Presentation of Meibomian Acini Compared to Dermal Papillae of the Eyelid Margin, Using Confocal Laser Scanning Microscopy and Corresponding Histology.

BACKGROUND: Numerous studies have investigated the eyelid margin using confocal laser scanning microscopy (CLSM) and have presented morphological alterations of the examined structures, which were presumed to be Meibomian acini. However, recent data confirm that these structures are the cross-sections of dermal papillae of the dermoepidermal junction. This study aims to present the morphological appearance of Meibomian acini examined by confocal laser scanning microscopy in comparison to dermal papillae, and to reveal the corresponding patterns with specific histological sections. METHODS AND MATERIAL: Twenty healthy patients were examined with a CLSM device in vivo at the marginal edge of the eyelid. Twenty-two samples of full-thickness eyelid wedges from 22 patients treated surgically with ectropion were collected, of which 11 freshly excised samples were imaged on the incision surface with CLSM ex vivo and 11 eyelids underwent conventional histological preparation. The represented structures on CLSM images were compared to Meibomian acini on histological sections in terms of area, longest and shortest diameter, as well as depth and density. RESULTS: On in vivo CLSM images, Meibomian orifices, epidermal cells, and dermal connective tissue could be identified, the latter in a cross-sectional view of the dermal papillae surrounded by basal cells of the epidermis, forming reflective ring-like structures. All morphological parameters of these structures differed from Meibomian acini measured on histological sections. In contrast, the CLSM images of the incision surface showed acinar units with the same morphology as the Meibomian acini seen in the histological images and no statistically significant difference was found between the corresponding parameters. CONCLUSION: The morphological appearance of Meibomian acini differs from the structures that were previously presumed as Meibomian glands on CLSM images. In vivo imaging of Meibomian glands by commonly used in vivo CLSM cannot be performed.

Biological properties of influenza A virus mutants with amino acid substitutions in the HA2 glycoprotein of the HA1/HA2 interaction region.

Influenza A viruses (IAVs) enter into cells by receptor-dependent endocytosis. Subsequently, conformational changes of haemagglutinin are triggered by low environmental pH and the N terminus of HA2 glycoprotein (gp) is inserted into the endosomal membrane, resulting in fusion pore formation and genomic vRNA release into the cytoplasm. However, the pH optimum of membrane fusion is host- and virus-specific and can have an impact on virus pathogenicity. We prepared mutants of neurotropic IAV A/WSN/33 (H1N1) with aa substitutions in HA2 gp at the site of HA1/HA2 interaction, namely T642H (HA2 numbering position 64, H1 numbering position HA407; referred to as mutant '64'), V662H ('66') (HA409); and a double mutant ('D') with two aa substitutions (T642H, V662H). These substitutions were hypothesized to influence the pH optimum of fusion. The pH optimum of fusion activity was measured by a luciferase assay and biological properties of viruses were monitored. The in vitro and in vivo replication ability and pathogenicity of mutants were comparable (64) or lower (66, D) than those of the wild-type virus. However, the HA2 mutation V662H and double mutation T642H, V662H shifted the fusion pH maximum to lower values (ranging from 5.1 to 5.3) compared to pH from 5.4 to 5.6 for the wild-type and 64 mutant. The decreased replication ability and pathogenicity of 66 and D mutants was accompanied by higher titres in late intervals post-infection in lungs, and viral RNA in brains compared to wild-type virus-infected mice. These results have implications for understanding the pathogenicity of influenza viruses.

Single-cell studies of IFN-ß promoter activation by wild-type and NS1-defective influenza A viruses.

Deletion or truncation of NS1, the principal IFN antagonist of influenza viruses, leads to increased IFN induction during influenza virus infection. We have studied activation of the IFN induction cascade by both wild-type and NS1-defective viruses at the single-cell level using a cell line expressing GFP under the control of the IFN-ß promoter and by examining MxA expression. The IFN-ß promoter was not activated in all infected cells even during NS1-defective virus infections. Loss of NS1 expression is therefore insufficient per se to induce IFN in an infected cell, and factors besides NS1 expression status must dictate whether the IFN response is activated. The IFN response was efficiently stimulated in these cells following infection with other viruses; the differential IFN response we observe with influenza viruses is therefore not cell specific but is likely due to differences in the nature of the infecting virus particles and their subsequent replication.

The highly conserved, N-terminal (RXXX)8 motif of mouse Shadoo mediates nuclear accumulation.

The prion protein (PrP)-known for its central role in transmissible spongiform encephalopathies-has been reported to possess two nuclear localization signals and localize in the nuclei of certain cells in various forms. Although these data are superficially contradictory, it is apparent that nuclear forms of the prion protein can be found in cells in either the healthy or the diseased state. Here we report that Shadoo (Sho)-a member of the prion protein superfamily-is also found in the nucleus of several neural and non-neural cell lines as visualized by using an YFP-Sho construct. This nuclear localization is mediated by the (25-61) fragment of mouse Sho encompassing an (RXXX)8 motif. Bioinformatic analysis shows that the (RXXX)n motif (n=7-8) is a highly conserved and characteristic part of mammalian Shadoo proteins. Experiments to assess if Sho enters the nucleus by facilitated transport gave no decisive results: the inhibition of active processes that require energy in the cell, abolishes nuclear but not nucleolar accumulation. However, the (RXXX)8 motif is not able to mediate the nuclear transport of large fusion constructs exceeding the size limit of the nuclear pore for passive entry. Tracing the journey of various forms of Sho from translation to the nucleus and discerning the potential nuclear function of PrP and Sho requires further studies.

The RNA polymerase of influenza a virus: mechanisms of viral transcription and replication.

The influenza A virus RNA genome segments are packaged in ribonucleoprotein complexes containing RNA polymerase and nucleoprotein. The ribonucleoprotein is involved in the transcription of viral genes and replication of the viral RNA genome in the nucleus of the infected cells, and represents the minimal transcriptional and replicative machinery of an influenza virus. During transcription, the viral RNA polymerase synthesizes capped and polyadenylated mRNA using 5΄ capped RNA primers. During replication, the viral RNA polymerase generates a complementary RNA (cRNA) replication intermediate, a full-length complement of the vRNA that serves as a template for the synthesis of new copies of vRNA. The nucleoprotein is also an essential component of the viral transcriptional machinery. The molecular determinants of the transcriptional and replicative activities of the viral RNA polymerase are not fully understood, but recent data suggest that transcription is performed by a cis-acting RNA polymerase, forming part of the ribonucleoprotein complex, while replication might be carried out by a trans-acting RNA polymerase. Viral as well as cellular factors are known to be involved in the regulation of the activities of the RNA polymerase, e.g. the viral nuclear export protein has been shown to regulate the accumulation of viral transcription and replication products. The viral transcriptional machinery represents an attractive target for the development of antiviral drugs and lead compounds targeting nucleoprotein and the PA endonuclease domain of the RNA polymerase have already been identified.

GITR-expressing regulatory T-cell subsets are increased in tumor-positive lymph nodes from advanced breast cancer patients as compared to tumor-negative lymph nodes.

Lymph node (LN) infiltration by neoplastic process involves important changes in lymph node immune microenvironment. In particular, regulatory T cells (Treg) seem to have a key role in altering the immunoediting function of the immune system which leads to the elusion of the tumor from immune surveillance. In this study, we evaluated the expression of T-cell markers in CD4+ and CD8+ subsets from tumor-positive and tumor-negative lymph nodes from the same, advanced stage breast cancer patient. The study was carried out on 3 patients and similar results were obtained. Flow cytometric analysis of CD8+ cells demonstrated a significant difference in the expression of CD25, CD45RA, CD45RO, and GITRL (Glucocorticoid-Induced TNF receptor-Related ligand). Flowcytometric analysis of CD4+ cells demonstrated a significant difference in the expression of GITR (Glucocorticoid-Induced TNF receptor-Related), CD25, FoxP3 (Forkhead box P3), CD28, and CD45RA. Multiple staining allowed the identification of two Treg subpopulations, CD4+ CD25 highGITR+ CD127-/low and CD4+ CD25 low GITR+ CD127+ cells, proving that both are increased in the positive nodes in comparison with the negative nodes from the same patient. We identified for the first time the CD4+ CD25 low GITR+ CD127+ Treg subpopulation in cancer, and the 2.6 fold increase in positive LN suggests that this Treg subpopulation could be a key player in metastasis. We also found GITRL expression in the CD8 lymphocytes, which may also contribute to the changes of metastatic lymph node microenvironment. These findings make both GITR and GITRL good possible co-candidates for future therapeutical intervention against metastasis and perhaps also as disease evolution biomarkers.

Comparison of immune activation of the COVID vaccines: ChAdOx1, BNT162b2, mRNA-1273, BBIBP-CorV, and Gam-COVID-Vac from serological human samples in Hungary showed higher protection after mRNA-based immunization.

OBJECTIVE: To gain insight into the different protective mechanisms of approved vaccines, this study focuses on the comparison of humoral and cellular immune responses of five widely used vaccines including ChAdOx1 (AZD1222, AstraZeneca), BNT162b2 (Pfizer), mRNA-1273 (Moderna), BBIBP-CorV (Sinopharm), and Gam-COVID-Vac (Sputnik V). MATERIALS AND METHODS: Isolated plasma from 95 volunteers' blood samples was used to measure anti-SARS-CoV-2 humoral and cellular immune responses. Positive controls were recovered patients from COVID-19 (unvaccinated). Specific quantification kits for anti-nucleocapsid IgG, anti-Spike protein IgG, neutralizing antibodies as well as specific SARS-CoV-2 antigens for T-cell activation were used and Spearman correlation and matrix analyses were performed to compare overall immune responses. RESULTS: Nucleocapsid antibodies were significantly higher for the BBIBP-CorV and convalescent group when compared to other vaccines. In contrast, subjects vaccinated with BNT162b2 and mRNA-1273 presented significantly higher anti-spike IgG. In fact, 9.1% of convalescent, 4.5% of Gam-COVID-Vac, 28.6% of ChAdOx1, and 12.5% of BBIBP-CorV volunteers did not generate anti-spike IgG. Similarly, a positive correlation was observed after the neutralization assay. T-cell activation studies showed that mRNA-based vaccines induced a T-cell driven immune response in all cases, while 55% of convalescents,  8% of BNT162b1,  12,5% of mRNA-1273, 9% of Gam-COVID-Vac,  57% of ChAdOx1,  and  56% of BBIBP-CorV subjects presented no cellular response. Further correlation matrix analyses indicated that anti-spike IgG and neutralizing antibodies production, and T-cell activation follow the same trend after immunization. CONCLUSIONS: RNA-based vaccines induced the most robust adaptive immune activation against SARS-CoV-2 by promoting a significantly higher T-cell response, anti-spike IgG and neutralization levels. Vector-based vaccines protected against the virus at a comparable level to convalescent patients.

Arsenic trioxide sensitizes cancer stem cells to chemoradiotherapy. A new approach in the treatment of inoperable glioblastoma multiforme.

PURPOSE: glioblastoma multiforme (GBM) still bears a very dismal prognosis even with complete resection followed by adjuvant chemoradiation. The aim of the current study was to evaluate in vitro the antitumor efficacy of arsenic trioxide (ATO) in combination with ionizing radiation plus temozolomide and bevacizumab against cultured glioblastoma stem-like cells, as possible way to increase the therapeutic index in patients diagnosed with recurrent, therapy-refractory GBM. METHODS: stem-like tumor cells isolated from a GBM biopsy were established by cell proliferation assays and upregulation of stem cell markers, as proven by reverse transcription - polymerase chain reaction (RT-PCR). Low concentrations of ATO were added prior to temozolomide, bevacizumab and ionizing irradiation. RESULTS: molecular analysis showed that cells expressed CXCR4, Oct-3/4 and GAPDH when compared to placental mesenchymal stem cells, as well as nestin, GFAP and neurofilament protein. Low concentrations of ATO led to morphologic differentiation, with fewer stem cells in Go state and differentiation-associated cytochemical features, like increased sensitivity to cytostatic drugs and radiotherapy. CONCLUSION: ATO exposure before conventional postoperative chemoradiotherapy for GBM might increase treatment efficacy. Further in vivo experiments on laboratory animals and analysis of absorption rate and side effects are required.

Cell-specific expression of heat shock proteins in chicken reticulocytes and lymphocytes.

We have found that chicken reticulocytes respond to elevated temperatures by the induction of only one heat shock protein, HSP70, whereas lymphocytes induce the synthesis of all four heat shock proteins (89,000 mol wt, HSP89; 70,000 mol wt, HSP70; 23,000 mol wt, HSP23; and 22,000 mol wt, HSP22). The synthesis of HSP70 in lymphocytes was rapidly induced by small increases in temperature (2 degrees-3 degrees C) and blocked by preincubation with actinomycin D. Proteins normally translated at control temperatures in reticulocytes or lymphocytes were not efficiently translated after incubation at elevated temperatures. The preferential translation of mRNAs that encode the heat shock proteins paralleled a block in the translation of other cellular proteins. This effect was most prominently observed in reticulocytes where heat shock almost completely repressed alpha- and beta-globin synthesis. HSP70 is one of the major nonglobin proteins in chicken reticulocytes, present in the non-heat-shocked cell at approximately 3 X 10(6) molecules per cell. We compared HSP70 from normal and heat-shocked reticulocytes by two-dimensional gel electrophoresis and by digestion with Staphylococcus aureus V8 protease and found no detectable differences to suggest that the P70 in the normal cell is different from the heat shock-induced protein, HSP70. P70 separated by isoelectric focusing gel electrophoresis into two major protein spots, an acidic P70A (apparent pl = 5.95) and a basic P70B (apparent pl = 6.2). We observed a tissue-specific expression of P70A and P70B in lymphocytes and reticulocytes. In lymphocytes, P70A is the major 70,000-mol-wt protein synthesized at normal temperatures whereas only P70B is synthesized at normal temperatures in reticulocytes. Following incubation at elevated temperatures, the synthesis of both HSP70A and HSP70B was rapidly induced in lymphocytes, but synthesis of only HSP70B was induced in reticulocytes.

Interfacial water structure controls protein conformation.

A phenomenological theory of salt-induced Hofmeister phenomena is presented, based on a relation between protein solubility in salt solutions and protein-water interfacial tension. As a generalization of previous treatments, it implies that both kosmotropic salting out and chaotropic salting in are manifested via salt-induced changes of the hydrophobic/hydrophilic properties of protein-water interfaces. The theory is applied to describe the salt-dependent free energy profiles of proteins as a function of their water-exposed surface area. On this basis, three classes of protein conformations have been distinguished, and their existence experimentally demonstrated using the examples of bacteriorhodopsin and myoglobin. The experimental results support the ability of the new formalism to account for the diverse manifestations of salt effects on protein conformation, dynamics, and stability, and to resolve the puzzle of chaotropes stabilizing certain proteins (and other anomalies). It is also shown that the relation between interfacial tension and protein structural stability is straightforwardly linked to protein conformational fluctuations, providing a keystone for the microscopic interpretation of Hofmeister effects. Implications of the results concerning the use of Hofmeister effects in the experimental study of protein function are discussed.

Capturing nuclear sequence-specific DNA-binding proteins by using simian virus 40-derived minichromosomes.

We have used recombinant simian virus 40 (SV40) minichromosomes to retrieve sequence-specific DNA-binding proteins derived from the cell nucleus of COS-7 cells. We showed that the transcription factors AP-1 and Sp1 are stably bound to the SV40 DNA late in viral infection. Under similar conditions, minichromosomes carrying the rat insulin (rINS1) enhancer, which is under negative regulation in COS-7 cells, bound two proteins which mapped to distinct regions of the rINS1 enhancer. The SV40 P element competed for one of these proteins which bound to the region from -198 to -230. This factor may be related to AP-1. The other factor selectively bound a regulatory element in the region from -92 to -124 of the insulin enhancer. These proteins may play a role in regulating the rINS1 enhancer function.

Methods to Study Autophagy in Zebrafish.

Autophagy (cellular self-eating) is a highly regulated degradation process of the eukaryotic cell during which parts of the cytoplasm are delivered into, and broken down within, the lysosomal compartment. The process serves as a main route for the elimination of superfluous and damaged cellular constituents, thereby mediating macromolecular and organellar turnover. In addition to maintaining cellular homeostasis, autophagy is involved in various other cellular and developmental processes by degrading specific regulatory proteins, and contributing to the clearance of intracellular pathogens. The physiological roles and pathological involvement of autophagy can be effectively studied in divergent eukaryotic model systems ranging from yeast to mice. Such a tractable animal modelapplied only recently for autophagy researchis the zebrafish Danio rerio, which also facilitates the analysis of more specific biological processes such as tissue regeneration. In this chapter, we overview the main methods and tools that are used to monitor autophagic structures and to assay autophagic responses in this vertebrate organism. We place emphasis on genetic (functional) approaches applied for exploring novel cellular and developmental roles of the autophagic process.

The significance of micro- and macrovascular biomarkers on cardiovascular outcome in chronic kidney disease: a prospective cohort study.

Measures of small and large artery dysfunction have not been investigated in a single cohort for the prediction of cardiovascular (CV) events in patients with nondialysed (ND) chronic kidney disease (CKD). This prospective cohort study aimed to determine whether central pulse wave velocity (cPWV), central pulse pressure (CPP) or microvascular post-occlusive reactive hyperaemia area (PORHHA) independently predict CV events and mortality in CKD-ND. A total of 94 stage 1-5 CKD-ND (65.3±13.1 years; estimated glomerular filtration rate 35.3 (22.8-49.4) ml min(-1) per 1.73 m(2)) patients were followed-up for a median of 52 (36-65) months and had baseline cPWV and CPP measured by applanation tonometry and PORHHA by laser Doppler flowmetry. Multiple failure time Cox regression models were used to determine the predictive role of vascular parameters on CV mortality and events. Based on multiple linear regressions, baseline age, diabetes, CV disease, and systolic blood pressure (SBP) were independently related to cPWV (R(2)=0.3), SBP and PORHHA to CPP (R(2)=0.45), whereas CPP was the only parameter independently related to PORHHA (R(2)=0.16, all P<0.05). During follow-up, 41 CV events occurred (14 CV deaths). In univariate analyses, cPWV (1.07 (1.02-1.13) per m s(-1)), CPP (1.04 (1.01-1.07) per mm Hg) and lnPORHHA (0.70 (0.58-0.85) per ln(PU × s)) were all related to the outcome. Baseline diabetes (HR 3.07 (1.65-5.68)), lnFGF23 (fibroblast growth factor-23; 1.86 (1.13-3.06) per RU ml(-1)) and CPP (1.04 (1.01-1.07) per mm Hg) were independent predictors of CV events. The impaired pulsatile component of large arteries (CPP) independently of other vascular markers (cPWV, PORHHA) predicted CV outcomes in CKD-ND. CPP may integrate the information provided by cPWV and PORHHA.

Orthomyxovirus replication, transcription, and polyadenylation.

Efficient in vitro and in vivo systems are now in place to study the role of viral proteins in replication and/or transcription, the regulation of these processes, polyadenylation of viral mRNAs, the viral promoter structures, or the significance of noncoding regions for virus replication. In this chapter, we review the status of current knowledge of the orthomyxovirus RNA synthesis.

Modeling the dynamics of a tracer particle in an elastic active gel.

The internal dynamics of active gels both in artificial (in vitro) model systems and inside the cytoskeleton of living cells has been extensively studied with experiments of recent years. These dynamics are probed using tracer particles embedded in the network of biopolymers together with molecular motors, and distinct nonthermal behavior is observed. We present a theoretical model of the dynamics of a trapped active particle, which allows us to quantify the deviations from equilibrium behavior, using both analytic and numerical calculations. We map the different regimes of dynamics in this system and highlight the different manifestations of activity: breakdown of the virial theorem and equipartition, different elasticity-dependent "effective temperatures," and distinct non-Gaussian distributions. Our results shed light on puzzling observations in active gel experiments and provide physical interpretation of existing observations, as well as predictions for future studies.

DNA sequence and functional characterization of the human and rat epidermal growth factor promoter: regulation by cell growth.

Epidermal growth factor (EGF) regulates cell growth and differentiation through intracellular transduction networks activated by its tyrosine kinase receptor, EGFR. In this report we describe the structure and DNA sequence of transcriptional control regions from both human and Wistar-rat single copy EGF genes and their functional analysis in epithelial cell cultures. By sequence comparison we show these proximal gene regions have remained conserved in evolution to -640 (relative to the rodent mRNA initiation site), where similarity is interrupted by a rodent interspersed-repeat element (SINE). Transcript mapping reveals complexity in EGF initiation site selection: whereas a single rat liver initiation site (+1) appears 30bp 3' to the TTTAA element, an additional upstream site is detected in kidney RNA at -14. In contrast, in human RNA a single initiation is observed, which is displaced 12bp 3' to the rodent RNA terminus. Both promoters were defined in transient expression assays. Our results show the human promoter to be at least 20-fold more active than the equivalent rodent sequence, although both are activated during cell proliferation and negatively regulated in contact inhibited and quiescent cultures. The results indicate EGF gene expression and cell division are temporally linked, suggesting its promoter comprises a growth responsive regulatory domain.

Expression of epidermal growth factor and its receptor in cirrhotic liver disease.

Polypeptide growth factors, including epidermal growth factor (EGF), play a central role in regulating hepatocyte growth both in vivo and in primary culture. To characterize EGF gene expression in the pathogenesis of regenerative cirrhotic fibrosis, we employed biotinylated antisense oligonucleotide probes to localize hepatic mRNA transcripts in situ. In control tissue and regenerative hepatic nodules, EGF receptor (EGFR) mRNA transcripts were expressed constitutively. In contrast, oligonucleotide probes targeting the human EGF coding region showed that EGF transcription was extremely low in control liver but was highly elevated and localized to regenerative hepatic nodules and bile duct epithelia of cirrhotic liver. To determine whether EGF mRNA accumulation accompanied a comparable increase in the EGF peptide, we performed immunohistochemistry using an antibody specific for the nonprocessed peptide aminoterminus. We observed that positive localized EGF staining paralleled its mRNA transcript. These results indicate that EGF upregulation is a characteristic of cirrhotic liver disease and suggest that persistent de novo ligand synthesis and its signaling contribute to an autocrine-mediated hepatocyte proliferation within the regenerative nodule.

Isolation and genomic analysis of the rat polymeric immunoglobulin receptor gene terminal domain and transcriptional control region.

The polymeric immunoglobulin receptor (pIgR) transports IgA and IgM across secretory epithelial cells and is essential in external immunity maintenance. We report here the structural characterization of the single-copy rat gene distributed over 30 kb of chromosomal DNA and analysis of its transcriptional control region. RNA sequencing and genomic analysis show a 5' terminal region originates at a major (+1) and a minor site producing an unusual 124-bp nontranslated exon I separated from a small 96-bp initiator ATG coding exon II by a 7.5-kb intron. The pIgR 5' region comprises a structured promoter with abundant helix-loop-helix (bHLH) cis elements positioned within an equivalent internal -70, -290, -528, and three centered at -745. The three latter bHLH elements each occur within 30-bp repeats at -690 to -780. Transient expression assays show a 1.3-kb 5' region is sufficient to drive expression in rat primary hepatocyte monolayer cultures, transformed human hepatic (HepG2) cells, and a mammary epithelial tumor cell line MCF-7, but is inactive in the rodent fibroblast 3T3 cell line. A minimal transcriptional promoter domain was deduced from sequentially deleted vectors revealing a +40 to -922 sequence to be sufficient for full activity. Further deletions within this region yield incremental losses in cis activity, indicating that multiple subregions comprise an extended transcriptional control region.

Prevalence of the carbapenemase gene (cfiA) among clinical and normal flora isolates of Bacteroides species in Hungary.

The carbapenemase gene (cfiA) was detected in 4 (5.7%) of 70 clinical isolates of Bacteroides fragilis from different parts of Hungary. Among 24 other Bacteroides species isolated from infectious processes or from normal faecal flora, none was cfiA-positive. The MIC of imipenem and meropenem for all cfiA-positive B. fragilis isolates was < or =0.25 mg/L, but 17% of the B. fragilis and 46% of the non-fragilis Bacteroides isolates exhibited reduced susceptibility to imipenem (MICs 0.5-2 mg/L). Only one of these isolates produced increased levels of beta-lactamase. No difference was observed in the outer-membrane proteins of B. fragilis isolates that harboured the cfiA gene and those with reduced susceptibility to imipenem.

Adaptation of composition and biophysical properties of phospholipids to temperature by the Crustacean, Gammarus spp.

The compositions of lipid classes as well as the molecular species composition of subclasses (diacyl, alkylacyl, and alkenylacyl forms) of choline and ethanolamine phosphoglycerides in marine amphipod crustaceans, Gammarus spp., collected in the Baltic Sea at 8 and 15 degrees C, were studied in relation to environmental temperature. The structural order of phospholipid multibilayers was also determined. Environmental temperature had little effect on fatty acid composition. The level of some polyunsaturated fatty acids, such as 20:4, even increased in choline and ethanolamine phosphoglycerides at 15 degrees C. Ethanolamine phosphoglycerides were rich in alkenylacyl forms, especially in crustaceans collected at 15 degrees C. The accumulation of sn-1 monoenic, sn-2 polyenic diacyl, alkyl, and alkenylacyl phosphatidylethanolamines and diacyl phosphatidylcholines was observed at 8 degrees C. The phospholipid vesicles of crustaceans collected at 8 degrees C were more disordered than expected compared to those obtained from animals collected at 15 degrees C. It was concluded that, in addition to variations in the levels of sn-1 monoenic and sn-2 polyenic phospholipid molecular species with temperature, ethanolamine plasmalogens may play a role in controlling membrane biophysical properties in marine amphipod crustaceans.