Development of a miniaturized assay for the high-throughput screening program for poly(ADP-ribose) polymerase-1

Poly(ADP-ribose) polymerase (PARP) plays a pivotal role in the repair of DNA strand breaks. However, excessive activation of PARP causes a rapid depletion of intracellular energy, leading to cell death. PARP inhibitors may have potential therapeutic benefit in the treatment of myocardial ischemia, stroke, and neurodegenerative disease. With these emerging medicinal interests, various screening programs have identified small molecules that inhibit PARP with reasonable potencies. However, the increasing numbers of diverse small molecules generated through combinatorial chemistry necessitate the use of robust assays with good sensitivity and specificity for use as a high-throughput screening (HTS) program. Here, we report the development and the validation of a nonisotopic PARP-1 assay suitable for HTS by converting a biotinylated NAD-based colorimetric assay to a miniaturized 384-well plate format. Comparing with the conventional methods, this miniaturized PARP-1 inhibition assay was equally sensitive with excellent reproducibility and cost-effectiveness. Because nonisotopic PARP-1 inhibition assays are widely used, the methodology described in this article can expand the feasibility of this assay as a high-throughput assay for screening of PARP-1 inhibitors from a random chemical library.

Technical Note: Improved Extraction Method with Hexane for Gas Chromatographic Analysis of Conjugated Linoleic Acids

Extraction properties of different solvents (chloroform/methanol, hexane/isopropanol, and hexane) were studied for the gas chromatographic analysis of conjugated linoleic acids (CLA) from probiotic bacteria grown in de Man, Rogosa, and Sharpe medium. As compared with chloroform/methanol and hexane/isopropanol, hexane showed comparable extraction efficiency for CLA from unspent de Man, Rogosa, and Sharpe medium, but showed minimal extraction of oleic acid originated from the emulsifier in broth. The extraction efficiency of CLA by hexane was influenced by the broth pH, showing the optimal pH of 7.0. Repeated extraction with hexane increased the yield. Extraction with hexane showed excellent recovery of spiked CLA from the spent broth with up to 97.2% (standard deviation of 1.74%). This represents the highest recovery of CLA from culture broth ever reported. The sample size was also successfully reduced to 0.5 mL to analyze CLA from the broth without impairment of analytical data. This smaller sample size in the 1.5-mL microcentrifuge tube using a small bench-top centrifuge reduced analytical time significantly.

The core centromere and Sgo1 establish a 50-kb cohesin-protected domain around centromeres during meiosis I

The stepwise loss of cohesins, the complexes that hold sister chromatids together, is required for faithful meiotic chromosome segregation. Cohesins are removed from chromosome arms during meiosis I but are maintained around centromeres until meiosis II. Here we show that Sgo1, a protein required for protecting centromeric cohesins from removal during meiosis I, localizes to cohesin-associated regions (CARs) at the centromere and the 50-kb region surrounding it. Establishment of this Sgo1-binding domain requires the 120-base-pair (bp) core centromere, the kinetochore component Bub1, and the meiosis-specific factor Spo13. Interestingly, cohesins and the kinetochore proteins Iml3 and Chl4 are necessary for Sgo1 to associate with pericentric regions but less so for Sgo1 to associate with the core centromeric regions. Finally, we show that the 50-kb Sgo1-binding domain is the chromosomal region where cohesins are protected from removal during meiosis I. Our results identify the portions of chromosomes where cohesins are protected from removal during meiosis I and show that kinetochore components and cohesins themselves are required to establish this cohesin protective domain.

Enzymatic ability of Bifidobacterium animalis subsp. lactis to hydrolyze milk proteins: identification and characterization of endopeptidase O

The proteolytic system of Bifidobacterium animalis subsp. lactis was analyzed, and an intracellular endopeptidase (PepO) was identified and characterized. This work reports the first complete cloning, purification, and characterization of a proteolytic enzyme in Bifidobacterium spp. Aminopeptidase activities (general aminopeptidases, proline iminopeptidase, X-prolyl dipeptidylaminopeptidase) found in cell extracts of B. animalis subsp. lactis were higher for cells that had been grown in a milk-based medium than for those grown in MRS. A high specific proline iminopeptidase activity was observed in B. animalis subsp. lactis. Whole cells and cell wall-bound protein fractions showed no caseinolytic activity; however, the combined action of intracellular proteolytic enzymes could hydrolyze casein fractions rapidly. The endopeptidase activity of B. animalis subsp. lactis was examined in more detail, and the gene encoding an endopeptidase O in B. animalis subsp. lactis was cloned and overexpressed in Escherichia coli. The deduced amino acid sequence for B. animalis subsp. lactis PepO indicated that it is a member of the M13 peptidase family of zinc metallopeptidases and displays 67.4% sequence homology with the predicted PepO protein from Bifidobacterium longum. The recombinant enzyme was shown to be a 74-kDa monomer. Activity of B. animalis subsp. lactis PepO was found with oligopeptide substrates of at least 5 amino acid residues, such as met-enkephalin, and with larger substrates, such as the 23-amino-acid peptide alpha s1-casein(f1-23). The predominant peptide bond cleaved by B. animalis subsp. lactis PepO was on the N-terminal side of phenylalanine residues. The enzyme also showed a post-proline secondary cleavage site.

Tacrolimus decreases the expression of eotaxin, CCR3, RANTES and interleukin-5 in atopic dermatitis

BACKGROUND

There is a lack of studies on the effect of tacrolimus on eosinophils and related molecules including eotaxin, CCR3, RANTES and interleukin (IL)-5.

OBJECTIVES

To investigate the effects of tacrolimus on in vivo eosinophil counts and on the related molecules eotaxin, CCR3, RANTES and IL-5 in patients with atopic dermatitis (AD).

METHODS

Lesional skin specimens and sera were obtained from 15 patients with AD and from 15 normal controls. For 8 weeks, the patients with AD applied 0.03% tacrolimus ointment to all affected areas twice daily. Blood sampling and skin biopsies were then repeated. We evaluated serum eotaxin and IL-5 levels, and tissue eotaxin, CCR3, RANTES and IL-5 levels. Additionally, tissue levels of eotaxin and CCR3 mRNA were measured.

RESULTS

After treatment with topical tacrolimus twice daily for 8 weeks, significant decreases were found in serum IL-5 levels, immunoreactive cell counts of eotaxin, IL-5, CCR3 and RANTES in AD skin, and tissue eosinophil counts. However, the change in the serum eosinophil count was not statistically significant, and mRNA levels of eotaxin and CCR3 were not decreased significantly after treatment.

CONCLUSIONS

Topical tacrolimus reduces the number of eosinophils in tissue and suppresses the expression of eotaxin, CCR3, RANTES and IL-5 related to proliferation, recruitment, activation and survival of eosinophils.

Spo13 maintains centromeric cohesion and kinetochore coorientation during meiosis I

BACKGROUND

The meiotic cell cycle, the cell division cycle that leads to the generation of gametes, is unique in that a single DNA replication phase is followed by two chromosome segregation phases. During meiosis I, homologous chromosomes are segregated, and during meiosis II, as in mitosis, sister chromatids are partitioned. For homolog segregation to occur during meiosis I, physical linkages called chiasmata need to form between homologs, sister chromatid cohesion has to be lost in a stepwise manner, and sister kinetochores must attach to microtubules emanating from the same spindle pole (coorientation).

RESULTS

Here we show that the meiosis-specific factor Spo13 functions in two key aspects of meiotic chromosome segregation. In cells lacking SPO13, cohesin, which is the protein complex that holds sister chromatids together, is not protected from removal around kinetochores during meiosis I but is instead lost along the entire length of the chromosomes. We furthermore find that Spo13 promotes sister kinetochore coorientation by maintaining the monopolin complex at kinetochores. In the absence of SPO13, Mam1 and Lrs4 disassociate from kinetochores prematurely during pro-metaphase I and metaphase I, resulting in a partial defect in sister kinetochore coorientation in spo13 Delta cells.

CONCLUSIONS

Our results indicate that Spo13 has the ability to regulate both the stepwise loss of sister chromatid cohesion and kinetochore coorientation, two essential features of meiotic chromosome segregation.

Treatment of spontaneous arterial dissections with stent placement for preservation of the parent artery

BACKGROUND

A wide variety of treatment regimens have been advocated for dissections involving the intracranial arteries. Recently, the stent can be used to exclude the aneurysm from the circulation and preserve the parent artery. We evaluated the safety and efficacy of stent angioplasty for intracranial arterial dissections.

METHODS

Ten patients with spontaneous dissections, nine vertebral artery and one internal carotid artery lesions underwent endovascular treatment using stent placement as primary treatment modality. One stent placement was attempted in five patients initially. Three patients were intentionally treated with two overlapping stents which completely covered the aneurysm orifice. Two tandem stents were used in one patient to allow spanning the entire length of the dissection. Stent-assisted coil embolization was performed in one patient.

RESULTS

Of the 10 patients in whom stenting was tried, the overall success in reaching the target lesion with stents was 90%. Of the 9 patients treated with stents, stent release and positioning were considered optimal in 7 patients (77.8%) and suboptimal in two. Lesions of 8 patients were improved or stable in angiographic follow-up. However, one pseudo-aneurysm was enlarged, and subsequently, was treated by proximal occlusion using coils. There were no instances of postprocedural ischaemic attacks, new neurological deficits, and no new minor or major strokes prior to patient discharge. All parent arteries of the patient who underwent the successful procedure were preserved. On the modified Rankin scale used for the follow up, all patients were assessed as functionally improved or of stable clinical status.

CONCLUSIONS

The success in reducing dissection-induced stenosis or pseudo-aneurysm, the patency rate obtained at follow-up, and the lack of strokes (ischaemic or haemorrhagic) suggest that stent placement offers a viable alternative to complex surgical procedures or deconstructive procedures. The long-term efficacy and durability of stent placement for arterial dissection remains to be determined in a large series.

Tacrolimus reduces staphylococcal colonization on the skin in Korean atopic dermatitis patients

It is well known that topical tacrolimus is safe and effective in the treatment of atopic dermatitis (AD) patients. Tacrolimus is primarily an immunosuppressive agent without any antistaphylococcal effects. Thus colonization of Staphylococcus aureus on the skin of patients treated with this agent might be increased. The purpose of this study was to determine the effect of tacrolimus on S. aureus colonization in patients with AD and to compare the results with clinical severity and skin barrier function. We enrolled 65 patients with moderate to severe AD. They were treated with 0.03% tacrolimus ointment twice daily for 4 weeks. Clinical severity was assessed by the eczema area and severity index (EASI). S. aureus colonization was measured by the tape method. Skin barrier function was checked by measuring transepidermal water loss (TEWL). Evaluations were performed at weeks 0 (baseline), 1, 2 and 4. The results were compared and statistical analysis was performed. S. aureus colonization was significantly decreased with tacrolimus treatment at week 1 compared with baseline. However, there were no differences among weeks 1, 2 and 4. EASI and TEWL showed a decreasing tendency in a time-dependent fashion. The correlations between data were variable.

Purification and Characterization of Intracellular Proteinase from Lactobacillus casei ssp. casei LLG

The intracellular proteinase of Lactobacillus casei ssp. casei LLG was isolated in the cytoplasmic fraction with 0.05 M Tris-HCl buffer (pH 7.5). The enzyme was purified by the fast protein liquid chromatography system equipped with ion-exchange and gel filtration chromatographies. This proteinase comprised a single monomeric form and had a molecular weight of about 55 kDa and an isoelectric point near pH 4.9. The optimum pH and temperature for the enzyme activity were determined to be pH 6.5 and 37 degrees C, respectively. The enzyme was inactivated by metal-chelating compounds (EDTA, 1,10-phenanthroline) and less affected by serine proteinase inhibitors (diisopropylfluorophosphate, phenylmethylsulfonyl fluoride). Proteinase activity was increased by Ca++, Mn++, and Co++, and inhibited by Cu++, Mg++, and Zn++. The activity of this enzyme to hydrolyze casein appeared to be more active on beta-casein than alphas1-casein and kappa-casein as monitored by polyacrylamide gel electrophoresis.

Elective stenting for symptomatic middle cerebral artery stenosis presenting as transient ischaemic deficits or stroke attacks: short term arteriographical and clinical outcome

BACKGROUND

Although stent assisted angioplasty is an effective treatment for coronary and peripheral arterial disease, its efficacy in intracranial arteriosclerotic disease has not been verified.

OBJECTIVES

To assess the radiographic and clinical outcome of stent assisted angioplasty for symptomatic middle cerebral artery (MCA) stenosis.

METHODS

We attempted stent assisted angioplasty in 14 patients with symptomatic high grade stenosis (>60%) on the proximal portion of the MCA, who had experienced either recurrent transient ischaemic attacks (TIAs) resistant to medical therapy or one or more stroke attacks. Patient records were analysed for angiographic characteristics, degree of stenosis, pre-procedural regimen of anti-platelet and/or anti-coagulation agents, use of devices, procedure related complications, pre-operative and post-operative single photon emission computed tomography (SPECT) findings, and clinical and radiographic outcomes.

RESULTS

Stent assisted angioplasty was successfully performed in 8 of 14 patients without any serious complications and unsuccessful in 2 of 14 patients due to the tortuous curve of the internal carotid artery siphon. Four patients had complications. Two patients had an arterial rupture; one patient was rescued by an additional stent and balloon tamponade, the other patient died. Complications in the other two patients included thrombotic occlusion and distal thrombosis. Residual stenosis was less than 50% in diameter in all the patients. All eight patients who underwent follow up cerebral angiography had no restenosis. Follow up SPECT showed improved perfusion in the affected MCA territory in all the tested patients with TIA and in one of three stroke patients. Using the modified Rankin Scale at follow up, four of five TIA patients and five of six stroke patients were assessed as functionally improved or having a stable clinical status.

CONCLUSION

Although the re-stenosis rate in stent assisted angioplasty seems to be better than in primary balloon angioplasty as reported previously, the complication rate is still high. Elective stenting is an alternative therapeutic method for the prevention of secondary ischaemic stroke in stroke patients with MCA stenosis, and seems to be a potentially effective but also hazardous therapeutic technique in patients with recurrent TIAs. This study indicates the need for randomised control trial data of this intervention. Additionally, long term follow up data and additional clinical experience are required to assess the durability of this procedure.

Interrelationships among physicochemical properties, absorption and anthelmintic activities of 2-desoxoparaherquamide and selected analogs

The interrelationships between physicochemical properties, absorption and potency of 2-desoxoparaherquamide and five analogs, representing a new anthelmintic class, were evaluated in in vitro and in vivo assays. At pH 7.5, rates of drug absorption by the gastrointestinal nematode Haemonchus contortus and jird small intestine, parameterized by the permeability coefficient, P(e), ranged from 1.2-2.4 x 10(-4) cm/min (nematode) to 2.5-5.5 x 10(-3) cm/min (jird). In the jird intestine, absorption was pH-dependent, with P(e) at pH 7.5 being twice that at pH 4.5, reflecting the negative influence of protonation on transport of these weakly basic molecules. Each compound rapidly paralyzed H. contortus during in vitro exposure to therapeutically relevant concentrations (1-10 microm). The kinetics of drug action on motility in vivo mirrored their in vitro effects; motility concentrations were reduced in nematodes collected from jird stomach 3 h following oral drug dosing, by which time > or =50% clearance of the parasites had occurred. The nematode/medium partition coefficient K ranged from 10.1 to 16.1, consistent with the lipophilic nature of the compounds. The time required to reduce motility in vitro by 50% (t50*) and P(e) were used to determine C(n)*, the concentration of drug in the nematode at t50*, as an indicator of intrinsic potency. In the jird, the apparent potencies of the compounds were insensitive to route of administration (i.e. oral = i.v. = i.p. = i.m.) for H. contortus and two other gastrointestinal nematodes, Ostertagia ostertagi and Trichostrongylus colubriformis; topical administration, however, required three to 10-fold higher doses for equivalent efficacy.

Attentional bias induced by viewing actual or illusory movements

Objective: To learn to which portions of a line normal subjects would attend when watching this line actually moving or when perceiving movement even in the absence of actual movement, an illusory movement.

Methods: Twenty normal subjects watched a computer monitor on which either lines or dots moved to the right or left. They also watched stationary lines, which appeared to be moving to the left or right because the background was moving in the opposite direction. While watching these lines or dots, their eye movements were monitored to determine the position of fixation.

Results: Overall, subjects fixated on the side of the line that was in the direction of real or illusory movement. In the actual movement condition, leftward motion induced more of an attentional bias than rightward motion. In the illusory movement condition, however, rightward illusory movement condition induced more of an attentional bias than leftward movement.

Conclusions: Objects moving leftward or rightward primarily activate the contralateral hemisphere. This hemispheric activation may induce a contralateral overt orienting response that is reflected by eccentric eye fixation. Treatments of neglect, such as caloric vestibular stimulation, may alter an attentional bias by inducing the illusion of movement.

Purification and characterization of three different types of bile salt hydrolases from Bifidobacterium strains

Bile salt hydrolases were purified to electrophoretic homogeneity from Bifidobacterium bifidum ATCC 11863, Bifidobacterium infantis KL412, Bifidobacterium longum ATCC 15708, Bifidobacterium longum KL507, and Bifidobacterium longum KL515. Three different types (A, B, and C) of bile salt hydrolase (BSH) were revealed during the purification study, exhibiting the type-specific characteristics in their electrophoretic migration and elution profiles from anion exchange and hydrophobic interaction chromatographic columns. The subunit molecular mass estimated by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) was around 35 kDa, and the native molecular mass in all five Bifidobacterium strains was estimated to be between 130 and 150 kDa by gel filtration chromatography, indicating that all BSH enzymes have tetrameric structure. From the isoelectric focusing, an isoelectric point value of 4.45 was obtained with BSH (type B) from B. bifidum ATCC 11863 and the other BSH (types A and C) showed the similar pI values around 4.65. N-Terminal amino acid sequencing for the proteins of types A and C revealed that 6 out of 20 amino acid residues were different, and highly conserved residues were identified in both N-terminal sequences of types A and C. All BSH enzymes from five strains hydrolyzed six major human bile salts, and they showed a better deconjugation rate on glycine-conjugated bile salts than on taurine-conjugated forms.

The Character-line Bisection Task: a new test for hemispatial neglect

A failure to report or respond to stimuli presented in a portion of space is termed hemispatial neglect. Line bisection and line cancellation are two of the tests used most commonly to assess for neglect. Perhaps, because neglect can be induced by a variety of deficits, neither of these tests used alone is as sensitive as both used together. Hence, the primary purpose of this study was to assess the sensitivity, reliability and validity of a new test called the Character-line Bisection Task (CLBT) that combines features of both the bisection and cancellation tests. Since local attention and language are primarily mediated by and activate the left hemisphere, our second goal was to learn if the CLBT and especially the letter version induce a greater rightward bias than the solid-line bisection task. Eighty patients with acute right hemisphere stroke and 81 controls performed the CLBT that consists of two subtests, the Letter-line and Star-line Bisection tasks. All subjects also completed four conventional tests for neglect (Standard solid-line bisection, line cancellation, Star Cancellation, and figure copying). In the bisection tasks both patients and controls bisected to the right with the CLBT than with the solid-line bisection task, suggesting the CLBT induces asymmetrical hemispheric activation. This enhanced rightward deviation with the CLBT was the same for the Letter-line and Star-line Bisection tasks. In regard to sensitivity, we defined the presence of neglect syndrome based on a total score derived from performance of controls on all six tests. This total score detected 55 (68.8%) patients with neglect. Within this group, the Letter-line and Star-line tasks diagnosed neglect in 50 and 48 patients, respectively, resulting in the highest sensitivities (90.9, 87.3%) of the six tests. Thus, the CLBTs demonstrated higher sensitivities than the other commonly used neglect tests and these new tests can be useful for the detection and quantification of unilateral neglect.

Effect of subthalamic lesion with kainic acid on the neuronal activities of the basal ganglia of rat parkinsonian models with 6-hydroxydopamine

The aim of the present study was to investigate the alteration of neuronal activities in the substantia nigra pars reticulata (SNpr) and globus pallidus (GP), after ipsilateral STN lesioning by kainic acid in the rat hemi-parkinsonian 6-hydroxydopamine (6-OHDA) model. In various rat Parkinson's disease (PD) models, an increase in the SNpr firing rate was observed, despite the occurrence of bursting patterns, and subthalamic lesion was found to reduce the mean firing rates and the percentage of bursting neurons in the SNpr. However, the relative proportion of bursting neurons, among all GP neurons, was slightly increased as a result of the subthalamic lesion. The significance of bursting activity in the SNpr and GP remains obscure. Further study is necessary to elucidate the pathophysiological mechanism behind Parkinson's disease.

Wax moth, Galleria mellonella, high density lipophorin receptor: alternative splicing, tissue-specific expression, and developmental regulation

A lipophorin (Lp) receptor cDNA from the fat body of Galleria mellonella (Lepidoptera) was cloned and sequenced. This is the first result in this order, Lepidoptera. It showed the pattern of the VLDL receptor belonging to the LDL receptor family. Sequence homology with other Lp receptors in insects, Locusta migratoria and Aedes aegypti, was 70 and 61%, respectively and each domain was highly conserved. Polyclonal anti-Lp receptor antibody prepared against expressed Lp receptor fragment between ligand binding domain and EGF-precursor homology domain (R305-D549 of amino acid residues) specifically detected the Lp receptor. Through immuno-blotting, the Lp receptor of larval fat body has an approximate molecular mass of about 97 and 110 kDa under non-reducing and reducing conditions, respectively. This result was in agreement with that of the ligand-blotting. The variant Lp receptors were expressed in the fat body of G. mellonella; one is an Lp receptor which lacks 84 bp of O-linked sugar domain and the other is a full length form of the Lp receptor. Both forms were detected by the polyclonal anti-Lp receptor antibody. The Lp receptor from the fat body of G. mellonella was differently expressed depending on the tissue and the developmental stage with specific abundance in prepupal stage. A steroid hormone, 20-hydroxyecdysone (20-HE) plays a crucial role in insect development. With regards to this conception, day 1-2 last instar larvae were treated with 20-HE and drastic induction of the Lp receptor was observed 48 h after treatment. It was also observed that cholesterol caused an induction of the Lp receptor.

Endovascular rescue from arterial rupture and thrombosis during middle cerebral artery stenting

Intravascular stents are being used with increasing frequency in interventional neuroradiology. Iatrogenic arterial rupture is an uncommon but serious complication. We present a case of arterial rupture and subarachnoid haemorrhage during middle cerebral artery stenting, treated by emergency additional, overlapping stenting and balloon tamponade of the dissected vessel. Thrombotic occlusion of the artery was managed by intra-arterial abciximab. Normal vessel patency was re-established within 20 min and the patient recovered with no neurological deficit.

The Cdc14 phosphatase and the FEAR network control meiotic spindle disassembly and chromosome segregation

During meiosis, DNA replication is followed by two consecutive rounds of chromosome segregation. Cells lacking the protein phosphatase CDC14 or its regulators, SPO12 and SLK19, undergo only a single meiotic division, with some chromosomes segregating reductionally and others equationally. We find that this abnormal chromosome behavior is due to an uncoupling of meiotic events. Anaphase I spindle disassembly is delayed in cdc14-1, slk19Delta, or spo12Delta mutants, but the chromosome segregation cycle continues, so that both meiotic chromosome segregation phases take place on the persisting meiosis I spindle. Our results show that Cdc14, Slk19, and Spo12 are not only required for meiosis I spindle disassembly but also play a pivotal role in establishing two consecutive chromosome segregation phases, a key feature of the meiotic cell cycle.

Identification of an encystation-specific transcription factor, Myb protein in Giardia lamblia

The life cycle of Giardia lamblia contains two differentiation processes, encystation and excystation. We performed an experiment to identify the genes induced during encystation using the differential display reverse transcriptase-polymerase chain reaction. Three of twelve isolated cDNA clones that showed increased transcription during encystation were identified to be of the myb2, which encodes a well-known transcriptional factor involved in cellular development and differentiation. The amino acid sequences of the Myb2 protein deduced from the isolated gene revealed that this Myb2 has a DNA binding domain comprising two imperfect repeats at its carboxyl-terminus. The nuclear localization of Myb2 protein during encystation was observed in vivo by expressing a Myb2-GFP fusion protein. In a random site selection experiment, the oligonucleotides bound by rMyb2 contained a conserved sequence of GTTT(G/T)(G/T). Two promoters of the encystation-induced genes, myb2, and cwp1, were also found to bind to rMyb2, whereas gap1, one of the constitutive genes did not.

Role of Polo-like kinase CDC5 in programming meiosis I chromosome segregation

Meiosis is a specialized cell division in which two chromosome segregation phases follow a single DNA replication phase. The budding yeast Polo-like kinase Cdc5 was found to be instrumental in establishing the meiosis I chromosome segregation program. Cdc5 was required to phosphorylate and remove meiotic cohesin from chromosomes. Furthermore, in the absence of CDC5 kinetochores were bioriented during meiosis I, and Mam1, a protein essential for coorientation, failed to associate with kinetochores. Thus, sister-kinetochore coorientation and chromosome segregation during meiosis I are coupled through their dependence on CDC5.