The Kinesin-4 Family
Claire T. Friel in The Kinesin Superfamily Handbook, 2020
Members of the Kinesin-4 family, which incorporates the previously identified Kinesin-10 family, have the ability to alter microtubule dynamics. The motor domain of members of the Kinesin-4 family is located N-terminally in the primary sequence and is immediately followed by a short neck-linker region. Members of the Kinesin-4 family display a range of modes of interaction with microtubules, although all members studied to date share the ability to alter microtubule dynamics. The mammalian Kinesin-4, KIF4, was originally discovered in the murine central nervous system and is strongly expressed in juvenile brain tissue. KIF4 appears to play similar roles in meiosis, localising to chromosomes throughout metaphase and transitioning to the midzone during anaphase. The mammalian Kinesin-4, KIF21B, plays a role in the regulation of both transport and microtubule dynamics in dendrites.
Mitosis
Dennis Bray in Cell Movements, 2000
This chapter is concerned with nuclear division of mitosis in a typical vertebrate cell. It shows that spindle microtubules, gaining access to the nuclear compartment, attach to chromosomal kinetochores. The chapter examines that in order to account for the erratic movements of chromosomes at metaphase, the kinetochore attachment must be of a special kind. During mitosis in plant and animal cells, populations of microtubules grow, attach to chromosomes, and maneuver them with amazing precision into two newly created nuclei. Mitosis itself is traditionally subdivided into a sequence of stages according to the behavior of the chromosomes, the principal stages being prophase, metaphase, anaphase , and telophase . Mitosis is not the only event in which chromosomes are moved within the cell. Sexual reproduction also requires extensive rearrangements of the genetic material under the guidance of microtubules.
Effects of External Agents and Monitering for Environmental Toxicants
Arun Kumar Sharma, Archana Sharma in Chromosome Techniques, 2020
The discovery of x-ray-induced mutation in Drosophila by Muller in 1927, followed by Stadler in Maize in 1928, provided the necessary impetus for research on the effects of outside agents on chromosomes. The most suitable chemical for the purpose of securing a large number of metaphase plates is colchicine as it causes metaphase arrest by inhibiting the operation of the spindle mechanism. The study of chromosome fragmentation by chemicals has a special significance in bringing out the differential nature of chromosome segments. The effects of different chemical agents and their modes of action have been dealt with in detail by several workers including our group. In the study of the effect of chemical agents on chromosomes, control experiment should be set up with water treatment alone in cases where water is used as the solvent of the chemical agent. The effects are modified by interactions between metals and the addition of external agents.
Unexpected repeat immature oocyte response after IVF stimulation: a case report
Published in Gynecological Endocrinology, 2018
Vandana Mishra, Lakshmi Chirumamilla
The purpose of ovarian stimulation in IVF is to recover mature oocytes at metaphase II stage which are capable of fertilization either when mixed with sperm or after ICSI. However, there have been instances when even after controlled ovarian stimulation (COS) and correct administration of human chorionic gonadotrophin (hCG) trigger for final oocyte maturation, the oocytes were found to be arrested at germinal vesicle (GV) or metaphase I (MI) stage. Similar dilemma is faced in cases of empty follicle syndrome (either genuine or due to inadequate response), however, in this condition, there is no retrieval of oocytes despite presence of mature looking follicles. We present an interesting case where despite presence of normally growing follicles and documentation of correct response to trigger and rise in estradiol levels, two subsequent IVF cycles; one triggered with recombinant hCG and second with GnRH agonist, hCG failed to yield mature oocytes. Both cycles yielded expected number of oocytes but all at immature MI stage even after dual trigger.
Double ovarian stimulation (DuoStim) protocol for fertility preservation in female oncology patients
Published in Human Fertility, 2017
Nikolaos Tsampras, Della Gould, Cheryl T. Fitzgerald
This article describes a revised ovarian stimulation protocol (DuoStim) for fertility preservation in female oncology patients which aims to maximise the number of gametes obtained with subsequent improvement in cumulative birth rate, without delaying cancer treatment. Ten patients diagnosed with malignancy between September 2014 and October 2015 were included. The patients were treated with the DuoStim protocol, undergoing two consecutive ovarian stimulation cycles and two oocyte retrievals. The primary outcome was the number of oocytes collected and vitrified during each oocyte retrieval and in total. The protocol was evaluated regarding medical risk and patients’ feedback. During the first oocyte collection 81 oocytes (61 metaphase II) were retrieved (mean = 8.1; range = 1–13) and during the second oocyte collection 82 oocytes (67 metaphase II) were retrieved (mean= 8.2; range = 1–19). A total of 163 oocytes (128 metaphase II) were collected (mean = 16.3; range = 6–32) and cancer treatment was not delayed for any of these patients. There were no cases of ovarian hyperstimulation syndrome recorded. More patients and long-term follow-up is needed to assess the efficacy and safety of the DuoStim protocol. However, these early results are encouraging, demonstrating an increase in number of mature oocytes retrieved during ovarian stimulation for oncology patients, without delaying cancer treatment.
Comparison of genetic changes between interphase and metaphase nuclei in monitoring CML and APL treatment using DC-FISH technique
Published in Cancer Biology & Therapy, 2004
Tahsin Yakut, Rıdvan Ali, Unal Egeli, Fahir Ozkalemkas, Ilker Ercan, Tülay Özçelik, Vildan Ozkocaman, Barboros Yigit, Ahmet Tunali
In leukemias, the monitoring techniques on the response after the treatment have clinical importance for evaluating new therapeutic approaches and identifying the risk of relapse. In this study, genetic changes before and after chemotherapy in interphase and metaphase nuclei of bone morrow of adults with provisional diagnosis of leukemia were compared to understand the molecular characterization and pathogenesis of the leukemia for the classification of diagnosis and prognosis. We examined bone morrow cells of 47 chronic myeloid leukemia (CML) cases (29 of 47 at the time of diagnosis, 31 of 47 after chemotherapy) with the bcr/abl translocation probes and of 10 acute promyelocytic leukemia (APL) cases (7 of 10 at the time of diagnosis, 4 of 10 after chemotherapy) with the PML/RAR_ translocation probes by using dual color-flourescence in situ hybridization (DC-FISH). For each case, 400 interphase nuclei and 11 to 25 metaphases nuclei were analysed. The ratios of translocations before and after chemotherapy were compared between interphase and metaphase nuclei. After chemotherapy, though, translocations were detected in interphase nuclei of 29 of the 31 CML and 4 of the 4 APL cases, these translocations were determined in metaphase nuclei of only 14 of the 31 CML and 1 of the 4 APL cases with very low ratios (p