Evolution of immune and stromal cell states and ecotypes during gastric adenocarcinoma progression

Understanding tumor microenvironment (TME) reprogramming in gastric adenocarcinoma (GAC) progression may uncover novel therapeutic targets. Here, we performed single-cell profiling of precancerous lesions, localized and metastatic GACs, identifying alterations in TME cell states and compositions as GAC progresses. Abundant IgA+ plasma cells exist in the premalignant microenvironment, whereas immunosuppressive myeloid and stromal subsets dominate late-stage GACs. We identified six TME ecotypes (EC1-6). EC1 is exclusive to blood, while EC4, EC5, and EC2 are highly enriched in uninvolved tissues, premalignant lesions, and metastases, respectively. EC3 and EC6, two distinct ecotypes in primary GACs, associate with histopathological and genomic characteristics, and survival outcomes. Extensive stromal remodeling occurs in GAC progression. High SDC2 expression in cancer-associated fibroblasts (CAFs) is linked to aggressive phenotypes and poor survival, and SDC2 overexpression in CAFs contributes to tumor growth. Our study provides a high-resolution GAC TME atlas and underscores potential targets for further investigation.

O-315 A war in Europe?: Ukrainian scientists' struggle for life and future, relocation and securing of frozen biomaterials

We should describe war as an attack maneuver by two countries or organizations against each other in line with their mutual interests when giving it significance. What is going on in Ukraine is more than a war; it is people's effort to defend their future, past from this genocide attacks which done by Russian Federation.

Russian Federation’s attacks not only damage all healthcare and scientific institutions but also make any future advancement in healthcare impossible. Millions of Ukrainians and foreigners residing, working, and living in the country were uprooted and forced to flee. While the strikes rendered general healthcare and fertility services inoperable, they also made protecting and maintaining all stored gametes and embryos challenging. Many infertility patients and thousands of IVF couples who have undergone oncofertility cryopreservation have been put at risk due to these attacks.

While what happened in Ukraine affects thousands of infertility patients worldwide, the horrific situations faced by hundreds of IVF specialists, embryologists, nurses, and other allied healthcare workers, along with the losses they have suffered and the uncertainty of their future, reveal that the situation is far more than a war and that it is a genocide situation that no one who values life should accept.

Embryologists were trying to freeze embryos and gametes at different developmental stages of dozens of patients in their incubators on February 24, when the Russian Federation’s attacks started, ignoring the vital risks, again, on the day of the war beginning, and IVF specialists who performed egg collection and embryo transfer procedures for all patients who were in that day before, as well as all the other healthcare workers who took part in this process — they all showed how professionally and willingly the IVF service in Ukraine is provided. When the attacks became more intense in the days ahead, hundreds of Ukrainian embryologists risked their lives and the lives of their families to transport frozen samples to secure regions within the country and even beyond, sending a powerful message to the entire world.

Expert embryologists moved all frozen components to secure locations, adhering to all safety regulations and regularly monitoring temperature and liquid nitrogen levels. It is impossible to say that this transportation method is not at risk from attacks. The transfer process was carried out fully to protect patients, with individual decisions made without acquiring patient consent forms or essential approvals due to the urgency of the decisions made from the moment the attacks had begun.

The samples obtained abroad, on the other hand, were transported to European countries after all of the necessary legal registrations and procedures were completed at customs, following long and exhausting land journeys. Storage tanks that can be transferred within Ukraine were moved to western cities and secured in clinics with medical licenses. Samples were also secured in clinics with medical licenses outside of Ukraine, and all essential legal documents and regulations were completed.

While over 70,000 frozen embryos have been carried abroad, over 10,000 frozen eggs have been transported for egg banking. Thousands of testicular tissue samples and hundreds of ovarian tissue samples were also transported. In Ukraine, thousands of frozen embryo and sperm samples are now successfully preserved. So far, no embryo harm or difficulties with liquid nitrogen delivery have been recorded. However, if Russian Federation’s attacks continue, the difficulties will inevitably worsen, putting hundreds of frozen patient samples in danger.

Hundreds of embryologists, IVF specialists, nurses, and paramedics were also laid off, and many were forced to flee the country. The Russian Federation’s attacks on the Ukrainian people have put human lives and the future prospects of countless infertility patients in jeopardy.

P-085 Use of an artificial intelligence tool to assess single-sperm motility variables related to bias preference of ICSI sperm selection practice, normal fertilization, and blastocyst formation

Study question

Which single-sperm WHO motility variables are associated with ICSI sperm selection preference, normal fertilization, and blastocyst formation when assessed by an artificial intelligence platform?

Summary answer

Injected sperm had higher VSL, VAP, and LIN compared with non-injected. Higher STR was associated with fertilization and higher WOB and less HMP with blastulation.

What is known already

Sperm selection for intracytoplasmic sperm injection (ICSI) is key to its success. Currently, the procedure may be subjective although the embryologist selects rapidly from a small population of sperm. There is no consensus on specific motility variables for single-sperm selection.

SiD (IVF 2.0 Limited, UK) software is able to assess all sperm in a visual field and accurately compute the motility variables for each sperm in real-time. SiDTM could help to understand the association between motility variables related to ICSI success and to assess the differences in sperm selection practice between different clinics and operators.

Study design, size, duration

473 ICSI videos and their corresponding outcome were retrospectively analyzed using SiD software and assessed against normal fertilization (2PN), and blastocyst formation (BF), from four fertility clinics in different countries between July 2021 to December 2021. Ethical approval was obtained. This study was non-interventional. The study parameters were defined as sperm that were selected or non-selected, 2PN, and BF.

Participants/materials, setting, methods

Motility variables were computed from ICSI videos for VSL, VCL, LIN, VAP, ALH, WOB, STR as defined by the WHO manual for the examination and processing of human semen; and HMP, a metric associated with sperm-head movements. Injected sperm were manually identified and the injection was visually verified by a senior embryologist. Extracted motility variables were standardized according to each clinic and PVP concentration. Study groups were tested with a two-sided Mann-Whitney U test.

Main results and the role of chance

Video analysis identified 304 selected and 9543 non-selected sperm. 2PN and BF status was known for 302 and 301 injected oocytes respectively (2PN rate: 79%, BF rate: 53%).

Embryologists used VSL, VAP, and LIN as the preferred motility criteria to select sperm (p < 0.001). Using data from all clinics, we found a tendency for STR (p = 0.12) and LIN (p = 0.14) for 2PN and WOB (p = 0.11) and VAP (p = 0.18) for BF.

There was partial consistency on sperm selection criteria amongst clinics: Clinic1 selected VSL, VAP, and LIN as the main variables to select sperm; Clinic2 VSL, WOB, and LIN; Clinic3 VSL, VAP, and VCL; and Clinic4 ALH, VCL, and VAP (p < 0.001).

For Clinic1 higher HMP showed a correlation (p = 0.06, n = 21) to 2PN, while higher WOB (p = 0.12, n = 21) did for BF. Clinic2 showed a limited association to higher STR and 2PN (p = 0.12, n = 120), and a significant association between higher WOB and BF (p < 0.05, n = 120). Clinic3’s data suggested that higher STR was associated with 2PN (p < 0.05, n = 97) and low HMP with BF (p < 0.05, n = 97).

Limitations, reasons for caution

This retrospective study needs to be repeated prospectively with larger numbers in more locations using embryologists with different levels of ICSI experience. Clinical outcome data such as clinical pregnancy, miscarriage, and live birth impact is still required.

Wider implications of the findings

SiD was able to track and extract motility features from single sperm. SiDTM could assist embryologists in real-time to select sperm during ICSI and could be used as a training tool to reduce variability among embryologists.

Trial registration number

RPA-2021-03

Assessing physical activity in people with mental illness: 23-country reliability and validity of the simple physical activity questionnaire (SIMPAQ)

BACKGROUND

Physical inactivity is a key contributor to the global burden of disease and disproportionately impacts the wellbeing of people experiencing mental illness. Increases in physical activity are associated with improvements in symptoms of mental illness and reduction in cardiometabolic risk. Reliable and valid clinical tools that assess physical activity would improve evaluation of intervention studies that aim to increase physical activity and reduce sedentary behaviour in people living with mental illness.

METHODS

The five-item Simple Physical Activity Questionnaire (SIMPAQ) was developed by a multidisciplinary, international working group as a clinical tool to assess physical activity and sedentary behaviour in people living with mental illness. Patients with a DSM or ICD mental illness diagnoses were recruited and completed the SIMPAQ on two occasions, one week apart. Participants wore an Actigraph accelerometer and completed brief cognitive and clinical assessments.

RESULTS

Evidence of SIMPAQ validity was assessed against accelerometer-derived measures of physical activity. Data were obtained from 1010 participants. The SIMPAQ had good test-retest reliability. Correlations for moderate-vigorous physical activity was comparable to studies conducted in general population samples. Evidence of validity for the sedentary behaviour item was poor. An alternative method to calculate sedentary behaviour had stronger evidence of validity. This alternative method is recommended for use in future studies employing the SIMPAQ.

CONCLUSIONS

The SIMPAQ is a brief measure of physical activity and sedentary behaviour that can be reliably and validly administered by health professionals.

A complex four-point method for the evaluation of ohmic and faradaic losses within a redox flow battery single-cell

We propose a complex 4-point method for characterization of flow batteries. The distribution of ohmic and faradaic losses within a single-cell is evaluated from electrochemical impedance spectra and load curves of positive and negative half-cells measured with platinum wire pseudo-reference electrodes positioned in respective electrode compartment. The developed method can be used e.g., for the component screening and in-situ durability studies on single-cell scale. The method was validated on a vanadium redox flow battery single-cell; however, it can be analogically employed for various chemistries of flow battery. •Complex 4-point method for characterization of flow battery single-cell was developed.•Method is based on electrochemical impedance spectra and load curve measurements.•Direct evaluation of ohmic and faradaic losses distribution within battery single-cell by the method.

Factors influencing quality of anticoagulation control and warfarin dosage in patients after aortic valve replacement within the 3 months of follow up

Warfarin dosage estimation using the pharmacogenetic algorithms has been shown to improve the quality of anticoagulation control in patients with atrial fibrillation. We sought to assess the genetic, demographic and clinical factors that determine the quality of anticoagulation in patients following aortic valve replacement (AVR). We studied 200 consecutive patients (130 men) aged 63 ± 12.3 years, undergoing AVR, in whom warfarin dose was established using a pharmacogenetic algorithm. The quality of anticoagulation within the first 3 months since surgery was expressed as the time of international normalized ratio (INR) in the therapeutic range (TTR). The median TTR in the entire cohort was 59.6% (interquartile range, 38.7 - 82.7). Ninety-nine (49.5%) patients with TTR ≥ 60% did not differ from those with poor anticoagulation control (TTR < 60%) with regard to demographic and cardiovascular risk factors. Coronary artery disease (n = 84, 42%) and previous stroke (n = 5, 2.5%) predicted higher TTR, while possession of CYP2C9*2 variant allele (n = 49, 25%) was associated with lower TTR (P = 0.01). In turn, VKORC1 c.-1639A, CYP2C9*2 and *3 variants were independently associated with actual warfarin dose (P < 0.0001). In AVR patients better anticoagulation control is observed in patients with coronary artery disease and history of stroke, which might result in part from previous lifestyle modification and therapy. Possession of CYP2C9*2 and/or CYP2C9*3 allele variants is associated with lower TTR values and warfarin dose variations in AVR patients, the latter affected also by VKORC1 c.-1693G>A polymorphism.

Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus-the 'D-shuttle' project

Twelve high schools in Japan (of which six are in Fukushima Prefecture), four in France, eight in Poland and two in Belarus cooperated in the measurement and comparison of individual external doses in 2014. In total 216 high-school students and teachers participated in the study. Each participant wore an electronic personal dosimeter 'D-shuttle' for two weeks, and kept a journal of his/her whereabouts and activities. The distributions of annual external doses estimated for each region overlap with each other, demonstrating that the personal external individual doses in locations where residence is currently allowed in Fukushima Prefecture and in Belarus are well within the range of estimated annual doses due to the terrestrial background radiation level of other regions/countries.

Influence of the surface properties on bactericidal and fungicidal activity of magnetron sputtered Ti-Ag and Nb-Ag thin films

In this study the comparative investigations of structural, surface and bactericidal properties of Ti-Ag and Nb-Ag thin films have been carried out. Ti-Ag and Nb-Ag coatings were deposited on silicon and fused silica substrates by magnetron co-sputtering method using innovative multi-target apparatus. The physicochemical properties of prepared thin films were examined with the aid of X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy methods. Moreover, the wettability of the surface was determined. It was found that both, Ti-Ag and Nb-Ag thin films were nanocrystalline. In the case of Ag-Ti film presence of AgTi3 and Ag phases was identified, while in the structure of Nb-Ag only silver occurred in a crystal form. In both cases the average size of crystallites was ca. 11 nm. Moreover, according to scanning electron microscopy and atomic force microscopy investigations the surface of Nb-Ag thin films was covered with Ag-agglomerates, while Ti-Ag surface was smooth and devoid of silver particles. Studies of biological activity of deposited coatings in contact with Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus hirae, Klebisiella pneumoniae, Escherichia coli, Staphylococcus aureus and Candida albicans were performed. It was found that prepared coatings were bactericidal and fungicidal even in a short term-contact, i.e. after 2 h.

Dehydration Preparation of Mouse Sperm for Vitrification and Rapid Laser Warming

BACKGROUND

Mice are fundamental models of study due to their ease of breeding, manipulation, and the well-studied genome. There has been extensive research focused on the cryopreservation of mouse germaplasm, as a way to help maintain the different transgenic mouse breeds. The first protocols for mouse sperm were developed in the 90's using slow cooling and a mixture of raffinose and glycerol. Since then, the rate of success reported remains highly variable.

OBJECTIVE

The Aim of this work is to study factors that are key for developing vitrification protocols for ultra-rapid laser warming of mouse sperm.

RESULTS

Our results show that due to the exquisite sensitivity of sperm cells to osmotic excursions, our target levels of dehydration (~85% water content) cannot be achieved without causing a significant decrease in sperm motility and membrane fusion.

CONCLUSION

It seems likely that mouse sperm vitrification is going to be difficult to develop due to the exquisite sensitivity of mouse sperm cells to handling and dehydration.

Abstract IA02: A drug repositioning approach identifies tricyclic antidepressants as inhibitors of small cell lung cancer

Small cell lung carcinoma (SCLC) is highly aggressive and metastatic neuroendocrine lung cancer with a dismal 5-year survival. While a majority of patients is initially responsive to chemotherapy, chemoresistant tumors rapidly recur. There are no approved targeted therapies for SCLC. We used a systematic drug-repurposing computational approach querying a large number of gene expression datasets to identify new candidate FDA-approved drugs that may be used to treat SCLC. This analysis identified tricyclic antidepressants (TCAs) and related molecules as possible inhibitors of SCLC. Indeed, these compounds potently induce apoptotic cell death in chemonaïve and chemoresistant tumor cells in culture, in a genetically engineered mouse model, and in human SCLC tumor cells transplanted into immunocompromised mice. Imipramine and Promethazine, the two top candidate drugs, activate stress pathways and induce apoptosis and necrosis in SCLC cells, in part by blocking autocrine survival signals involving neurotransmitters and their receptors (GPCRs). The candidate drugs inhibit the expansion of other neuroendocrine tumors, including pancreatic neuroendocrine tumors. These experiments underscore the power of bioinformatics-based drug-repositioning approaches to rapidly repurpose FDA-approved drugs and identify a novel class of candidate molecules to treat patients with SCLC. In addition, our experiments highlight the importance of autocrine mechanisms promoting the growth of neuroendocrine tumor cells.

Citation Format: Nadine Jahchan, Dudley Joel, Pawel Mazur, Joel Neal, Purvesh Khatri, Atul Butte, Julien Sage. A drug repositioning approach identifies tricyclic antidepressants as inhibitors of small cell lung cancer. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr IA02.

Nɛ-homocysteinyl-lysine isopeptide is associated with progression of peripheral artery disease in patients treated with folic acid

OBJECTIVE

Folic acid (FA) administration can reduce plasma total homocysteine (tHcy); however, it fails to decrease cardiovascular events and progression of peripheral artery disease (PAD). Nɛ-homocysteinyl-lysine isopeptide (Nɛ-Hcy-Lys) is formed during catabolism of homocysteinylated proteins. We sought to investigate factors that determine the presence of Nɛ-Hcy-Lys in PAD patients with hyperhomocysteinemia receiving FA.

PATIENTS AND METHODS

We studied 131 consecutive PAD patients with tHcy > 15 μmol l(-1) taking FA 0.4 mg d(-1) for 12 months. Serum Nɛ-Hcy-Lys was determined by high-performance liquid chromatography (HPLC). We also measured interleukin-6 (IL-6), plasminogen activator inhibitor-1 (PAI-1), asymmetric dimethylarginine (ADMA) and 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)).

RESULTS

FA administration resulted in a 70.5% decrease in tHcy (p < 0.0001). However, serum Nɛ-Hcy-Lys was detectable in 28 (21.4%) patients on FA who were more frequently current smokers and survivors of ischaemic stroke (p < 0.001). They had higher tHcy by 46.0%, PAI-1 by 51.7%, 8-iso-PGF(2α) by 59.1% and ADMA by 26.4% (all, p < 0.0001). The presence of Nɛ-Hcy-Lys was associated with lower ankle-brachial index (ABI) values (p < 0.001) and higher prevalence of cardiovascular events (p < 0.001) following therapy.

CONCLUSION

The presence of Nɛ-Hcy-Lys in one-fifth of hyperhomocysteinemic individuals with PAD despite FA treatment is associated with progression of PAD and with increased ADMA formation, oxidative stress and hypofibrinolysis.

Does molecular docking reveal alternative chemopreventive mechanism of activation of oxidoreductase by sulforaphane isothiocyanates?

Isothiocyanates (ITC) are well-known chemopreventive agents extracted from vegetables. This activity results from the activation of human oxidoreductase. In this letter, the uncompetitive activatory mechanism of ITC was investigated using docking and molecular dynamics simulations. This indicates that NAD(P)H:quinone oxidoreductase can efficiently improve enzyme-substrate recognition within the catalytic site if the ITC activator supports the interaction in the uncompetitive binding site.

Coral larvae conservation: Physiology and reproduction

Coral species throughout the world's oceans are facing severe environmental pressures. We are interested in conserving coral larvae by means of cryopreservation, but little is known about their cellular physiology or cryobiology. These experiments examined cryoprotectant toxicity, dry weight, water and cryoprotectant permeability using cold and radiolabeled glycerol, spontaneous ice nucleation temperatures, chilling sensitivity, and settlement of coral larvae. Our two test species of coral larvae, Pocillopora damicornis (lace coral), and Fungia scutaria (mushroom coral) demonstrated a wide tolerance to cryoprotectants. Computer-aided morphometry determined that F. scutaria larvae were smaller than P. damicornis larvae. The average dry weight for P. damicornis was 24.5%, while that for F. scutaria was 17%, yielding osmotically inactive volumes (V(b)) of 0.22 and 0.15, respectively. The larvae from both species demonstrated radiolabeled glycerol uptake over time, suggesting they were permeable to the glycerol. Parameter fitting of the F. scutaria larvae data yielded a water permeability 2 microm/min/atm and a cryoprotectant permeability = 2.3 x 10(-4) cm/min while modeling indicated that glycerol reached 90% of final concentration in the larvae within 25 min. The spontaneous ice nucleation temperature for F. scutaria larvae in filtered seawater was -37.8+/-1.4 degrees C. However, when F. scutaria larvae were chilled from room temperature to -11 degrees C at various rates, they exhibited 100% mortality. When instantly cooled from room temperature to test temperatures, they showed damage below 10 degrees C. These data suggest that they are sensitive to both the rate of chilling and the absolute temperature, and indicate that vitrification may be the only means to successfully cryopreserve these organisms. Without prior cryopreservation, both species of coral settled under laboratory conditions.

High ice nucleation temperature of zebrafish embryos: slow-freezing is not an option

Although fish embryos have been used in a number of slow-freezing cryopreservation experiments, they have never been successfully cryopreserved. In part this is because little is known about whether ice forms within the embryo during the slow-freezing dehydration process. Therefore, we examined the temperature of intraembryonic ice formation (T(IIF)) and the temperature of extraembryonic ice formation (T(EIF)), using a cryomicroscope. We used both unmodified zebrafish embryos and those with water channels (aquaporin-3 or AQP3) inserted into their membranes to increase permeability to water and cryoprotectants, examined at 100% epiboly to the 6-somite stage. In these experiments we examined: (1) the spontaneous freezing of (external) solutions; (2) the spontaneous freezing of solutions containing embryos; (3) the effect of preloading the embryos with cryoprotectants on T(IIF); (4) whether preloading the embryos with cryoprotectant helps in survival after nucleating events in the solution; and (5) the damaging effects of extracellular nucleation events versus solution toxicity on the embryos. The solutes alone (embryo medium--EM, sucrose culture medium, 1 M propylene glycol in EM, and 1 M propylene glycol in a sucrose culture medium) froze at -14.9 +/- 1.1, -17.0 +/- 0.3, -17.8 +/- 1.0, and -17.7 +/- 1.4, respectively. There was no difference amongst these means (P > 0.05), thus adding cryoprotectant did not significantly lower the nucleation point. Adding embryos (preloaded with cryoprotectant or not) did not change the basic freezing characteristics of these solutes. In all these experiments, (T(EIF)) equaled (T(IIF)), and there was no difference in the freezing point of the solutions with or without the embryos (P > 0.05). Additionally, there was no difference in the freezing characteristics of embryos with and without aquaporins (P > 0.05). The formation of intraembryonic ice was lethal to the zebrafish embryos in all cases. But this lethal outcome was not related to solution injury effects, because 88-98% of embryos survived when exposed to a higher solute concentration with no ice present. Taken together, these data suggest that slow-freezing is not a suitable option for zebrafish embryos. The mechanism of this high temperature nucleation event in zebrafish embryos is still unknown.

Effect of osmolality and oxygen tension on the survival of mouse sperm frozen to various temperatures in various concentrations of glycerol and raffinose

Cryopreserved mouse sperm are beginning to be used to meet the demand of a reliable cost-effective method for maintaining the rapidly expanding numbers of lines of mutant mice. However, successful and reproducible cryopreservation has proven to be a difficult problem. Furthermore, the underlying factors responsible for success or failure are mostly obscure. Several contributors to these difficulties have been identified. Our laboratory has found that mouse sperm are extremely susceptible to the mechanical stresses associated with pipetting, mixing, and centrifugation, and others have found that they are severely limited in their tolerance to osmotic volume changes. We have hypothesized two other contributors to the difficulties. One is that the concentrations of glycerol used in published protocols are substantially lower than those found to be optimal for most mammalian cells. The other hypothesis relates to the fact that mouse sperm membranes are especially susceptible to damage from oxygen-derived free radicals. That damage may reduce their ability to survive freezing. If so, survival ought to increase if the concentration of oxygen is kept low throughout the procedure. To achieve low levels, we have incorporated an Escherichia coli membrane fraction, Oxyrase, into all media. A previous report showed a protective effect. That is confirmed here under a broader range of conditions. The conditions studied have been the individual and interactive effects of the concentrations of glycerol, raffinose, and phosphate-buffered saline (PBS) on motility after freezing at 21 degrees C/min to -70 degrees C. Cryoprotection increased with increasing raffinose concentration, provided that the concentration of PBS was appropriately reduced to hold the total osmolality of nonpermeating solutes to within tolerated limits. Surprisingly, the best results were achieved in the total absence of glycerol. The highest motilities to date (68 +/- 8%) after freezing to -70 degrees C have been achieved using media containing Oxyrase, 0 M glycerol, and 18% raffinose in 14x strength modified PBS. We also determined the motility loss after freezing to intermediate temperatures, i.e., -10 and -30 degrees C. The major motility loss occurred by -10 degrees C, especially in the absence of Oxyrase. These results suggest that a major problem in the freezing of mouse sperm is the physical stress resulting from extracellular ice crystal formation. Oxyrase appears to lessen that damage substantially.

Expression and characterization of protein geranylgeranyltransferase type I from the pathogenic yeast Candida albicans and identification of yeast selective enzyme inhibitors

Protein geranylgeranyltransferase type I (GGTase I) is a heterodimeric zinc metalloenzyme catalyzing protein geranylgeranylation at cysteine residues present in C-terminal signature sequences referred to as CaaX (X=Leu) motifs. We have studied GGTase I as a potential antifungal target and recently reported its purification and cloning from the yeast Candida albicans (Ca GGTase I), an important human pathogen. Here, we report the high yield bacterial expression of Ca GGTase I by coexpression of maltose binding protein fusion proteins of both the alpha (Ram2p) and beta (Cdc43p) subunits. The cleaved and purified recombinant Ca GGTase I was demonstrated to be functional and structurally intact as judged by the presence of one equivalent of a tightly bound zinc atom and the near stoichiometric formation, isolation and catalytic turnover of a geranylgeranyl pyrophosphate-GGTase I complex. Kinetic analysis was performed with a native substrate protein, Candida Cdc42p, which exhibited significant pH dependent substrate inhibition, a feature not observed with other Ca GGTase I substrates. Prenyl acceptor substrate specificity was studied with a series of peptides in which both the CaaX motif, and the sequence preceding it, were varied. The prenyl acceptor K(M)s were found to vary nearly 100-fold, with biotinyl-TRERKKKKKCVIL, modeled after a presumably geranylgeranylated Candida protein, Crl1p (Rho4p), being the optimal substrate. A screen for inhibitors of Ca GGTase I identified compounds showing selectivity for the Candida versus human GGTase I. The most potent and selective compound, L-689230, had an IC(50) of 20 nM and >12,500-fold selectivity for Ca GGTase I. The lack of significant anti-Candida activity for any of these inhibitors is consistent with the recent finding that GGTase I is not required for C. albicans viability [R. Kelly et al., J. Bacteriol. 182 (2000) 704-713].

Factors affecting yield and survival of cells when suspensions are subjected to centrifugation. Influence of centrifugal acceleration, time of centrifugation, and length of the suspension column in quasi-homogeneous centrifugal fields

The goals of the centrifugation of cell suspensions are to obtain the maximum yield of cells with minimum adverse effects of centrifugation. In the case of mechanically sensitive cells such as mouse sperm, the two goals are somewhat contradictory in that g-forces sufficient to achieve high yields are damaging, and g-forces that yield high viability produce low yields. This paper mathematically analyzes the factors contributing to each goal. The total yield of pelleted cells is determined by the sedimentation rate governed by Stokes' Law, and depends on the relative centrifugal force, centrifugation time, size and shape of the cells, density of the cells and medium, viscosity of the medium, and the length of the column of suspension. Because in the situation analyzed the column is short relative to the rotor radius, the analysis considers the centrifugal field to be quasi-homogeneous. The assumption is that cells are not damaged during sedimentation, but that they become injured at an exponential rate once they are pelleted, a rate that will depend on the specific cell type. The behavior is modeled by the solution of coupled differential equations. The predictions of the analysis are in good agreement with experimental data on the centrifugation of mouse sperm.

The enhancement of the ability of mouse sperm to survive freezing and thawing by the use of high concentrations of glycerol and the presence of an Escherichia coli membrane preparation (Oxyrase) to lower the oxygen concentration

The cryobiological preservation of mouse spermatozoa has presented difficulties in the form of poor motilities or irreproducibility. We have hypothesized several underlying problems. One is that published studies have used concentrations of the cryoprotectant glycerol that are substantially lower (<0.3 M) than the approximately 1 M concentrations that are optimal for most mammalian cells. Another may arise from the known high susceptibility of mouse sperm to free radical damage. We have been able to obtain high motilities in 0.8 M glycerol provided that the exposure time is held to approximately 5 min to minimize toxicity and provided that the glycerol is added and removed stepwise to minimize osmotic shock. Since free radical damage in mouse sperm is proportional to the oxygen concentrations, we have determined the consequences of reducing the oxygen to <3% of atmospheric by maintaining the sperm in contact with an Escherichia coli membrane preparation, Oxyrase, from the moment of collection throughout the assessment of motility. Prior studies have shown that the procedure significantly reduces damage from centrifugation and osmotic shock. In the experiments reported here we obtained approximately 50% motility relative to untreated controls when suspensions containing 3.8% Oxyrase were exposed approximately 5 min to a solution of 0.8 M glycerol and 0.17 M (10%) raffinose in a supplemented PBS and then frozen at approximately 25 degrees C/min to -75 degrees C. In the absence of Oxyrase, the normalized motility dropped to 31%. The protection by Oxyrase was in part a consequence of minimizing centrifugation damage, but in part it reflected a reduction in freeze-thaw damage. Preliminary experiments indicate that the number of motile sperm after cryopreservation in Oxyrase is higher when the sperm are collected without swim-up than when they are collected by swim-up. This is in part due to the fact that more cells are collected in the absence of swim-up and in part due to a greater protective effect of Oxyrase on those cells. The minimum temperature in these initial experiments was limited to -75 degrees C to avoid the potential contribution of other injurious factors between -75 and -196 degrees C.

Geranylgeranyltransferase I of Candida albicans: null mutants or enzyme inhibitors produce unexpected phenotypes

Geranylgeranyltransferase I (GGTase I) catalyzes the transfer of a prenyl group from geranylgeranyl diphosphate to the carboxy-terminal cysteine of proteins with a motif referred to as a CaaX box (C, cysteine; a, usually aliphatic amino acid; X, usually L). The alpha and beta subunits of GGTase I from Saccharomyces cerevisiae are encoded by RAM2 and CDC43, respectively, and each is essential for viability. We are evaluating GGTase I as a potential target for antimycotic therapy of the related yeast, Candida albicans, which is the major human pathogen for disseminated fungal infections. Recently we cloned CaCDC43, the C. albicans homolog of S. cerevisiae CDC43. To study its role in C. albicans, both alleles were sequentially disrupted in strain CAI4. Null Cacdc43 mutants were viable despite the lack of detectable GGTase I activity but were morphologically abnormal. The subcellular distribution of two GGTase I substrates, Rho1p and Cdc42p, was shifted from the membranous fraction to the cytosolic fraction in the cdc43 mutants, and levels of these two proteins were elevated compared to those in the parent strain. Two compounds that are potent GGTase I inhibitors in vitro but that have poor antifungal activity, J-109,390 and L-269,289, caused similar changes in the distribution and quantity of the substrate. The lethality of an S. cerevisiae cdc43 mutant can be suppressed by simultaneous overexpression of RHO1 and CDC42 on high-copy-number plasmids (Y. Ohya et al., Mol. Biol. Cell 4:1017, 1991; C. A. Trueblood, Y. Ohya, and J. Rine, Mol. Cell. Biol. 13:4260, 1993). Prenylation presumably occurs by farnesyltransferase (FTase). We hypothesize that Cdc42p and Rho1p of C. albicans can be prenylated by FTase when GGTase I is absent or limiting and that elevation of these two substrates enables them to compete with FTase substrates for prenylation and thus allows sustained growth.

Mouse spermatozoa in high concentrations of glycerol: chemical toxicity vs osmotic shock at normal and reduced oxygen concentrations

The cryobiological preservation of mouse spermatozoa has presented difficulties in the form of poor motilities or irreproducibility. We have identified several likely underlying problems. One is that published studies have used concentrations of the cryoprotectant glycerol that are substantially lower (0.3 M) than the approximately 1 M concentrations that are optimal for most cells. Another may arise from the known high susceptibility of mouse sperm to free radical damage. We have identified two contributors to damage from higher concentrations of glycerol, namely, chemical toxicity proportional to concentration and exposure time and osmotic damage arising from too rapid an addition and removal of the glycerol. When toxicity is minimized by restricting the exposure time to 1 or 5 min and osmotic shock is minimized by adding and removing the glycerol stepwise, relatively high percentages of the sperm survive contact with 0.8 M glycerol. Free-radical damage in mouse sperm is known to be proportional to the oxygen concentration. We have determined the consequences of reducing the oxygen to <3% of atmospheric by the use of a bacterial membrane preparation, Oxyrase. Oxyrase reduced damage from centrifugation and substantially reduced damage from osmotic shock; however, it did not significantly reduce glycerol toxicity.

Loss of the plasma membrane-bound protein Gas1p in Saccharomyces cerevisiae results in the release of beta1,3-glucan into the medium and induces a compensation mechanism to ensure cell wall integrity

Deletion of GAS1/GGP1/CWH52 results in a lower beta-glucan content of the cell wall and swollen, more spherical cells (L. Popolo, M. Vai, E. Gatti, S. Porello, P. Bonfante, R. Balestrini, and L. Alberghina, J. Bacteriol. 175:1879-1885, 1993; A. F. J. Ram, S. S. C. Brekelmans, L. J. W. M. Oehlen, and F. M. Klis, FEBS Lett. 358:165-170, 1995). We show here that gas1delta cells release beta1,3-glucan into the medium. Western analysis of the medium proteins with beta1,3-glucan- and beta1,6-glucan-specific antibodies showed further that at least some of the released beta1,3-glucan was linked to protein as part of a beta1,3-glucan-beta1,6-glucan-protein complex. These data indicate that Gas1p might play a role in the retention of beta1,3-glucan and/or beta-glucosylated proteins. Interestingly, the defective incorporation of beta1,3-glucan in the cell wall was accompanied by an increase in chitin and mannan content in the cell wall, an enhanced expression of cell wall protein 1 (Cwp1p), and an increase in beta1,3-glucan synthase activity, probably caused by the induced expression of Fks2p. It is proposed that the cell wall weakening caused by the loss of Gas1p induces a set of compensatory reactions to ensure cell integrity.

Influence of centrifugation regimes on motility, yield, and cell associations of mouse spermatozoa

Mouse sperm are exceptionally sensitive to mechanical forces associated with pipetting and mixing. This characteristic raised the question of the sensitivity of mouse sperm to centrifugation, a step necessary in the removal of cryoprotectants and a common component in the general manipulation of sperm suspensions for experimental purpose. Epididymal spermatozoa from ICR mice were isolated and manipulated to minimize pipetting and mixing damage. The centrifugal accelerations studied were 200, 400, 600, and 800 x g (measured with a stroboscope) for 5, 10, or 15 minutes of centrifugation time. The number of cells and the number of motile cells were counted. The percent motility and longevity, total yield, and motile yield were calculated. Centrifugation at 200 and 400 x g for short times (5 minutes) caused only a small loss in either immediate or 2.5-hour motility, but centrifugation at 600 and 800 x g for 15 minutes produced up to a fivefold loss. Low speed/short time centrifugation pelleted only about half of the cells; the others were lost when the supernatant was removed. The maximum number of motile sperm (motile yield) was obtained at intermediate centrifugal forces (approximately 400 x g for 10-12 minutes), and it is the total number of motile sperm (and not the percent motility) that is important in the use of cryopreserved sperm to regenerate cryopreserved mutant lines. Relative centrifugal force and centrifugation time exhibit reciprocity (e.g., 200 x g for 10 minutes produces similar results to 400 x g for 5 minutes). The spermatozoa must be centrifuged under carefully defined conditions to minimize the damage and to maximize the recovery of viable cells.

Characterization of intraembryonic freezing in Anopheles gambiae embryos

Intraembryonic freezing (IEF) in Anopheles mosquito embryos has been evaluated by differential scanning calorimetry with respect to embryo age, temperature, rate and duration of cooling, and absence or presence of extraembryonic ice. The initial temperatures for intraembryonic ice nucleation were -30.1 +/- 0.3, -28.4 +/- 0.4, and -29.1 +/- 0.2 degree C for embryos incubated for 15 h at 17 degrees C, 15 h at 26 degrees C, and 24 h at 26 degrees C, respectively, after oviposition. The first value is slightly but significantly lower than the latter two. These values were obtained on embryos in which the surface water was removed by brief drying; however, the values were nearly identical when external water and ice were present. Not only were the embryos of all three ages able to supercool at least transiently to -26 degrees C, but they could remain supercooled for up to 4 h at -20 degrees C after being cooled to -20 degrees C at 10 degrees C/min or (in the case of embryos incubated for 15 h at 26 degrees C) at 100 degrees C/min. The amount of freezable water in single embryos has been calculated from the differential scanning calorimetry measurements to be 3.45 +/- 0.08, and 3.53 +/- 0.06 microgram for embryos incubated for 15 h at 17 degrees C, 15 h at 26 degrees C, and 24 h at 26 degrees C, respectively. The differences are not significant. The corresponding values for the total water contents for embryos of the three ages were 4.04 +/- 0.20, 3.72 +/- 0.16, and 3.98 +/- 0.10 microgram, values that also did not differ significantly. Water thus makes up approximately 74% of the total weight of the embryo (approximately 5.3 micrograms) and about 91% of that water is freezable. Total water contents were determined gravimetrically after extensive air and vacuum drying. The kinetics of dehydration were determined during the air drying. They differed substantially among the three ages. The embryos incubated for 15 h at 17 degrees C lost water at about four times the rate of those incubated for 15 h at 26 degrees C and 10 times the rate of the embryos incubated for 24 h at 26 degrees C.

Osmotic tolerance limits and properties of murine spermatozoa

Osmotic tolerance of spermatozoa is a critical determinant of functional survival after cryopreservation. This study first tested the hypothesis that mouse spermatozoa behave as linear osmometers, using an electronic particle counter to measure the change in sperm volume in response to anisosmotic solutions. The resulting Boyle-van't Hoff plot was linear (r2 = 0.99) from 75 to 1200 mOsmolal and indicates that 60.7% of the total cell volume is osmotically inactive. Next, mouse sperm tolerance to osmotic stress was determined by assessment of plasma membrane integrity, mitochondrial viability, and motility. Each functional endpoint was measured after exposure to anisosmotic solutions and again after return to isosmolality. The dual fluorescent stains-carboxyfluorescein diacetate with propidium iodide and Rhodamine 123 with propidium iodide-were used to determine membrane integrity and functional mitochondria, respectively. Motility was measured by video microscopy in the range of 1-2400 mOsmolal and was further analyzed from 140 to 600 mOsmolal using computer-assisted semen analysis. The data indicate that motility is substantially more sensitive to osmotic stress than either mitochondrial viability or membrane integrity and that mouse spermatozoa should be maintained within 76-124% of their isosmotic volume during cryopreservation in order to maintain > 80% of pretreatment motility.

In vitro activity of 1,3-beta-D-glucan synthase requires the GTP-binding protein Rho1

In the yeast Saccharomyces cerevisiae, the family of RHO genes are implicated in the control of morphogenetic events although the molecular targets of these GTP-binding proteins remain largely unknown. The activity of 1,3-beta-D-glucan synthase, the product of which is essential for cell wall integrity, is regulated by a GTP-binding protein, which we here present evidence to be Rho1p. Rho1p was found to copurify with Fks1p, a glucan synthase subunit, in preparations of the enzyme purified by product entrapment and was also shown to be depleted by a detergent extraction procedure known to remove the GTP-binding regulatory component. Specific ADP-ribosylation of Rho1p by exoenzyme C3 inactivates glucan synthase activity specified by FKS1 and FKS2 as demonstrated in membrane preparations from fks2 and fks1 deletion strains, respectively, and in the purified enzyme containing Fks1p. Rho1p and Fks1p were co-immunoprecipitated from purified glucan synthase under conditions that maintained enzyme activity in the immunoprecipitate. Putative Rho homologs were also identified and implicated in the regulation of glucan synthase activity from Candida albicans, Aspergillus nidulans, and Cryptococcus neoformans by ribosylation studies. The regulation of 1,3-beta-D-glucan synthase activity by RHO1 is consistent with its observed role in morphogenetic control and osmotic integrity.

Permeabilization of eggs of the malaria mosquito Anopheles gambiae

Although Anopheles gambiae embryos that have developed for 15 h at 17 degrees C are slightly permeable to water, they are impermeable to ethylene glycol, the cryoprotectant used in the cryopreservation of Drosophila melanogaster embryos. Success in cryopreservation requires that they be made permeable to protective solutes. Permeabilization of D. melanogaster was achieved by 1) dechorionation with 50% Clorox (household bleach) followed by 2) a water flush; 3) immersion in isopropyl alcohol to remove most extraembryonic water; 4) 2 min air drying to remove most isopropyl alcohol; 5) 90-s exposure to n-heptane containing 0.3% 1-butanol; and 6) 15-s exposure to pure n-heptane. The permeability of A. gambiae embryos was assessed by determining the times required for the initial dehydration of embryos in 1 M ethylene glycol in 260 mOsm Drosophila culture medium (permeability to water) and the times required for their return to normal volume (permeability to ethylene glycol). Based on these criteria, the above D. melanogaster procedure effectively permeabilizes 15 h/17 degrees C to 19 h/17 degrees C A. gambiae embryos. Nearly all collapsed in <5 min, and most returned to normal volume in approximately 40 min. Although permeable, all were killed by the permeabilization procedure. In analyzing the effect of each step on viability, 50% Clorox caused some lethality, and Clorox followed by isopropyl alcohol was 100% lethal. Decreasing the Clorox concentration to 10% still dechorionated eggs, but with reduced toxicity; substitution of a 10% solution of reagent-grade sodium hypochlorite for Clorox further decreased toxicity. The isopropyl alcohol step was also toxic. Consequently, the removal of residual surface water was achieved by substituting air drying for isopropyl alcohol. The drying took place under direct microscope observation and was continued until the embryos began to shrink. The combination of this modified method for dechorionation and controlled air drying before exposure to heptane resulted in permeabilization of all embryos in most runs and in approximately 30% survival of the permeabilized embryos.

Permeability of intact and dechorionated eggs of the Anopheles mosquito to water vapor and liquid water: a comparison with Drosophila

As an initial step in the development of cryopreservation methods for Anopheles gambiae embryos, we determined the permeability of intact and dechorionated A. gambiae embryos to water and ethylene glycol and compared those permeabilities with those of Drosophila melanogaster embryos. Most studies were conducted on embryos allowed to develop for 8 h at 26 degrees C or 15 h at 17 degrees C. Intact A. gambiae embryos are some 50 times more permeable to water vapor than are D. melanogaster embryos; e.g., when air dried, half of 15 h/17 degrees C A. gambiae embryos become severely dehydrated in 3. 5-4.0 min, whereas comparably aged D. melanogaster embryos require approximately 4 h or more. Comparable differences between the two species exist with respect to the loss of liquid water under an osmotic driving force. After 90 min in 0.75 M sucrose in 0.26 osmolal D-20 Drosophila medium, 25-40% of intact A. gambiae embryos underwent extensive shrinkage, whereas D. melanogaster embryos showed no shrinkage. The chorion of both species can be removed by a 2.5-min exposure to 50% household bleach (Clorox). Dechorionation increases the rate of water loss two- to sixfold during air drying in both species and during exposure to hyperosmotic sucrose in A. gambiae. Dechorionated D. melanogaster embryos, however, show no shrinkage in hyperosmotic sucrose even after 6 h. The water permeability of dechorionated A. gambiae embryos thus remains many-fold higher than that of dechorionated D. melanogaster embryos. Although moderately permeable to water, neither intact nor dechorionated A. gambiae embryos are permeable to ethylene glycol, as evidenced by the failure of dehydrated embryos to reexpand in 120-180 min in that solution.

Crystallization and preliminary crystallographic analysis of 3-carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa

Crystals of 3-carboxy-cis,cis-muconate lactonizing enzyme (CMLE; E.C. 5.5.1.5) from Neurospora crassa that diffract to high resolution have been obtained. The crystals belong to the orthorhombic space group P2(1)2(1)2(1) with unit-cell dimensions a = 92.1, b = 159.7, c = 236.6 A (at 103 K) and diffract at most to 2 A resolution. The asymmetric unit of the crystals appears to contain two tetrameric CMLE molecules making up a total of 328 kDa per asymmetric unit. Both cross-linking with glutaraldehyde and cryo-cooling to 103 K have been used to facilitate data collection because the crystals are unstable in the X-ray beam; both techniques extend the crystal lifetime but cryo-cooling, unlike glutaraldehyde cross-linking, does not lower the quality of the diffraction pattern.