In vitro and in vivo toxicity evaluation of plant virus nanocarriers

The use of biological self-assembling materials, plant virus nanoparticles in particular, appears very intriguing as it allows a great choice of symmetries and dimensions, easy chemical and biological engineering of both surface and/or internal cavity as well as safe and rapid production in plants. In this perspective, we present an initial evaluation of the safety profile of two structurally different plant viruses produced in Nicotiana benthamiana L. plants: the filamentous Potato virus X and the icosahedral Tomato bushy stunt virus. In vitro haemolysis assay was used to test the cytotoxic effects, which could arise by pVNPs interaction with cellular membranes, while early embryo assay was used to evaluate toxicity and teratogenicity in vivo. Data indicates that these structurally robust particles, still able to infect plants after incubation in serum up to 24h, have neither toxic nor teratogenic effects in vitro and in vivo. This work represents the first safety-focused characterization of pVNPs in view of their possible use as drug delivery carriers.

Erythroid carbonic anhydrases of developing chick embryos. Coordinate expression with primitive and definitive embryonic haemoglobins

Erythroid carbonic anhydrase activity of chick embryos from the 3rd day of incubation to the egg hatching has been determined. Three minor activity peaks at 3, 9 and 15 days of development and a major one at 19 days were found. The enzyme molecular forms were purified by affinity chromatography from haemolysates of embryos at several stages of development. As has been found for the adult erythrocytes, only type II isozyme was detected in the embryo red cells. Isoelectrofocusing analysis demonstrated that two different molecular forms of this isozyme are synthesized by the red cells of developing embryos. Only the early form is present up to 5 days of development; the late form, which is indistinguishable from the adult isozyme, appears in the haemolysate at 6-7 days and quickly replaces the early form. Analysis of purified primitive and definitive erythroid lines from 7-days-old embryos showed a compartmentalization of the early and late forms into the primitive and definitive erythroid cells, respectively.

Koelliker haemoglobins in developing chick embryo

1. Three Koelliker haemoglobins, HbKE, HbKA and HbKH, derived from a post-translational loss of alpha-Arg-141, were isolated from red cells of chicken embryos. HbKE is typical of embryos up to 7 days of incubation, HbKA and HbKH are found in mature embryos. 2. All the precursor haemoglobins contain alpha A chains. HbKA derives from adult haemoglobin A whose globin composition is alpha A2 beta 2, HbKH from embryonic haemoglobin H with a globin composition alpha A2 beta H2 and HbKE from embryonic haemoglobin E with globin composition alpha A2 epsilon 2. 3. No Koelliker derivatives of haemoglobins with alpha-like chains other than alpha A were observed.

Chick embryo survival under acute carbon monoxide challenges

1. Early chick embryos (up to 7 days) survive longer in 1% CO than older ones. As shown by the partition constants of the oxygen-carbon monoxide equilibrium, such a behavior cannot be related to the different hemoglobin patrimonies. 2. In vivo, early embryo hemoglobin is completely turned into its CO derivative within about 15 min according to a step-wise progression which reflects the peculiar embryonic pathway of the blood circulation. 3. Diffusing oxygen is sufficient to keep early embryos alive for a long time. 4. Before the chorioallantois is formed, the vascular area acts as the embryonic respiratory organ.

How do avian embryos breathe? Oxygen transport in the blood of early chick embryos

1. Chick embryos with primary circulation, up to about 3 days of development, show no hemoglobin-mediated transport of oxygen. 2. In embryos with secondary circulation, between 3 and 6 days of incubation, the vascular area acts as the respiratory organ. Its efficiency in the oxygen uptake is less than that of the chorioallantois of later embryos. On the contrary, oxygen release to the tissues is highly efficient. 3. A full efficient hematic uptake of oxygen is reached at about the 6th incubation day, when chorioallantois acts as the embryonic respiratory organ. 4. The different respiratory mechanisms of developing chick embryo are closely related to the functional properties of the various hemoglobins which are produced during the embryonic life.

The minor haemoglobins of primitive and definitive erythrocytes of the chicken embryo. Evidence for haemoglobin L

A new minor haemoglobin, L, was isolated from the haemolysates of chicken embryos more than 7 days old. Electrophoresis in denaturing conditions and tryptic peptide maps of the globins show that the beta-like globin of HbL is identical to that of the minor haemoglobin H(beta H) while the alpha-like globin is very similar to that of the adult haemoglobin D (alpha D). HbL completes the description of the map of the minor chicken haemoglobins during embryonic development. In early embryos two minor haemoglobins, M and E, are produced which have the same beta-like globin (epsilon) and differ in their alpha-like globins (alpha D and alpha A, respectively). The same two alpha-like globins will make up the minor haemoglobins of the late embryo, L and H, which differ from HbM and HbE on account of their beta-like globin (beta H). The native tetramers L and M are hard to distinguish from each other. However the constituent epsilon globin can be easily separated from beta H by electrophoresis on polyacrylamide gel in formic acid. With this method we found that the switch of the minor haemoglobins in the blood of chicken embryos starts at the 7th incubation day. The two red cell populations, primitive and definitive, present in the blood of 7-day-old embryos were separated on an albumin gradient and their minor haemoglobins analysed. The haemoglobin couple M/E was found in the primitive erythroid cells whereas the L/H couple was found in the definitive ones. The disappearance of the early haemoglobin couple and its substitution by the late one during embryonic development correlates with the replacement of erythroid lines in the blood.

Evidences that hemoglobin switch in the chick embryo depends on erythroid cell line substitution

Chemical identifications of various hemoglobin types were performed on unfractionated erythroid cells derived from chicken embryos at 5 and 7 days of development and on purified primitive and definitive cells. Proteins were pulse-labelled in primitive erythroid cells at various times of culture to identify those actually synthesized. The data show that primitive cells contain and synthesize only embryonic hemoglobins at all stages of maturation and definitive cells contain adult and minor embryonic hemoglobins, but no major embryonic hemoglobins, not even in trace amounts. These results support a model for hemoglobin switch in the chicken embryo based on cell line substitution.

A Koelliker hemoglobin in chick erythrocytes

1. Adult chicken hemoglobins were analysed by ion exchange chromatography and isoelectric focusing and a minor hemoglobin fraction (HbK) was isolated. 2. Analysis of the constituent chains shows that HbK differs from the two major hemoglobins HbA and HbD in the alpha globin. 3. The amino acid composition, the tryptic peptide maps, the results of carboxypeptidase digestion and the functional properties show that the HbK alpha globin is quite similar to that of HbA except that the C-terminal amino acid Arg 141 is lacking. 4. HbK must then be considered a Koelliker-type hemoglobin.

Improved column-chromatographic isolation of glycosylated hemoglobin S

We investigated glycosylated hemoglobin S by means of chromatography on Bio-Rex 70. The selected elution conditions were similar to those described by Trivelli et al. (N Engl J Med 284: 353-357, 1971), except for modified ionic strength and accurate temperature control. This enabled us to isolate a minor hemoglobin fraction whose properties, as determined by chromatography, electrophoresis, and two-dimensional maps of its tryptic peptides, were typical of a hemoglobin S tetramer with blocked N-terminal residues of the beta subunits. The colorimetric test indicated this to be a glycosylated hemoglobin. This procedure is notably improved over previous chromatographic techniques for isolating glycosylated hemoglobin S. Moreover, it can be easily used in any laboratories where Trivelli's method is routinely in use.

Improved column-chromatographic isolation of glycosylated hemoglobin S

We investigated glycosylated hemoglobin S by means of chromatography on Bio-Rex 70. The selected elution conditions were similar to those described by Trivelli et al. (N Engl J Med 284: 353-357, 1971), except for modified ionic strength and accurate temperature control. This enabled us to isolate a minor hemoglobin fraction whose properties, as determined by chromatography, electrophoresis, and two-dimensional maps of its tryptic peptides, were typical of a hemoglobin S tetramer with blocked N-terminal residues of the beta subunits. The colorimetric test indicated this to be a glycosylated hemoglobin. This procedure is notably improved over previous chromatographic techniques for isolating glycosylated hemoglobin S. Moreover, it can be easily used in any laboratories where Trivelli's method is routinely in use.

Synthesis of globin chains in the erythropoietic sites of the early chick embryo

The synthesis of globins in the chick embryo before the onset of circulation has been studied in situ by specific immunofluorescence labelling of embryonic sections and by labelling newly synthesized proteins in ovo and in vitro in embryonic explants with [3H]leucine.

The presence of major primitive haemoglobins is observed by 28 h of incubation. The minor primitive haemoglobins become detectable by immunofluorescence after 40 h of development, shortly before the onset of circulation. 3H-labelling shows that one definitive α chain is synthesized, though in low concentration, from the initial globin detection. The other definitive α chain is observed in embryos of at least 40 h of development. The relative concentration of the two definitive α chains changes rapidly with development indicating a specific mechanism of regulation.

An erythropoietic site is observed in the wall of the dorsal aorta in embryos of about 45–50 h of development. From the initial detection, those cells contain all four primitive embryonic haemoglobins, in contrast to what is observed for the cells of the blood islands.

Synthesis of globin chains in the erythropoietic sites of the early chick embryo

The synthesis of globins in the chick embryo before the onset of circulation has been studied in situ by specific immunofluorescence labelling of embryonic sections and by labelling newly synthesized proteins in ovo and in vitro in embryonic explants with [3H]leucine. The presence of major primitive haemoglobins is observed by 28 h of incubation. The minor primitive haemoglobins become detectable by immunofluorescence after 40 h of development, shortly before the onset of circulation. 3H-labelling shows that one definitive alpha chain is synthesized, though in low concentration, from the initial globin detection. The other definitive alpha chain is observed in embryos of at least 40 h of development. The relative concentration of the two definitive alpha chains changes rapidly with development indicating a specific mechanism of regulation. An erythropoietic site is observed in the wall of the dorsal aorta in embryos of about 45-50 h of development. From the initial detection, those cells contain all four primitive embryonic haemoglobins, in contrast to what is observed for the cells of the blood islands.

The haemoglobins of developing duck embryos

Three haemoglobins were isolated by ion-exchange chromatography from the haemolysates of embryonic duck erythrocytes up to 8 days of development. The component globins were characterized both by electrophoresis in dissociating conditions and by finger-printing analysis. The major haemoglobin fraction E1 appears to be an embryonic tetramer since its constituent globins are different from all the others synthesized during embryonic and adult life. The two minor fractions E2 and E3 show α-type subunits that are very similar to those of the two adult haemoglobins A1 and A2 respectively. They are present all through embryonic life, as demonstrated by chromatographic analysis. For these reasons they have been considered foetal.

The two haemoglobins typical of the adult animal are found in the red cells of the embryo from 8 days of incubation. Their relative amounts change continuously during embryonic development and reach the adult value after hatching.

The haemoglobins of developing duck embryos

Three haemoglobins were isolated by ion-exchange chromatography from the haemolysates of embryonic duck erythrocytes up to 8 days of development. The component globins were characterized both by electrophoresis in dissociating conditions and by finger-printing analysis. The major haemoglobin fraction E1 appears to be an embryonic tetramer since its constituent globins are different from all the others synthesized during embryonic and adult life. The two minor fractions E2 and E3 show alpha-type subunits that are very similar to those of the two adult haemoglobins A1 and A2 respectively. They are present all through embryonic life, as demonstrated by chromatographic analysis. For these reasons they have been considered foetal. The two haemoglobins typical of the adult animal are found in the red cells of the embryo from 8 days of incubation. Their relative amounts change continuously during embryonic development and reach the adult value after hatching.

HbA1 in subjects with abnormal glucose tolerance but normal fasting plasma glucose

HbA1(a+b+c)(HbA1) was determined chromatographically in 107 subjects with normal fasting plasma glucose (FPG) and 112 patients with overt diabetes. Subjects with normal FPG were divided into two groups based on their response to two oral glucose tolerance tests (OGTTs), at an interval of 2 mo. In 40 subjects with normal OGTT (group I), HbA1 ranged from 5.2% to 7.2%, while in 67 subjects with abnormal OGTT (group II), it ranged from 6.3% to 9.6%. HbA1 levels were significantly higher in group II than in group I (7.7 +/- 0.09% versus 6.4 +/- 0.08%, mean +/- SEM, P less than 0.0005), but 14 subjects of group II had HbA1 levels less than 7.2%. No correlation was found between HbA1 and FPG, OGTT peak, and curve area in either group. However, the correlation became significant in all 107 subjects with normal FPG (groups I + II). In patients with overt diabetes, HbA1 ranged from 6.3% to 18% (11.9 +/- 0.22%) and correlated with FPG (r = 0.78, P less than 0.0005). The traditional OGTT seems more sensitive than the HbA1 measurement in detecting subjects with reduced carbohydrate tolerance. HbA1 level, on the other hand, is known to be more specific indicator of structural abnormalities following long-term hyperglycemia. Thus HbA1 determination might be a helpful test along with OGTT to improve both selection and follow-up subjects with true borderline diabetes.

Localization of acid phosphatases in the cell fractions of chick liver

3 molecular forms (P1, P2 and P3) of acid phosphatase (E.C. 3.1.3.2) have been detected in chicken liver homogenate. The different intracellular localization of these molecules has been demonstrated by cellular fractionation and electrophoretic analysis. P1 and P2 phosphatases are both present in the particulate fraction. P3 is present in a pure form in the soluble fraction. The difference between the enzyme molecules present in the particulate fraction and that in the soluble one is confirmed by the different activation-inhibition effect of various ions and substances on the enzymatic activity of subcellular fractions.

Acid and alkaline phosphatase heterogeneity in liver, heart and intestine of the adult chick

The molecular heterogeneity of acid and alkaline phosphatase from chick liver, intestine and heart is demonstrated by polyacrilamide disc gel electrophoresis. Liver and heart show the same number of molecular forms of acid and alkaline phosphatases. In contrast, the intestine homogenate shows electrophoretic bands different in number and in gel position from those of the liver and of the heart.

The hemoglobins of the developing chicken embryos. Fractionation and globin composition of the individual component of total erythrocytes and of a single erythrocyte type

The hemoglobins of the chicken embryo at several stages of development have been isolated in pure form by column chromatography and their relative amounts and globin compositions determined. The analyses on separated primitive and definitive erythrocytes show that the first contain four hemoglobins different from the adult ones. The two major ones at four days, decrease gradually and are no longer detectable from 15 days on. The two minor ones increase up to 6-7 days, then decrease but are still present at hatching. The definitive embryonic erythrocytes contain two hemoglobins identical to the adult ones but their ratios change gradually during development and approach that of the adult hemoglobins at hatching.