Coexistence of Multiple Gene Variants in Some Patients with Erythrocytoses

Background

Erythrocytosis is a relatively common condition; however, a large proportion of these patients (70%) remain without a clear etiologic explanation.

Methods

We set up a targeted NGS panel for patients with erythrocytosis, and 118 sporadic patients with idiopathic erythrocytosis were studied.

Results

In 40 (34%) patients, no variant was found, while in 78 (66%), we identified at least one germinal variant; 55 patients (70.5%) had 1 altered gene, 18 (23%) had 2 alterations, and 5 (6.4%) had 3. An altered HFE gene was observed in 51 cases (57.1%), EGLN1 in 18 (22.6%) and EPAS1, EPOR, JAK2, and TFR2 variants in 7.7%, 10.3%, 11.5%, and 14.1% patients, respectively. In 23 patients (19.45%), more than 1 putative variant was found in multiple genes.

Conclusions

Genetic variants in patients with erythrocytosis were detected in about 2/3 of our cohort. An NGS panel including more candidate genes should reduce the number of cases diagnosed as "idiopathic" erythrocytosis in which a cause cannot yet be identified. It is known that HFE variants are common in idiopathic erythrocytosis. TFR2 alterations support the existence of a relationship between genes involved in iron metabolism and impaired erythropoiesis. Some novel multiple variants were identified. Erythrocytosis appears to be often multigenic.

Prevalence and Causes of Anemia in Hospitalized Patients: Impact on Diseases Outcome

Anemia is extremely common in hospitalized patients who are old and often with multiple diseases. We evaluated 435 consecutive patients admitted in the internal medicine department of a hub hospital and 191 (43.9%) of them were anemic. Demographic, historic and clinical data, laboratory tests, duration of hospitalization, re-admission at 30 days and death were recorded. Patients were stratified by age (<65, 65-80, >80 years), anemia severity, and etiology of anemia. The causes of anemia were: iron deficiency in 28 patients, vitamin B12 and folic acid deficiencies in 6, chronic inflammatory diseases in 80, chronic kidney disease in 15, and multifactorial in 62. The severity of the clinical picture at admission was significantly worse (p < 0.001), length of hospitalization was longer (p < 0.001) and inversely correlated to the Hb concentration, re-admissions and deaths were more frequent (p 0.017) in anemic compared to non-anemic patients. A specific treatment for anemia was used in 99 patients (36.6%) (transfusions, erythropoietin, iron, vitamin B12 and/or folic acid). Anemia (and/or its treatment) was red in the discharge letter only 54 patients. Even if anemia is common, in internal medicine departments scarce attention is paid to it, as it is generally considered a "minor" problem, particularly in older patients often affected by multiple pathologies. Our data indicate the need of renewed medical attention to anemia, as it may positively affect the outcome of several concurrent medical conditions and the multidimensional loss of function in older hospitalized patients.

Thrombotic Events in Homozygotes with a Proven or Highly Probable Arg304Gln Factor VII Mutation (FVII Padua)1): Only Limited Replacement Therapy is Needed in Case of Surgery

OBJECTIVE

To investigate the prevalence of thrombotic events among patients with proven or highly probable homozygosis for the Arg304Gln (Factor VII Padua) defect or compound heterozygosis containing the Arg304Gln mutation.

METHODS

Homozygotes and compound heterozygotes proven by molecular studies to have the Arg304Gln mutation were gathered from personal files and from two PubMed searches. In addition, patients with probable homozygosis on the basis of clotting tests (discrepancies among Factor VII activity levels according to the tissue thromboplastin used) were also gathered.

RESULTS

30 proven homozygotes and 17 probable ones were gathered together with 8 compound heterozygotes. In the latter use, the associated mutation was Cys135Arg (twice), Gly180Arg, Arg304Trp, Arg315Trp, His348Gln, Gly365Cys. The prevalence of venous thrombotic events was 16.6, 11.8 and 11.1 percent, respectively for the three groups of patients. Heterozygotes showed no thrombotic event. The difference for proven homozygotes was statistically significant, while for the other groups only a trend was present.

CONCLUSION

proven homozygous or compound heterozygous patients with the Arg304Gln mutation showed a higher than expected incidence of thrombotic events. The same is true for probable cases gathered only on the basis of clotting tests. These patients, because of their frequent lack of bleeding and for their relatively high prevalence of thrombosis should probably receive only limited replacement therapy in case of surgical procedures.

Correction to: New clotting disorders that cast new light on blood coagulation and may play a role in clinical practice

The original version of the article unfortunately contained few errors.

Vitamin K-Dependent Coagulation Factors That May be Responsible for Both Bleeding and Thrombosis (FII, FVII, and FIX)

Vitamin K-dependent clotting factors are commonly divided into prohemorrhagic (FII, FVII, FIX, and FX) and antithrombotic (protein C and protein S). Furthermore, another protein (protein Z) does not seem strictly correlated with blood clotting. As a consequence of this assumption, vitamin K-dependent defects were considered as hemorrhagic or thrombotic disorders. Recent clinical observations, and especially, recent advances in molecular biology investigations, have demonstrated that this was incorrect. In 2009, it was demonstrated that the mutation Arg338Leu in exon 8 of FIX was associated with the appearance of a thrombophilic state and venous thrombosis. The defect was characterized by a 10-fold increased activity in FIX activity, while FIX antigen was only slightly increased (FIX Padua). On the other hand, it was noted on clinical grounds that the thrombosis, mainly venous, was present in about 2% to 3% of patients with FVII deficiency. It was subsequently demonstrated that 2 mutations in FVII, namely, Arg304Gln and Ala294Val, were particularly affected. Both these mutations are type 2 defects, namely, they show low activity but normal or near-normal FVII antigen. More recently, in 2011-2012, it was noted that prothrombin defects due to mutations of Arg596 to Leu, Gln, or Trp in exon 15 cause the appearance of a dysprothrombinemia that shows no bleeding tendency but instead a prothrombotic state with venous thrombosis. On the contrary, no abnormality of protein C or protein S has been shown to be associated with bleeding rather than with thrombosis. These studies have considerably widened the spectrum and significance of blood coagulation studies.

Heparin, coumarin, protein C, antithrombin, fibrinolysis and other clotting related resistances: old and new concepts in blood coagulation

The concept of resistance in blood coagulation has become important. In the past it was limited to the resistance shown by some patients to heparin, coumarin or aspirin. Subsequently, it was demonstrated that a mutation in a single clotting factor, FV, showed resistance to activated protein C. Since activated protein C is supposed to downregulate aFV and aFVIII, their persistence in the circulation gives origin to a hypercoagulable state. Recently antithrombin resistance has been defined. Several prothrombin abnormalities (dysprothrombinemias) have been shown to be resistant to the action of antithrombin. This is associated with the occurrence of a trombophilic state. Prothrombin may therefore be associated like FV with both a bleeding condition (prothrombin deficiency) and a thrombophilic state (some dysprothrombinemias). Finally, thrombomodulin resistance has been defined in liver cirrhosis. These patients often show an increased ratio between FVIII levels and protein C. This imbalance may be partly responsible for the frequent presence of portal vein thrombosis seen in these patients. All these studies have greatly increased the complexity of the clotting mechanisms and interactions. They have cast light on clinical events which had remained unknown or ill-defined.

Prothrombin: Another Clotting Factor After FV That Is Involved Both in Bleeding and Thrombosis

Clotting factor defects are usually associated with bleeding. About 2 decades ago, 2 polymorphisms, one of FII (G20210A) and another of FV (Arg506Gln), have been shown to be associated with prothrombotic state and venous thrombosis. As a consequence, FII and FV could be considered both as prohemorrhagic factors and prothrombotic conditions. Recently, it has been shown that missense mutations in the prothrombin gene of amino acid Arg596 of exon 14 to Leu596, Gln596, or Trp596 caused the appearance of a thrombophilic state and venous thrombosis. These mutated FII are not associated with bleeding, but only with venous thrombosis. Furthermore, they are all heterozygotes for the mutations. No missense mutation associated with thrombosis has been discovered so far for FV. As a consequence, the prothrombotic activity of FII is the result of a polymorphism and of a missense mutation, whereas that of FV derives only from a polymorphism. The observation that a clotting factor defect may be associated with both bleeding or venous thrombosis depending on the site of the mutation has caused an extensive reevaluation of the blood clotting mechanism.

Effects of Embryonic Development Stage and Cryoprotective Agents on Galleria Mellonella Embryo Cryopreservation

BACKGROUND

The increased research use of the honeycomb pest Galleria mellonella has created the need for cryopreservation. The diverse characteristics of G. mellonella embryos at different stages may affect embryo survival upon cryopreservation due to differential dehydration, cold resistance, cryoprotectant toxicity and permeability.

OBJECTIVE

The study aimed to determine the ability of G. mellonella to survive cryogenic condition in the early and late embryonic developmental stages (24h and 75h post-oviposition, PO).

MATERIALS AND METHODS

A modified protocol was used to select the proper embryonic stage by comparing the early and late embryonic stages under two procedures of dechorionation-permeabilization (D/P) dilutions. The embryos at the early stage were used for testing the toxicity and viscosity effects of various cryoprotective agents. Various cryoprotectant treatments for improving the hatch rate were studied.

RESULTS

The survival rates of embryos at the early stages (24h PO) were 51.5% and 69.5% respectively after cryoprotectant loading in 12% ethylene glycol (EG) for 30 min and dehydration in vitrification solution for for 10min. These survival rates of embryos at the late stages (75h PO), however, decreased to 22.9% and 34.0%, respectively. D/P treatment with Tween 20 and Tween 80 (2:6) slightly improved the survival of embryos at the 24h PO stage after immersion in liquid nitrogen (LN) from 0.1% to 0.6%. The increased exposure time in dehydration treatment from 14 to 30min in two vitrification solutions, EG and methanol (MeOH), slightly increased the survival rate of cryopreserved embryos from 0% and 0.3% to 1.1% and 1.4%, respectively, while the vitrification solution containing dimethyl sulfoxide (Me2SO or DMSO) slightly decreased the hatch rate from 1% to 0.6%.

CONCLUSION

The survival rate of G. mellonella embryos after cryopreservation was affected by the oviposition period, eggshell permeability to cryoprotectant, cryoprotectant type, as well as their concentration and exposure times.

Factor X Friuli Coagulation Disorder: Almost 50 Years Later

The story of factor X (FX) Friuli. Factor X Friuli was discovered in 1969 to 1970. However, the story of that disease was an international event since patients with this defect were studied in France and in Italy, and different diagnoses were reached-FVII; FX; combined prothrombin complex; and combined FII, FVII, and FX deficiencies. The diagnostic difficulties were due to the peculiar clotting pattern presented by these patients, namely, prolonged partial thromboplastin time, prolonged prothrombin time but normal Russell viper venom clotting time. Only suitable anti-FX antisera clarified the pattern. Altogether 12 homozygotes and 102 heterozygotes have been followed during 4 decades. Six homozygotes died, 2 of them due to HIV infection and 1 due to hepatitis B liver cirrhosis. The other 3 died of nontransfusion-related morbidity. Bleeding tendency has been moderate in agreement with the extrinsic or intrinsic system assay results-FX level of 4% to 5% is considered normal. Heterozygotes may present occasional bleeding manifestations usually during surgery or delivery. Molecular analysis have shown that the mutation responsible for the defect is a Pro343Ser substitution in exon 8. Chimeric FX Friuli mice have been useful in studying the effect of FX levels on embryonic or natal mortality of these animals. No new homozygote but several heterozygotes have been recently seen. The study of FX Friuli has revolutionized the diagnostic approach to FX deficiencies. The FX should be assayed by all assay systems. The FX Friuli has never been described in any other country, and all patients studied come from the Friuli Meduna River Valley.

Thrombotic and Hemorrhagic Conditions Due to a Gain of Function of Coagulation Proteins: A Special Type of Clotting Disorders

Coagulation disorders can be classified into 2 types, namely, type I and type II. In the former, there is a concomitant decrease in factor activity and antigen (activity-antigen ratio is 1), whereas in the latter, there is a discrepancy between factor activity which is always low and antigen which is normal or near normal (activity-antigen ratio is <1, eg, 0.5). Recently, several gain-of-function disorders have been described. These are characterized by an increased activity with respect to the antigen level. The condition involves polymorphisms of factor V and factor II, factor IX, von Willebrand disease, thrombomodulin, tissue factor pathway inhibitor, and thrombin activatable fibrinolysis inhibitor. The conditions could be subdivided into prothrombotic and prohemorrhagic. They should also be distinguished as cases of true gain of function (intrinsic increase activity without concomitant increase in protein level) and of "pseudo" gain of function (increase in both activity and protein level). This is a new concept of coagulation defects that has considerably enhanced our knowledge of blood coagulation and that should be familiar to all those interested in the mechanism of blood clotting and its disorders.

Bleeding manifestations in heterozygotes with congenital FVII deficiency: a comparison with unaffected family members during a long observation period

OBJECTIVES

To determine whether heterozygotes with FVII deficiency have a bleeding tendency or not.

PATIENTS AND METHODS

Eighty-four patients (OK) heterozygous for FVII deficiency, at the onset of the study, were paired with unaffected family members and followed for a long period of time (mean 22.6 years) for the occurrence of bleeding. Diagnosis of heterozygosis had to be based on family studies, clotting, immunological assays and genetic analysis.

RESULTS

The mean FVII activity level was 0.51 IU/dl (range 35-65) and 94 IU/dl (range 88-118) in the heterozygotes and in the normal counterparts, respectively. Documented bleeding manifestations occurred in eight heterozygotes and in seven normal subjects. Statistical analysis of the difference was not significant. Bleeding manifestations were easy bruising, bleeding after tooth extractions, menorrhagia, epistaxis with no difference among the two groups. There was no strict correlation between bleeding and FVII activity levels.

CONCLUSIONS

The study indicates that heterozygotes for FVII deficiency show rare bleeding manifestations which are also present in the unaffected family members with normal FVII levels. This indicates that Factor VII activity levels played no role in the occurrence of the bleeding symptoms. Furthermore, FVII levels of around 0.40 IU/dl are capable of assuring a normal hemostasis.

Thrombotic risk correlates with mutational status in true essential thrombocythemia

BACKGROUND

True essential thrombocythemia (ET) may carry one of the known driver mutations (JAK2, MPL and CALR) or none of them [in triple-negative (3NEG) cases]. The patients' mutational status seems to delineate the clinical manifestations of ET.

MATERIALS AND METHODS

We report the data of 183 patients diagnosed with ET strictly according to the WHO 2008 criteria and with a full molecular diagnosis, including the following: 114 patients (62·3%) with JAK2V617F; 25 (13·7%) with CALR type 1 and 19 (10·4%) with CALR type 2; 3 (1·6%) with MPL; 22 (12%) who were 3NEG. Thrombotic risk was assessed by means of the IPSET-thrombosis score (IPSET-T).

RESULTS

CALR and 3NEG patients had lower haemoglobin levels and leucocyte count than JAK2 patients. CALR patients, and those with type 2 in particular, had higher mean platelet counts and had extreme thrombocytosis more often than any of the other groups. Based on their IPSET-T stratification, 3NEG- and CALR-mutated patients belonged more frequently to the low-risk group and had a significant more favourable thrombosis-free survival rate than those with JAK2 mutation.

CONCLUSION

These findings indicate that the three different molecular markers have a significant impact on the clinical course of true ET, giving rise to different phenotypes of the same disease.

Acquired Isolated FVII Deficiency

Objective:

To investigate all cases of isolated factor VII (FVII) deficiency as gathered from personal files or by a PubMed search.

Patients and Methods:

Personal files dealing with patients studied in Padua during the years 1970 to 2010 were reevaluated. The PubMed search was time unlimited and was carried on 2 occasions during 2014. Cross-checking of the references, listed in every article, was also carried out to avoid omissions. Inclusion criteria were isolated FVII defect of less than 40% of normal, negative coagulation pattern in the family, normal level of other vitamin K-dependent clotting factors, and normalization of the clotting factor after the therapeutic procedures, unless the patient died.

Results:

Twenty-nine patients met the inclusion criteria (18 male and 9 female, in 2 cases gender was unreported). This number included 1 personal case. Mean age was 37.9 (range 3-80). Underlying diseases were the following: neoplasia, infections, polytrauma, penicillin administration, nephrotic syndrome Wiskott Aldrich syndrome, and left heart failure (1 case, each); 2 patients had no underlying disease. Bleeding was variable but usually mild. There were 11 fatalities.

Conclusions:

Isolated FVII deficiency is a rare defect, which appears to be a finding associated with several morbid conditions, especially sepsis and tumors. This indicates the need for a careful investigation of even a mild prolongation of prothrombin time, especially when fibrinogen and partial thromboplastin time are normal.

Thrombotic Events in Asymptomatic FXII Deficiency versus Symptomatic FXI Deficiency: Surprising Observations

OBJECTIVE

To evaluate the impact of an asymptomatic congenital clotting defect (FXII deficiency) versus that of a similar but symptomatic defect (FXI deficiency) on protection from thrombosis.

PATIENTS AND METHODS

All patients with FXII or FXI deficiency and thrombosis were gathered from a time-unlimited PubMed search that was carried out twice and from personal records. Combined defects were excluded. The defect had to be proven by the demonstration of a suited hereditary pattern and by a specific clotting assay. Only patients with a factor activity level of <30% of normal were selected.

RESULTS

Twenty-eight patients with an FXII deficiency presented with arterial thrombosis, mainly myocardial infarction, and 29 showed venous thrombosis; for FXI deficiency, these figures were 43 and 10, respectively. The ratio of arterial and venous thrombosis was 0.96 and 4.3, respectively, for FXII and FXI deficiency.

CONCLUSIONS

Factor FXII deficiency supplies no protection from arterial or venous thrombosis. FXI deficiency shows no protection from arterial thrombosis but appears to guarantee protection from venous thrombosis. A symptomatic, namely bleeding, condition (FXI deficiency) provides protection from venous thrombosis whereas an asymptomatic one (FXII deficiency) does not.

Drug-Induced Thrombophilic or Prothrombotic States: An Underestimated Clinical Problem That Involves Both Legal and Illegal Compounds

Vascular thrombosis, both arterial and venous, is a condition associated with significant morbidity and mortality. There are multiple risk factors for thrombosis, both congenital and acquired, and in the majority of cases, these risk factors are not modifiable. Over the past 2 decades, multiple drugs (both illegal and legal) have been associated with increased risk of thrombosis. However, due to limited scientific literature regarding the prothrombotic tendencies of these drugs, there is a concomitant limited understanding of the pathophysiology of drug-induced thrombosis. As drugs are one of the few modifiable risk factors for thrombosis, further study and dissemination of knowledge regarding drug-associated and drug-induced thrombosis are essential and have the potential to lead to decreased future incidence of thrombosis. The mechanisms at the basis of the thrombophilic activity of these drugs are variable and sometimes still ill recognized. Increased levels of clotting factors, reduction in coagulation natural inhibitors, decreased fibrinolysis, activated clotting factors, increased blood viscosity, endothelial damage, and increased platelet number and activation are the most frequent causes. Arterial steal or coronary arteries no flow has also been implicated. In some cases due to the intake of several drugs, more than one mechanism is present in a given patient. The purpose of the present review is to analyze all the drugs demonstrated to be potentially thrombotic. It is hoped that a prudent use or nonuse of these drugs might result in a reduction of thrombosis-associated diseases.

The Story of Serum Prothrombin Conversion Accelerator, Proconvertin, Stable Factor, Cothromboplastin, Prothrombin Accelerator or Autoprothrombin I, and Their Subsequent Merging into Factor VII

Factor VII (FVII) deficiency is one of the two congenital coagulation disorders that was not discovered by the description of a new bleeding patient whose clotting pattern did not fit the blood coagulation knowledge of the time (the other is factor XIII deficiency). The existence of an additional factor capable of accelerating the conversion of prothrombin into thrombin was suspected before 1951, the year in which the first family with FVII deficiency was discovered. As several investigators were involved in the discovery of FVII deficiency from both sides of the Atlantic, several different names were tentatively suggested to define this entity, namely stable factor (in contrast with labile factor or FV), cothromboplastin, proconvertin, serum prothrombin conversion accelerator, prothrombin acceleration, and autoprothrombin I. The last term was proposed by those who denied the existence of this new entity, which was instead considered to be a derivate of prothrombin activation, namely autoprothrombin. The description of several families, from all over the world, of the same defect, however clearly demonstrated the singularity of the condition. Factor VII was then proposed to define this protein. In subsequent years, several variants were described with peculiar reactivity toward tissue thromboplastins of different origin. Molecular biology techniques demonstrated several gene mutations, usually missense mutations, often involving exon 8 of the FVII gene. Later studies dealt with the relation of FVII with tissue factor and activated FVII (FVIIa). The evaluation of circulating FVIIa was made possible by the use of a truncated form of tissue factor, which is only sensitive to FVIIa present in the circulation. The development of FVII concentrates, both plasma derived and recombinant, has facilitated therapeutic management of FVII-deficient patients. The use of FVIIa concentrates was noted to be associated with the occasional occurrence of thrombotic events, mainly venous. Total or partial liver transplants have been performed with success in these patients and have "cured" their deficiencies. Prenatal diagnosis has also been performed and recent research involves the development of inhibitors of FVII + tissue factor complex or of FVIIa. This approach, if successful, could provide another antithrombotic therapeutics tool. The story of FVII well summarizes the efforts of both theoretical and clinical approaches in the characterization of a coagulation disorder, that is, among the rare bleeding conditions, most frequently encountered in clinical practice.

Complex history of the discovery and characterization of congenital factor X deficiency

Factor X (FX) plays a pivotal role in blood coagulation. FX represents the point where all coagulation systems converge and, once activated, it converts prothrombin into thrombin. The discovery and definition of FX are based on the description between 1956 and 1957 about three patients and their families with a peculiar defect later demonstrated to be almost identical. These patients were an American (Mr. Stuart), a British (Ms. Prower), and a Swiss with Italian background (infant Delia B). We stated "almost identical" because immunological and molecular biology studies subsequently revealed that even though the basic clotting defect was identical, the FX protein level and the mutation were different in each case. Mr. Stuart had no FX protein in his plasma and the mutation was Val298Met (homozygote). Ms. Prower instead had a normal level of FX protein and the mutation was Arg287Trp + Asp282Asn (compound heterozygote). Unfortunately, the status of the Swiss patient in this regard is not known. Subsequent studies described a few major variants (FX Friuli, FX Melbourne, FX Padua, and other similar patients), which showed peculiar activation patterns (FX Friuli had a normal Russell viper venom clotting time; FX Melbourne was defective only in the intrinsic coagulation system; FX Padua, on the contrary, was defective only in the extrinsic coagulation system). All these studies have informed on the great heterogeneity and complexity of the FX defect. The story of the discovery and classification of FX deficiency has contributed considerably to our understanding of blood coagulation. The three original families and the families of the major variants, together with the researchers that discovered them, should be remembered with deep respect and gratitude.

Myocardial Infarctions and Other Acute Coronary Syndromes in Rare Congenital Bleeding Disorders

Objective:

To investigate the occurrence of myocardial infarction or other acute coronary syndromes in rare congenital bleeding disorders.

Patients:

All patients with factor I (FI), factor II (FII), factor V (FV), factor VII (FVII), factor X (FX), factor XI (FXI), or factor XIII (FXIII) deficiency or abnormality reported to have presented a myocardial infarction or another acute coronary syndrome were investigated. The condition had to be demonstrated by objective means, including a coronary/angiography. Cases of stable angina were excluded.

Results:

A total of 53 patients (4 had FI, 2 had FV, 2 had FVII, 36 had FXI, 1 had FXIII deficiency, and 8 patients had platelet disorders) met the inclusion criteria . No patient with FII or FX deficiency and acute coronary disease met the inclusion criteria. In the majority of patients, common risk factors were present, namely hypertension, hypercholesterolemia, smoking, and diabetes. Replacement therapy was involved in 5 cases.

Conclusion:

The congenital hypocoagulability present in these patients was unable to allow a protection from acute coronary diseases. The significance of the findings is discussed.

The effect of Tween 80 on eggshell permeabilization in Galleria mellonella (L.) (Lepidoptera, Pyralidae)

The development of a species-specific protocol for dechorionation and permeabilization of insect eggs is a necessary prerequisite to cryopreserve the embryos. Here we tested different procedures based on heptane or the surfactant Tween 80 as an alternative to alkane, evaluating their efficacy and toxicity on the early (24 h post-oviposition) and late (75 h post-oviposition) stage embryos. Heptane efficiently permeabilized the eggs of G. mellonella but the hatching rate ranged from 0.1 to 4.2 percent in the early stage and from 4.3 to 11.2 percent in the late stage. The embryos treated with 1.25 percent NaOCl + 0.08 percent Tween 80 for 2 min showed the same shrinkage and reswelling percentages as eggs exposed to heptane for 10 sec, with a significantly higher hatching percentage in the early (68.2 +/- 1.5 percent) and late stages (22.4 +/- 3.7 percent). Thus, 0.08 percent Tween 80 allows sufficient permeabilization of G. mellonella embryos without the high toxicity of alkane.

Lipids and NADPH-dependent superoxide production in plasma membrane vesicles from roots of wheat grown under copper deficiency or excess

The effects of in vivo copper on the lipid composition of root plasma membrane and the activities of membrane-bound enzymes, such as NADPH-dependent oxidases and lipoxygenase, were studied. Plants were grown in hydroponic culture for 11 d without Cu supply or in the presence of 50 microM Cu. Control plants were supplied with 0.3 microM Cu. Growth of roots was severely affected in the 50 microM Cu-grown plants, whereas roots grown in Cu-deficient solution did not show any difference in comparison with the control. The 50 microM Cu concentration caused an increase in the leakage of K(+) ions as well. Excess metal supply resulted in a decrease in the total lipid content of plasma membrane, a higher phospholipid amount and a reduction of steryl lipids (free sterols, steryl glycosides and acylated steryl glycosides). Cu depletion in the growth solution had only a slight effect on the plasma membrane lipid composition. In comparison with the control, only the excess of Cu caused a decrease in the lipid to protein ratio as well as a change in the phospholipid composition, with a lower phosphatidylcholine to phosphatidylethanolamine ratio. The degree of unsaturation of root plasma membranes decreased following the 0 Cu treatment and even more after the 50 microM Cu supply. Plasma membranes of wheat grown under metal deficiency and excess showed increased NADPH-dependent superoxide-producing oxidase activities, whereas membrane-bound lipoxygenase was not increased or activated due to Cu treatments. The consequences of changes in plasma membrane lipid composition and activated oxygen production as a result of Cu treatments are discussed.