presence of membranous blebs in spirochetes exposed to culture medium, host sera either without or with the bacteriolytic effect and water. We described all crucial steps of the workflow, particularly the influence of freeze-etching and accelerating voltage on the visualization of topography. With the help of newly designed cryo-transport device, we achieved greater reproducibility.

Provision and quality assurance of preimplantation genetic diagnosis in Europe.

Preimplantation genetic diagnosis (PGD) is now well established and provided in many European countries. However, regulations, professional standards and accreditation requirements can differ notably. Furthermore, no comprehensive independent data exist either about practice and provision in Europe or about the quality assurance practices and procedures designed to optimize the quality of the results. Consequently, a study was launched to obtain knowledge, currently lacking, of the provision and quality assurance of PGD services and cross-border activities in Europe. An online questionnaire was developed and sent to PGD providers, and expert opinions were obtained through interviews with professionals in specific countries. Information was gathered from 53 centres offering PGD in 17 European countries. There is a diverse array of tests available, with a trend for custom-made services. Although half of the centres have a designated quality manager, just 33% have achieved or are preparing for accreditation or certification. About 66% of the centres responded that they did not participate in external quality assessment, a problem exacerbated by the lack of existing PGD-specific schemes. Approximately 19% of the centres do not keep data on accuracy and 9% do not even follow up until birth. PGD is an expanding activity with an increasing international flow that accounts for approximately one-third of the activity reported. The survey highlights a significant need for improvement in quality assurance in PGD centres. On the positive side, important improvements in the quality management of these services are expected with the European Tissue Directive entering into force.

The bidirectional phase-shifting effects of melatonin on the arginine vasopressin secretion rhythm in rat suprachiasmatic nuclei in vitro.

In vivo melatonin serves as a feedback signal to the circadian pacemaker located in the suprachiasmatic nuclei (SCN) and in vitro it phase advances the circadian rhythm of electrical activity in pacemaker cells. However, the occurrence and nature of phase shifting in secretion by cultured SCN neurons has not yet been established. Here we studied the effects of melatonin on the pattern of spontaneous arginine vasopressin (AVP) release in organotypic SCN slices. This culture mimicked the in vivo circadian AVP secretory rhythm, with low release during the subjective night and with peaks in secretion during the middle of subjective day. The endogenous period of the AVP secretory rhythm in organotypic culture ranged between 23 and 26 h, with the mean period of 24.1 +/- 0.3 h. Melatonin (10 nM) had variable effects on the pattern of AVP secretion depending on time of its application directly to the medium with organotypic SCN slices. When introduced at circadian time 22, 2 and 6 (the times corresponding to the late night and early day), melatonin delayed the AVP secretory rhythm by 1-4 h. When applied at circadian time 10 (late day), however, melatonin advanced the AVP secretory rhythm by about 2 h. At other circadian times, melatonin was ineffective. These results indicate that melatonin exhibits the bidirectional phase-shifting effects on circadian secretory rhythm clock, which depends on the time-window of its application.