First demonstration of 30 eVee ionization energy resolution with Ricochet germanium cryogenic bolometers

The future Ricochet experiment aims to search for new physics in the electroweak sector by measuring the Coherent Elastic Neutrino-Nucleus Scattering process from reactor antineutrinos with high precision down to the sub-100 eV nuclear recoil energy range. While the Ricochet collaboration is currently building the experimental setup at the reactor site, it is also finalizing the cryogenic detector arrays that will be integrated into the cryostat at the Institut Laue Langevin in early 2024. In this paper, we report on recent progress from the Ge cryogenic detector technology, called the CryoCube. More specifically, we present the first demonstration of a 30 eVee (electron equivalent) baseline ionization resolution (RMS) achieved with an early design of the detector assembly and its dedicated High Electron Mobility Transistor (HEMT) based front-end electronics with a total input capacitance of about 40 pF. This represents an order of magnitude improvement over the best ionization resolutions obtained on similar phonon-and-ionization germanium cryogenic detectors from the EDELWEISS and SuperCDMS dark matter experiments, and a factor of three improvement compared to the first fully-cryogenic HEMT-based preamplifier coupled to a CDMS-II germanium detector with a total input capacitance of 250 pF. Additionally, we discuss the implications of these results in the context of the future Ricochet experiment and its expected background mitigation performance.

Measurement of the 2νββ Decay Rate and Spectral Shape of ^{100}Mo from the CUPID-Mo Experiment

Neutrinoless double beta decay (0νββ) is a yet unobserved nuclear process that would demonstrate Lepton number violation, a clear evidence of beyond standard model physics. The process two neutrino double beta decay (2νββ) is allowed by the standard model and has been measured in numerous experiments. In this Letter, we report a measurement of 2νββ decay half-life of ^{100}Mo to the ground state of ^{100}Ru of [7.07±0.02(stat)±0.11(syst)]×10^{18}  yr by the CUPID-Mo experiment. With a relative precision of ±1.6% this is the most precise measurement to date of a 2νββ decay rate in ^{100}Mo. In addition, we constrain higher-order corrections to the spectral shape, which provides complementary nuclear structure information. We report a novel measurement of the shape factor ξ_{3,1}=0.45±0.03(stat)±0.05(syst) based on a constraint on the ratio of higher-order terms from theory, which can be reliably calculated. This is compared to theoretical predictions for different nuclear models. We also extract the first value for the effective axial vector coupling constant obtained from a spectral shape study of 2νββ decay.

Combining Genome Surveillance and Metadata To Characterize the Diversity of Staphylococcus aureus Circulating in an Italian Hospital over a 9-Year Period

Staphylococcus aureus is an opportunistic pathogen and a leading cause of morbidity and mortality worldwide. Genomic-based surveillance has greatly improved our ability to track the emergence and spread of high-risk clones, but the full potential of genomic data is only reached when used in conjunction with detailed metadata. Here, we demonstrate the utility of an integrated approach by leveraging a curated collection of clinical and epidemiological metadata of S. aureus in the San Matteo Hospital (Italy) through a semisupervised clustering strategy. We sequenced 226 sepsis S. aureus samples, recovered over a period of 9 years. By using existing antibiotic profiling data, we selected strains that capture the full diversity of the population. Genome analysis revealed 49 sequence types, 16 of which are novel. Comparative genomic analyses of hospital- and community-acquired infection ruled out the existence of genomic features differentiating them, while evolutionary analyses of genes and traits of interest highlighted different dynamics of acquisition and loss between antibiotic resistance and virulence genes. Finally, highly resistant clones belonging to clonal complexes (CC) 8 and 22 were found to be responsible for abundant infections and deaths, while the highly virulent CC30 was responsible for rare but deadly episodes of infections. IMPORTANCE Genome sequencing is an important tool in clinical microbiology, as it allows in-depth characterization of isolates of interest and can propel genome-based surveillance studies. Such studies can benefit from ad hoc methods of sample selection to capture the genomic diversity present in a data set. Here, we present an approach based on clustering of antibiotic resistance profiles that allows optimal sample selection for bacterial genomic surveillance. We apply the method to a 9-year collection of Staphylococcus aureus from a large hospital in northern Italy. Our method allows us to sequence the genomes of a large variety of strains of this important pathogen, which we then leverage to characterize the epidemiology in the hospital and to perform evolutionary analyses on genes and traits of interest. These analyses highlight different dynamics of acquisition and loss between antibiotic resistance and virulence genes.

Determining g_{A}/g_{V} with High-Resolution Spectral Measurements Using a LiInSe_{2} Bolometer

Neutrinoless double beta decay (0νββ) processes sample a wide range of intermediate forbidden nuclear transitions, which may be impacted by quenching of the axial vector coupling constant (g_{A}/g_{V}), the uncertainty of which plays a pivotal role in determining the sensitivity reach of 0νββ experiments. In this Letter, we present measurements performed on a high-resolution LiInSe_{2} bolometer in a "source=detector" configuration to measure the spectral shape of the fourfold forbidden β decay of ^{115}In. The value of g_{A}/g_{V} is determined by comparing the spectral shape of theoretical predictions to the experimental β spectrum taking into account various simulated background components as well as a variety of detector effects. We find evidence of quenching of g_{A}/g_{V} at >5σ with a model-dependent quenching factor of 0.655±0.002 as compared to the free-nucleon value for the interacting shell model. We also measured the ^{115}In half-life to be [5.18±0.06(stat)_{-0.015}^{+0.005}(sys)]×10^{14}  yr within the interacting shell model framework. This Letter demonstrates the power of the bolometeric technique to perform precision nuclear physics single-β decay measurements, which along with improved nuclear modeling can help reduce the uncertainties in the calculation of several decay nuclear matrix elements including those used in 0νββ sensitivity calculations.

New Limit for Neutrinoless Double-Beta Decay of ^{100}Mo from the CUPID-Mo Experiment

The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale bolometric 0νββ experiment. It consists of a 4.2 kg array of 20 enriched Li_{2}^{100}MoO_{4} scintillating bolometers to search for the lepton-number-violating process of 0νββ decay in ^{100}Mo. With more than one year of operation (^{100}Mo exposure of 1.17  kg×yr for physics data), no event in the region of interest and, hence, no evidence for 0νββ is observed. We report a new limit on the half-life of 0νββ decay in ^{100}Mo of T_{1/2}>1.5×10^{24}  yr at 90% C.I. The limit corresponds to an effective Majorana neutrino mass ⟨m_{ββ}⟩<(0.31-0.54)  eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.

First Germanium-Based Constraints on Sub-MeV Dark Matter with the EDELWEISS Experiment

We present the first Ge-based constraints on sub-MeV/c^{2} dark matter (DM) particles interacting with electrons using a 33.4 g Ge cryogenic detector with a 0.53 electron-hole pair (rms) resolution, operated underground at the Laboratoire Souterrain de Modane. Competitive constraints are set on the DM-electron scattering cross section, as well as on the kinetic mixing parameter of dark photons down to 1  eV/c^{2}. In particular, the most stringent limits are set for dark photon DM in the 6 to 9  eV/c^{2} range. These results demonstrate the high relevance of Ge cryogenic detectors for the search of DM-induced eV-scale electron signals.

Ixodid ticks on wild donkeys in a Mediterranean nature reserve (Asinara National Park): diversity and risk factors

The Sardinian coloured donkey Equus asinus (Perissodactyla: Equidae) and its albino colour morph represent the wildlife species most typical of the island of Asinara. This Mediterranean island represents a favourable context for ticks and tick-borne diseases; however, knowledge of the tick fauna on Asinara is scarce. A total of 106 Sardinian donkeys were inspected for tick infestation from June to November 2015. All ticks found were collected, classified by stage and sex, and identified to species level. The level of infestation of each donkey was determined; both the overall tick infestation and infestations of each detected species were classified on a scale of 1-3 to give an infestation score (IS). Overall, 256 hard ticks were collected from 60 of 106 donkeys (56.6%). Rhipicephalus bursa, Haemaphysalis punctata and Hyalomma marginatum (all: Ixodida: Ixodidae) infested 26.4%, 28.3% and 6.6% of donkeys, respectively. Different variables affected the IS. With reference to overall tick infestation, a higher IS was observed in donkeys grazing on grassland and Mediterranean shrubland and in albino donkeys compared with coloured donkeys. The collected ticks included species involved in the transmission of pathogens to humans, which highlights the risks for public health in a tourist destination such as Asinara National Park.

Toxoplasma gondii Antibodies in Bulk Tank Milk Samples of Caprine Dairy Herds

A major public health issue, Toxoplasma gondii infection can affect humans mainly via the consumption of animal products from certain species, including small ruminants. Therefore, a regular monitoring of the infection in ovine and caprine populations is advisable for the control of human and animal toxoplasmosis. Antibody detection in individual and bulk tank milk (BTM) may represent a valid alternative to serological analysis, in that its collection is easy and does not affect animal welfare. Many serological tools for milk analysis have already been validated for several parasites, including Apicomplexa. Thus, the aim of the present study was to obtain epidemiological data on T. gondii infection through the detection of antibodies in BTM of dairy goat herds from an important area for caprine dairy production (northern Italy). The performance of a commercial ELISA was first evaluated for analysis of caprine milk samples, using a panel of serum-milk pairs of goats naturally infected by T. gondii. The analysis of BTM confirmed the presence of anti- T. gondii antibodies in 59% of the samples. Toxoplasma gondii antibody positivity was more frequently found in goats reared on farms under extensive (64.9%) or semi-intensive systems (68.7%) in comparison with intensive farms (51.1%). Analysis of milk was a valid alternative to serological tests, being easily applied in large-scale epidemiological surveys and for continuous monitoring of T. gondii infection.

First Results from CUORE: A Search for Lepton Number Violation via 0νββ Decay of ^{130}Te

The CUORE experiment, a ton-scale cryogenic bolometer array, recently began operation at the Laboratori Nazionali del Gran Sasso in Italy. The array represents a significant advancement in this technology, and in this work we apply it for the first time to a high-sensitivity search for a lepton-number-violating process: ^{130}Te neutrinoless double-beta decay. Examining a total TeO_{2} exposure of 86.3 kg yr, characterized by an effective energy resolution of (7.7±0.5)  keV FWHM and a background in the region of interest of (0.014±0.002)  counts/(keV kg yr), we find no evidence for neutrinoless double-beta decay. Including systematic uncertainties, we place a lower limit on the decay half-life of T_{1/2}^{0ν}(^{130}Te)>1.3×10^{25}  yr (90% C.L.); the median statistical sensitivity of this search is 7.0×10^{24}  yr. Combining this result with those of two earlier experiments, Cuoricino and CUORE-0, we find T_{1/2}^{0ν}(^{130}Te)>1.5×10^{25}  yr (90% C.L.), which is the most stringent limit to date on this decay. Interpreting this result as a limit on the effective Majorana neutrino mass, we find m_{ββ}<(110-520)  meV, where the range reflects the nuclear matrix element estimates employed.

Development of 100 Mo -containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search

This paper reports on the development of a technology involving 100 Mo -enriched scintillating bolometers, compatible with the goals of CUPID, a proposed next-generation bolometric experiment to search for neutrinoless double-beta decay. Large mass ( ∼ 1 kg ), high optical quality, radiopure 100 Mo -containing zinc and lithium molybdate crystals have been produced and used to develop high performance single detector modules based on 0.2-0.4 kg scintillating bolometers. In particular, the energy resolution of the lithium molybdate detectors near the Q-value of the double-beta transition of 100 Mo (3034 keV) is 4-6 keV FWHM. The rejection of the α -induced dominant background above 2.6 MeV is better than 8 σ . Less than 10 μ Bq/kg activity of 232 Th ( 228 Th ) and 226 Ra in the crystals is ensured by boule recrystallization. The potential of 100 Mo -enriched scintillating bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only 10 kg × d exposure: the two neutrino double-beta decay half-life of 100 Mo has been measured with the up-to-date highest accuracy as T 1 / 2 = [6.90 ± 0.15(stat.) ± 0.37(syst.)] × 10 18 years . Both crystallization and detector technologies favor lithium molybdate, which has been selected for the ongoing construction of the CUPID-0/Mo demonstrator, containing several kg of 100 Mo .

Cross-sectional survey on Tritrichomonas foetus infection in Italian cats

The feline genotype of Tritrichomonas foetus is a widespread cause of large-bowel diarrhoea in cats. The aim of this study was to determine the prevalence of the T. foetus infection in cat populations across Italy. Fresh, individual faecal samples were collected from 267 cats, kept in different environments (i.e., private households, breeding structures, municipal catteries and colonies) in three different sites across Italy. The faecal samples were tested by PCR to detect T. foetus. Moreover, the same samples were subjected to a concentration-flotation technique and a commercial direct fluorescent-antibody (DFA) test to detect additional enteric parasites, including Giardia duodenalis. The overall prevalence of T. foetus infection was 5.2%. All the infected cats showed diarrhoea at the time of sampling: 9 out of 14 positive cats were co-infected with G. duodenalis, 1 with Toxocara cati and 3 with Dipylidium caninum. The risk factor analysis showed that not only the breed, but also co-infections with G. duodenalis and Dipylidium caninum were significantly associated with the presence of T. foetus. This study confirms the presence of T. foetus in cats living in Italy, suggesting that this protozoan parasite should always be included in the differential diagnosis of patients referred with large-bowel disease symptoms, especially if they were purebred animals, or affected by other enteric protozoa, such as G. duodenalis.

Quality of sleep in allergic children and their parents

BACKGROUND

Quality of sleep is essential for physical and mental health and influences the perception of the patient's well-being during the day. In patients with chronic allergic diseases sleep disorders may increase the severity of the condition, complicate the management and impair their quality of life. When children are concerned, their parents are also affected by the problem. We evaluated the presence of disrupted sleep in parents of children with atopic disorders, and its relationship with clinical features and the presence of disturbed sleep in children.

METHODS

Parents of children suffering from allergic diseases were recruited from the Pediatric Allergy Units of Parma University. Evaluation of sleep in parents was based on the Pittsburg Sleep Quality Index (PSQI), while in children it was based on the Sleep Disturbance Scale for Children (SDSC).

RESULTS

Of the 102 parents invited, 92 filled in the questionnaire. Only the questionnaires with more than a 95% completion rate were considered for analysis. PSQI mean score in parents was 6.6 (SD 2.6); 75.6% of them had a PSQI ≥ 5, indicating that most parents had a sleep quality perceived as bad. The PSQI ≥ 5 was more common in parents of children with asthma and rhinitis. In children, SDSC mean score was 42.1 (SD: 9.4); 62.3% had a total score ≥ 39. The quality of sleep in parents and children was significantly correlated (p<0.001).

CONCLUSION

These findings make it apparent that an alteration of sleep in children can also affect the parents. Such effect further weighs the burden of respiratory allergy and needs to be considered in future studies.

Italian study on buckwheat allergy: prevalence and clinical features of buckwheat-sensitized patients in Italy

Buckwheat allergy is considered a rare food allergy outside of Asia. In Europe, buckwheat has been described mainly as a hidden allergen. Data on the prevalence of buckwheat hypersensitivity in non-Asian countries is very poor. The aim of this multicenter study was to evaluate the prevalence of buckwheat sensitization and its association with other sensitizations among patients referred to allergy clinics in different geographic areas of Italy. All patients referred to 18 Italian allergy clinics from February through April 2011 were included in the study and evaluated for sensitization to buckwheat and other allergens depending on their clinical history. A total of 1,954 patients were included in the study and 61.3 percent of them were atopic. Mean prevalence of buckwheat sensitization was 3.6 percent with significant difference between Northern (4.5 percent), Central (2.2 percent) and Southern (2.8 percent) regions. This is, to our knowledge, the largest epidemiological survey on buckwheat allergy reported outside of Asia. Buckwheat is an emerging allergen in Italy, being more frequently associated to sensitization in Northern regions.

Allergen immunotherapy: clinical and practical education of Italian trainees in allergy and clinical immunology schools

We performed a survey, based on a questionnaire including 20 items, submitted anonymously to Italian trainees in Allergology and Clinical Immunology, in order to obtain information about their specific allergen immunotherapy (AIT) practices. The questionnaire was sent to 40 trainees, who had attended the last two years of the training course. Thirty-four subjects (mean age: 27 years, 65% females) adequately completed the survey. The answers to the questionnaire showed that only 60% of the training programs included lectures on AIT. Among the trainees using AIT, only 40% declared being able to prescribe it independently, while 60% were guided by a tutor. Of the trainees who were able to prescribe AIT autonomously, 60% were familiar with both routes of administration, i.e. subcutaneous (SCIT) and sublingual immunotherapy (SLIT), while 25% of these used only SLIT. In 80% of the training institutions involved, the trainees could attend a dedicated AIT outpatient ward for SCIT administration; only 40% administered AIT personally, and in half of these cases, they were guided by a tutor. Only 70% of trainees had experience in the follow-up of patients still under treatment and of patients who had completed treatment. Analysis of the answers obtained for questions on venom immunotherapy (VIT) showed that, in 90% of cases, the trainees attended a dedicated outpatients ward where VIT is administered, but with a role limited to observation/cooperation. Only 30% were involved in the follow-up of patients who were under treatment or who had completed VIT. Only 20% of the trainees felt confident enough about VIT to prescribe this treatment independently, 80% knew there were several administration protocols, and the majority prescribed products from three different manufacturers. These findings suggest that there is significant room for improving the instructions provided regarding allergology and clinical immunology to trainees in Italy with respect to AIT.

How much specific is the association between hymenoptera venom allergy and mastocytosis?

BACKGROUND

The preferential association of mastocytosis with hymenoptera sting reactions is well known, but there is no data on the prevalence of clonal mast cell disorders in subjects with severe systemic reactions due to foods or drugs.

METHODS

Patients with food- or drug-induced severe systemic reactions, including anaphylaxis, and increased serum tryptase were studied for the presence of mastocytosis, and compared with a population of patients with hymenoptera allergy. The aetiological role of foods or drugs was assessed according to current recommendations. Systemic reactions were graded in severity according to the procedure described by Mueller. Serum tryptase was considered increased if the level was >11.4 ng/ml. Subjects with increased tryptase had dermatological evaluation and Bone marrow(BM) aspirate-biopsy, which included histology/cytology, flow cytometry and detection of KIT mutations.

RESULTS

A total of 137 subjects (57 male, mean age 42 years) were studied. Of them, 86 proved positive for drugs and 51 for foods. Overall, out of 137 patients, only nine (6.6%) had a basal tryptase >11.4 ng/ml, and only two (1.5%) were diagnosed with mastocytosis. This was clearly different from patients with hymenoptera allergy, where 13.9% had elevated tryptase and 11.1% had a clonal mast cell disorder.

CONCLUSION

The association of clonal mast cell disorders with hymenoptera allergy seems to be more specific than that with food- or drug-induced systemic reactions.

New limit on the neutrinoless betabeta decay of 130Te

We report the present results of CUORICINO, a search for neutrinoless double-beta (0nu betabeta) decay of 130Te. The detector is an array of 62 TeO2 bolometers with a total active mass of 40.7 kg. The array is cooled by a dilution refrigerator shielded from environmental radioactivity and energetic neutrons, operated at approximately 8 mK in the Gran Sasso Underground Laboratory. No evidence for (0nu betabeta) decay was found and a new lower limit, T(1/2)(0nu) > or = 1.8 x 10(24) yr (90% C.L.) is set, corresponding to [m(nu)] < or = 0.2 to 1.1 eV, depending on the theoretical nuclear matrix elements used in the analysis.

Reduction and alkylation of proteins in preparation of two-dimensional map analysis: why, when, and how?

The standard procedure adopted up to the present in proteome analysis calls for just reduction prior to the isoelectric focusing/immobilized pH gradient (IEF/IPG) step, followed by a second reduction/alkylation step in between the first and second dimension, in preparation for the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) step. This protocol is far from being optimal. It is here demonstrated, by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry, that failure to reduce and alkylate proteins prior to any electrophoretic step (including the first dimension) results in a large number of spurious spots in the alkaline pH region, due to "scrambled" disulfide bridges among like and unlike chains. This series of artefactual spots comprises not only dimers, but an impressive series of oligomers (up to nonamers) in the case of simple polypeptides such as the human alpha- and beta-globin chains, which possess only one (alpha-) or two (beta-) -SH groups. As a result, misplaced spots are to be found in the resulting two-dimensional (2-D) map, if performed with the wrong protocol. The number of such artefactual spots can be impressively large. In the case of analysis of complex samples, such as human plasma, it is additionally shown that failure to alkylate proteins results in a substantial loss of spots in the alkaline gel region, possibly due to the fact that these proteins, at their pI, regenerate their disulfide bridges with concomitant formation of macroaggregates which become entangled with and trapped within the polyacrylamide gel fibers. This strongly quenches their transfer in the subsequent SDS-PAGE step.

The effect of protease inhibitors on the two-dimensional electrophoresis pattern of red blood cell membranes

The last few years have brought dramatic improvements for sample preparation and solubilization of protein for electrophoretic analyses. The use of reagents such as thiourea and novel sulfobetaine surfactants increases the total number of proteins able to be visualized from a complex mixture such as a cell lysate and also allows more hydrophobic membrane proteins to be resolved. As the red blood cell (RBC) contain no organelles, it is an ideal source of relatively pure plasma membrane for protein solubilization studies. In addition, there are a number of diseases related to abnormalities of RBCs proteins, thus it is of medical relevance as well as a test sample for technology development. However, the procedure for purifying RBC membranes is rather time-consuming and is normally carried out under almost physiological conditions, which can be conducive to proteolytic degradation of the membrane proteins. Significant differences in two-dimensional (2-D) patterns with and without protease inhibitors in sample preparation are demonstrated. In addition, is shown that preparation of RBC membranes with sodium carbonate, pH 11, leads to multimeric complexes of hemoglobin and causes hemoglobin to be irreversibly attached to the membrane. When using immobilized pH gradients (IPG) as the first dimension, it is demonstrated that the spectrins (large, filamentous proteins of 280 kDa) are lost from the 2-D map unless active, instead of passive, sample hydration into the IPG strip is adopted.

Capillary electrophoresis of peptides and proteins in isoelectric buffers: an update

Capillary electrophoresis in acidic, isoelectric buffers is a novel methodology allowing fast protein and peptide analysis in uncoated capillaries. Due to the low pH adopted and to the use of dynamic coating with cellulose derivatives, silanol ionization is essentially suppressed and little interaction of macromolecules with the untreated wall occurs. In addition, due to the low conductivity of quasi-stationary, isoelectric buffers, high-voltage gradients can be applied (up to 800 V/cm) permitting fast peptide analysis with a high resolving power due to minimal diffusional peak spreading. Four such buffers are here described: cysteic acid (Cys-A, pI 1.85), iminodiacetic acid (IDA, pI 2.23), aspartic acid (Asp, pI 2.77) and glutamic acid (Glu, pI 3.22). A number of applications are reported, ranging from food analysis to the study of folding/unfolding transitions of proteins.

General experimental aspects of the use of isoelectric buffers in capillary electrophoresis

Four acidic, isoelectric buffers, for peptide and protein separations, have been recently described and adopted in capillary zone electrophoresis: cysteic acid [Cys-A, isoelectric point (pI) 1.85], iminodiacetic acid (IDA, pI 2.23), aspartic acid (Asp, pI 2.77) and glutamic acid (Glu, pI 3.22). These four buffers allow to explore an acidic portion of the titration curves of macroions, covering about 1.6 pH units (from pH 1.85 to ca. 3.45), thus permitting resolution of compounds having coincident titration curves at a given pH value. Given the rather acidic pI values of these buffers, their long-term stability has been investigated, by monitoring pH and conductivity changes upon increasing storage times. When dissolved in plain water, all four buffers appear to give constant pH and conductivity readings up to 15 days; after that, the conductivity keeps steadily increasing in a similar fashion. The same parameters, when the same buffers are dissolved in 6 M urea, appear to be stable for only one week, with the conductivity progressively augmenting after this period. A similar behaviour is exhibited by histidine (pI 7.70), a neutral, isoelectric buffer adopted for separation of DNA fragments. By mass spectrometry, Cys-A shows minute amounts (ca. 1%) of a degradation product after ageing for 3 weeks; in the same time period, Glu is extensively degraded (20%). No degradation species could be detected in IDA and Asp solutions. It is additionally shown that the acidic buffers are not quite stationary in the electric field, but can be transported at progressively higher rates (according to the pI value) from the cathodic to the anodic vessel. This is due to the fact that, at their respective pI values, a fraction of the amphotere has to be negatively charged in order to provide counterions to the excess of protons due to bulk water dissociation. Guidelines are given for the proper use and storage of such buffers.

Capillary electrophoresis of peptides and proteins in acidic, isoelectric buffers: recent developments

The use of isoelectric buffers in capillary zone electrophoresis is here reviewed. Such buffers allow delivery of very high voltage gradients (up to 1000 V/cm in relatively large bore capillaries, e.g. 75-100 microm I.D.), permitting separations of the order of a few minutes and thus conserving (in fact favouring) very high resolution due to minimal, diffusion-driven, peak spreading. Isoelectric Asp (pI 2.77 at 50 mM concentration and 25 degrees C) provides a medium of high resolving power for generating peptide maps. In difficult cases, of coincident titration curves, the pH can be moved up to higher values (e.g. pH 3.0 for 30 mM Asp) thus eliciting separation of unresolved peptides at pH 2.77. This was illustrated by running peptide maps of tryptic digests of human beta globin chains. Also imino diacetic acid (pI 2.33 at 50 mM concentration) allows generation of high resolution peptide maps. Isoelectric Asp, in presence of 7 M urea and 0.5% hydroxyethyl cellulose (Mn = 27 000 Da) is also the preferred medium for fast separation and analysis of storage proteins in cereals, such as gliadins in soft and durum wheat and zeins in maize. A solution of 50 mM iminodiacetic acid (pI 2.23) containing 7 M urea and 0.5% hydroxyethylcellulose (apparent pH 3.2) is effectively used as background electrolyte for fast separation of heme-free, denatured globin (alpha and beta) chains. In the presence of neutral to neutral amino acid substitutions, it is additionally shown that the inclusion of 3% surfactant (Tween 20) in the sample and background electrolyte induces the separation of the wild-type and mutant chains, probably by a mechanism of hydrophobic interaction of the more hydrophobic mutant with the detergent micelle, via a mechanism similar to 'micellar electrokinetic chromatography'.

Variety identification in maize lines via capillary electrophoresis of zeins in isoelectric acidic buffers

Zeins (the prolamins or seed storage proteins in maize) have been used to characterize and identify different genotypes. Zeins were fractionated by capillary zone electrophoresis in acidic, amphoteric buffers, which represent a medium of moderate conductivity and are thus compatible with higher voltage gradients. The running buffer consisted of 40 mM isoelectric aspartic acid, in presence of 6 M urea and 0.5% hydroxyethyl cellulose (apparent pH: 3.8; pI in the absence of urea: 2.77). Thirty-one different zein peaks were mapped out of a total of 21 different maize genotypes. Each of them typically exhibited seven to twelve peaks, with some genotypes showing up to 20 zein bands. Due to slightly changing elution times, caused by a lack of reproducibility of the electroendoosmotic flow in uncoated silica surfaces, correct peak assignment and alignment among different runs was obtained by multivariate statistical analysis. The present method compares well, both in resolution and total number of peaks, with current protocols adopted for screening of maize inbreds, which consist of isoelectric focusing in agarose gels.

Identification of maize lines via capillary electrophoresis of zeins in isoelectric, acidic buffers

Modified capillary zone electrophoresis of zeins in strongly acidic, isoelectric buffers is reported for screening of maize (Zea mays L.) lines. The optimized background electrolyte contained 40 mM aspartic acid (pH = pI = 2.77), 8 M urea and 0.5% short-chain hydroxyethylcellulose (Mn 27000 Da) (apparent pH in 8 M urea: 3.9). Due to the low conductivity of such a buffer (0.7 mmhos), separations can be carried out at 800 V/cm, even in relatively large bore capillaries (50 microm ID), ensuring good sensitivity. The zein patterns thus obtained are species-specific and allow easy identification of all maize lines tested. No adsorption of proteins to the silica wall is observed and high reproducibility in peak areas and transit times is obtained. The relatively slow migration time (ca. 30 min), even under such a high voltage gradient, is attributed to the paucity of basic amino acid residues typical of zeins, leading to an unfavorable charge/ mass ratio due to the modest net positive charge at the operative pH.

Inhibin binding sites in bovine pituitary membranes

Membranes derived from bovine pituitary glands free of the neural lobe were used to investigate the presence of binding sites for inhibin, a glycoprotein produced by the ovarian granulosa cells capable of selectively suppressing FSH secretion from the pituitary gland. Optimal concentration of membranes (400 micrograms prot) and 125I-bovine inhibin (2 nM) were incubated in a medium containing 50 mM Tris-HCl pH 7.4, 0.01 M MgCl2 and BSA 0.01% in a final assay volume of 200 microliters at 37 degrees C for different time intervals. Non-specific binding was estimated using unlabelled inhibin in excess. The time course of specific 125I-bovine inhibin (2 nM) binding to bovine pituitary membranes is slow with 50% binding at approximately 20 min of incubation and reaching equilibrium at 90 min of incubation. The kinetic analysis shows an apparent pseudo first order association rate constant (Kob) equivalent to 4 x 10(-2) min-1. Following equilibrium with the tracer, a large excess of unlabelled inhibin (1.27 microM) was able to displace 84% of the specific binding within 120 min of incubation and 50% of the binding at approximately 40 min. The analysis under displacing conditions showed an apparent dissociation rate constant (K2) equals to 1.5 x 10(-2) min-1 and an apparent association rate constant (K1) equals to 1.3 x 10(9) M min-1. Thus, the estimation of the apparent kinetic equilibrium dissociation constant (Kd = K2/K2) of the binding of inhibin to bovine pituitary membranes was 1.2 nM. These results show for the first time the existence of bovine inhibin specific binding sites in bovine pituitary, and also that such a binding can take place in the absence of either gonadal and/or hypothalamic influences. They also contribute to the better understanding of the role of non-steroidal hormones such as inhibin, in the regulation of gonadotrophin secretion.

[Human intestinal parasites in Subsaharan Africa. I. Eastern Boè and Canhabaque Island (Guinea-Bissau)]

A coprological survey was carried out in 1982-1983 in East Boè and in Canhabaque Island, (Bijagòs Islands), where 289 and 288 specimens of stools, respectively, have been collected. The samples were taken from apparently healthy subjects, of both sexes and of different age groups. The tests were made according to the modified Ritchie technique. The following results were obtained: A) East Boè: 1) Protozoa: E. coli 68.9%, E. nana 24.6%, G. intestinalis 8.7%, I. buetschlii 5.9%, E. histolytica 1.7%, E. hartmanni 0.7%, T. intestinalis 0.7%. b) Helminths: Ancylostomatidae 69.2%, T. trichiura 38.4%, S. stercoralis 6.2%, Taenia sp. 1.7%, H. nana 0.7%, S. haematobium 0.7%, S. mansoni 0.7%, S. fuelleborni 0.7%. B) Canhabaque: a) Protozoa: E. coli 85.1%, I. buetschlii 14.9%, E. nana 12.5%, G. intestinalis 8.3%, C. mesnili 7.3%, E. hartmanni 1.4%, E. histolytica 1.0%, T. intestinalis 0.4%. b) Helminths: Ancylostomatidae 87.9%, T. trichiura 9.4%, S. stercoralis 7.9%, S. fuelleborni 2.8%, Trichostrongylus sp. 1.4%, A. lumbricoides 0.7%, H. nana 0.4%. Eggs of Capillaria sp. probably pseudoparasites, were found in 8.7% of samples. The high prevalence of Ancylostomatidae infections appears to be related to the heavy fecal pollution all over the examined territory. The utilization of antihelminthic drug of popular medicine, which has a specific action on A. lumbricoides, could explain the lack and the low prevalence, respectively, of A. lumbricoides infections in both examined areas. In the past, other authors emphasized the low prevalence of this parasite for other Guinea Bissau regions which have a different geomorfological constitution. The cases of S. fuelleborni and H. nana are the first reported for Guinea Bissau.