The effect of structural parameters and positive charge distance on the interaction free energy of antimicrobial peptides with membrane surface

Many attempts have been made to find hints explaining the relationship between physicochemical and structural properties of antimicrobial peptides (AMPs) which are relevant to their antimicrobial activities. We here found that there is a difference in the percentages of hydrophobic, hydrophilic, and charged residues between AMPs killing both bacteria and fungi (Group A) and AMPs that only kill bacteria (Group B). The percentage of charged residues in Group A AMPs is highly elevated, while in Group B the percentage of hydrophobic residues is increased. This result suggests a sequence-based mechanism of selectivity for AMPs. Moreover, we examined how the distance between basic residues affects the interaction free energy of AMPs with the membrane surface, since most of the known AMPs act by membrane perturbation. We measured the average distance between basic residues throughout the 3D structure of AMPs by defining D_pr parameter and calculated the interaction free energy for 10 AMPs that interacted with the DPPC membrane using molecular dynamics simulation. We found that the changes of the interaction free energy correlates with the change of D_pr by a linear regression coefficient of r^2?=?.47 and a cubic regression coefficient of r^2?=?.70.     

Receptor specificity,functional characteristics,and cell-surface phenotype of a highly selected anti-I-Ab-specific,long-term T-cell line

A highly selected alloreactive T-cell line was developed by repeated restimulation of B10.D2/n lymph-node cells with irradiated C57BL/10Sn (BIO) spleen cells in long-term MLC for up to 2 1/2 years. Continuous growth of the line requires restimulation every 2 to 4 weeks with fresh H-2^b stimulator cells. The line proliferates strongly against H-2^b but not againstH-2 ^d ,H-2 ^f ,H-2 ^q ,H-2 ^r , orH-2 ^s stimulators. Analysis of recombinant mouse strains showed that the proliferative response is directed against I-A^b but not K^b or D^b determinants. During the growth period of the line, strong cross-reactivity with H-2^p (B10.P) and weak cross-reactivity with H-2^k strains (e.g., CBA/J and B10.BR) was observed. A clone with exquisite specificity for I-A^b, but with no cross-reactivity with H-2^p or H-2^k was isolated from the line; thus clonal heterogeneity of the line still exists despite the highly selective growth conditions. — The majority of T cells from the line or clone were shown to bind I-A^b but not K^b or D^b determinants either spontaneously during restimulation with fresh B10 stimulator cells or via membrane vesicles expressing I-A^b determinants. No killing activity by the line in either specific or nonspecific cytolytic T-cell assays was observed nor was the T 145 glycoprotein, characteristic of killer T cells, detected.Abbreviations used in this paper B6 C57BL/6J - B10 C57BL/10Sn - Con A Concanavalin A - CTL cytotoxic T lymphocyte - FCS fetal calf serum - FDA fluorescein diacetate - FITC fluorescein isothiocyanate - Ia I-region-associated antigens - LPS lipopolysaccharide fromE. coli - Lyt T-lymphocyte-defined antigen - MLC mixed leukocyte culture - NP-40 nonidet P-40 - PAGE pofyacrylamide gel electrophoresis - PHA phytohemagglutinin fromPhaseolus vulgaris - PM plasma membrane - SDS sodium dodecyl sulfate - TCGF T-cell growth factor(s) - TdR thymidine     

Comparative Resistance of Strains of Clostridium botulinum to Gamma Rays

A total of 102 strains of Clostridium botulinum (56 strains of type A, 43 type B, and 3 nontoxigenic strains which could not be typed) was examined for resistance to gamma rays. When these organisms were suspended in neutral phosphate buffer in concentrations of 10⁴ spores per tube, the threshold sterilizing dose appeared to be 1.4 Mrad. Partial survival to 1.4 Mrad was shown by 10.7% of the type A strains, 18.6% of the type B strains, and one of three nontoxigenic strains. Over-all, type A strains indicated higher radioresistance than type B strains, although there was overlapping. Representatives of the most resistant strains had D values of 0.317 to 0.336 Mrad; the D values of an intermediate group were 0.224 to 0.253 Mrad, and the most sensitive strain studied, 51B, had a D value of 0.129 Mrad. The radioresistance of Putrefactive Anaerobe 3679, strain S-2, was comparable to the intermediate C. botulinum group (D = 0.209).     

Proximity of the Mep-1 Gene to H-2D on chromosome 17 in mice

The Mep-1 gene on chromosome 17 in mice controls the activity of meprin, a kidney brush border metalloendopeptidase. Most inbred mouse strains of the k haplotype (e.g., CBA, C3H, AKR) are markedly deficient in meprin activity; these mice carry the Mep-1 ^ballele. Mouse strains in which meprin activity levels are normal are designated Mep-1 ^a Studies using congenic and recombinant strains mapped the Mep-1 gene telomeric to H-2D near the Tla gene. To further study the relationship between the major histocompatibility complex and Mep-1, a linkage study was conducted. Mep-1 ^a F₁ hybrids [C3H.A (K ^k D ^d ) × C3H.OH (K ^d D ^k )] were backcrossed with Mep-1 ^b C3H.OH (K ^d D ^k ) parents. The progeny were assayed for H-2D markers, Pgk-2 isozymes, and meprin activity. Recombination between H-2D and Mep-1 occurred in 6 out of 284 mice, a crossover frequency of 2.1%. Mep-1 is therefore 2.1 crossover units telomeric to H-2D and approximately 0.6 crossover units from Tla. The Mep-1 locus provides a new genetic marker for the future mapping of this important area of the mouse genome.     

Radiation Sterilization of Bacon for Military Feeding

Sliced, cured bacon, packed in cans and seeded with 6 × 10⁵ spores per can of Clostridium botulinum strains 33A or 41B, or with 3 × 10⁶ spores per can of strains 36A, 12885A, 9B, or 53B, was irradiated to various dose levels with γ radiation. Evidence provided by swelling, toxicity, and recoverable C. botulinum with 2,200 inoculated, irradiated cans demonstrated that: (i) 4.5 Mrad were more than adequate as a sterilization dose; (ii) the experimental minimal sterilizing dose was 2.0 Mrad, and the theoretical 12-log reduction dose was 2.65 or 2.87 Mrad depending on the method of calculation; (iii) some spoilage occurred at dose levels below 2.0 Mrad; (iv) all visible spoilage of irradiated bacon was due to strains 33A and 12885A only, whose D values were, respectively, 0.141 and 0.177 Mrad based on spoilage data, and 0.221 and 0.188 Mrad, respectively, when based on recovery data; (v) toxic cans did not always result in swelling, nor did swollen cans always produce toxic spoilage; and (vi) viable C. botulinum can exist for at least 8 months in storage at 30 C without producing visible or toxic spoilage at doses below 2.0 Mrad.     

Interacting genetic factors controlling the antibody response against the H-2.2 specificity

The antibody response against the H-2.2 specificity has been studied in three H-2 ^d strains, B10.D2, DBA/2, and BALB/c, and their hybrids (B10.D2 × DBA/2)F₁ and (B10.D2 × BALB/c)F₁. The genetic control of the response appears to be complex: The three pure strains are responders, whereas both hybrids when immunized with C3H-HTG are nonresponders. Individual analysis of N3 offspring is compatible with the idea that, in this combination, an Ea-4 incompatibility between donor and immunized strain is necessary for the anti-H-2.2 response to occur. H-2 ^d /H-2 ^k hybrids (B10.BR × B10.D2)F₁ or (B10.BR × DBA/2)F₁ are responders when immunized with C57BL/10 (H-2 ^b ) but not with B10.A(2R) (H-2 ^h ), indicating that simultaneously recognized H-2 specificities are necessary for the anti-H-2.2 response.     

Serological and complementation studies in four C57BL/6H-2 mutants

C57BL/6 (H-2 ^b ) mice, and four mutants (B6.C-H-2 ^ba , B6-H-2 ^bg1 , B6-H-2 ^bg2 , B6-H-2 ^bh ) derived from this strain after separate mutations had occurred at the same locus within theH-2 complex, were analyzed to determine whether the mutations had led to anyH-2 (or Ia) difference which could be detected serologically. The strains were typed directly with antisera specific for H-2K and H-2D public and private specificities and for the Ia specificities; quantitative absorption studies were also performed for the relevant H-2K^b, H-2D^d and Ia^b specificities. In no case was any quantitative or qualitative difference detected serologically between any of the strains. In addition, by using a variety of techniques to produce and assay for antibody, we failed to produce any antisera between the parental strains and the four mutants. TheH-2 mutations therefore appear to give rise to a type of antigenic specificity which is recognized byT cells and which generateT, but notB cell responses; nor are they recognized by H-2 or Ia alloantisera. The location of the mutating locus within theH-2 complex was shown by the complementation method to be within theK orIA region and not in theIB region, since crosses of the mutant strains with B10.A(4R) or D2.GD failed to complement for a subsequent C57BL/6 skin graft.     

Photosynthetic rates of citronella and lemongrass

Ten selections of citronella (Cymbopogon nardus [L.] Rendle) were grown at 32/27, 27/21, or 15/10 C day/night temperatures, and plants from three populations of lemongrass (Cymbopogon citratus [D.C.] Stapf from Japan or Sri Lanka and Cymbopogon flexuosus [D.C.] Stapf from India) were grown at 8- or 15-hour photoperiods. Net photosynthetic rates of mature leaves were measured in a controlled environment at 25 C and 260 microeinsteins per meter² per second. Rates declined with increasing leaf age, and from the tip to the base of the leaf blade. Rates for citronella leaves grown at 15/10 C were extremely low for all selections. Highest rates of net photosynthesis were recorded for four selections grown at 27/21 C and for two selections grown at 32/27 C. Lemongrass grown at 8-hour photoperiod had higher photosynthetic rates than that grown at 15-hour photoperiod.     

The role ofH-2 regions in overcoming tissue incompatibility

Neonatal transplantation tolerance to the products of theH-2 ^b complex was induced in B10.A (H-2 ^a ) mice. On the basis of the survival of skin allografts it was found that antigens determined by theD region of theH-2 ^b complex (of the B10.A(2R) strain) were most easily overcome and that tolerance to the products of theD end of theH-2 complex (of the B10.A(4R) strain) was also easy to induce. The antigens produced by theK end ofH-2 (of the B10.A(5R) and B10.A(3R) strains) represented a stronger incompatibility barrier and a difference in the entireH-2 ^b complex caused strongest resistance to tolerance induction. When tolerance to the products of the entireH-2 ^b complex was induced in newborn B10.A mice, and the neonatally treated animals were grafted simultaneously with five different grafts, those disparate at theK end ofH-2 and in the entireH-2 region were rejected in some animals, while the grafts disparate at theD end of H-2 remained intact in the same mice. No dependence on theI-J subregion was observed in this system. Furthermore, tolerance was more easily inducible in male than in female B10.A mice.     

Complex genetic effect of B10.D2 (M504) (H-2dm1) mutation

Serological and capping experiments show that the strain B10.D2 (M504) carrying the mutant haplotypeH-2 ^dm1 has two molecules in the products of theD region: H-2D^dm1 and H-2L^dm1 which are detectable by anti-H-2.4 and by anti-H-2.28 sera, respectively. Both these molecules differ serologically from the H-2D^d and H-2L^d molecules of the original (nonmutant) strain B10.D2. A third molecule, different from H-2D and H-2L, was detected inH-2 ^d ,H-2 ^dm2 but not inH-2 ^dm1 products.     

A third class I major histocompatibility complex antigen encoded by a gene in the D region of the H-2 d haplotype recognized by cytotoxic T lymphocytes

The D region of the H-2 ^d haplotype contains five class I genes: H-2D ^d , D2 ^d , D3 ^d , D4 ^d and H-2L ^d . Although previous studies have suggested the presence of D-end encoded class I molecules in addition to H-2D^d and H-2L^d, segregation of genes encoding such molecules has not been demonstrated. In this report we have used cãtotoxic T lymphocytes (CTL) to examine the D region of the H-2 ^d haplotype for the presence of additional class I molecules. CTL generated in (C3H × B6.K1)F₁ (K ^k D ^k , K ^b D ^b ) mice against the hybrid class I gene product Q10^d/L^d expressed on L cells cross-react with H-2L^d but not H-2D^d molecules, as determined by lysis of transfected cells expressing H-2L^d but not H-2D^d. Although H-2L^d-specific monoclonal antibodies (mAb) completely inhibit H-2L^d-specific CTL from killing B10.A(3R) (K ^b D ^d L ^d ) target cells, only partial inhibition of anti-Q10 CTL-mediated lysis was observed, suggesting the presence of an additional D-end molecule as a target for these latter CTL. To identify the region containing the gene encoding the Q10 cross-reactive molecule, we show that anti-Q10 CTL lyse target cells from a D-region recombinant strain B10.RQDB, which has H-2D ^d , D2 ^d , D3 ^d , D4 ^d , and H-2D ^b but not the H-2L ^d H-2 ^d , and H-2L ^d (including D2 ^d , D3 ^d , and D4 ^d , lacks this anti-Q10 CTL target molecule. Together, these data demonstrate that a class I gene mapping between H-2D ^d and H-2L ^d encodes an antigen recognozed by anti-Q10 CTL. A likely candidate for this gene is D2 ^d , D3 ^d or D4 ^d .     

BALB/c-H-2 db : A newH-2 mutant in BALB/cKh that identifies a locus associated with theD region

A newH-2 mutant, BALB/c-H-2 ^db , is described. This mutant originated in BALB/c, is inbred, and is coisogenic with the parental BALB/cKh strain. The mutation is of the loss type since BALB/c-H- ^db rejects BALB/c, but not vice versa. Complementation studies have localized the mutation to theD region of theH-2 complex. A cross between BALB/c-H-2 ^db and B10.D2-H-2 ^da failed to complement for either BALB/c or B10.D2 skin grafts, indicating that these are two separate mutations at the same locus (Z2). Direct serological analysis and absorption studies revealed that, with one exception, theH-2 andIa specificities of BALB/c and BALB/c-H-2 ^db are identical. In particular,H-2.4, the H-2D^d private specificity, is quantitatively and qualitatively identical in the two strains. The exception is that of the specificities detected by antiserum D28b: (k×r)F₁ anti-h, which contains anti-H-2.27, 28, and 29. These specificities appear to be absent from theH-2 ^db mutant since they are not detected directly or by absorption. Other public specificities are present in normal amounts,e.g., the reaction with antisera to H-2.3, 8, 13, 35, and 36. The reaction with antiserum D28 (f×k)F₁ anti-s, which contains antibodies to H-2.28, 36, and 42, is the same in both strains. Antiserum made between the two strains (H-2 ^db anti-H-2 ^d ) reacts like an anti-H-2 serum, in that it reacts with both T and B cells by cytotoxicity, but is not a hemagglutinating antibody. The serum reacts as does the D28b serum in both strain distribution and in cross-absorption studies. We conclude that theH-2 ^db mutation occurred at a locus in theD region, resulting in the loss of the H-2.28 public serological specificity and of a histocompatibility antigen. Whether these are one and the same antigen is not yet known. The data, in view of other evidence, imply that the public and private specificities are coded for by separate genes.Abbreviations used in this paper are as follows CML cell-mediated lysis - MLR mixed lymphocyte reaction - GVHR graft-versus-host reaction - RFC rosette-forming cells - RAM-Ig rabbit anti-mouse IgG     

A Conjugative Transfer System for the Rumen Bacterium, Butyrivibrio fibrisolvens, Based on Tn916-Mediated Transfer of the Staphylococcus aureus Plasmid pUB110

A limitation of genetic studies of the rumen bacterium, Butyrivibrio fibrisolvens, has been the availability of suitable vectors and transfer systems. Using the conjugative tetracycline resistant transposon, Tn916, the Staphylococcus aureus plasmid, pUB110, and the pUB110-based shuttle vector, pUBLRS, a conjugative transfer system was developed for B. fibrisolvens. B. fibrisolvens donor strains H17c2 and H17c12, containing Tn916 and pUB110 or pUBLRS, respectively, were used in mating experiments with selected B. fibrisolvens strains. Kanamycin resistant transconjugants, containing pUB110, of strains 193, 194, and 195 were detected at a combined average frequency of 7.78 × 10^-7 per donor and 1.11 × 10^-5 per recipient. Transconjugants of strains 193 and 194, containing pUBLRS, were detected at an average frequency of 1.22 × 10^-6 per donor and 4.70 × 10^-8 per recipient. Southern hybridization analysis confirmed the presence of pUB110 and pUBLRS in transconjugants. Results indicated that Tn916 was necessary for mobilization of pUB110 as transconjugants were not detected when the transposon was absent from the donor strains. The ability to mobilize pUB110 and pUBLRS between B. fibrisolvens strains provides a conjugative transfer system that circumvents problems encountered with electroporation.     

H-2-linked control of resistance to Ectromelia virus infection in 1310 congenic mice

Several B 10 strains of mice, recombinant at theH-2 locus, have been shown to differ in their resistance to infection with ectromelia virus, a natural mouse pathogen. Of 10 strains, 1310, B 10.A(2R), B10.A(4R) and B10.D2 were the most resistant, while B10.G and B 10.A(5R) were the most susceptible. Other strains were intermediate between these extremes. Several genes conferring resistance have been mapped toD ^b in B10.A(2R),K ^k I-A ^k I-B ^k in B10.A,I-J ^b in B10.A(2R) and toD ^d in B 10.T(6R). In general, death among susceptible strains was not a consequence of acute liver necrosis as in other non-B10 strains, and occurred randomly from 8–14 days after infection. The exact cause of death is unknown but is characterized by persisting high titers of virus in the spleen and sometimes the liver, despite an ongoing immune response indicated by strong cytotoxic T-cell activity detectable in the spleens of all mice. The most resistant B10 and B10.A(2R) strains cleared virus from the spleen and liver by 8 days after infection. Analysis of infection in chimeric mice indicates thatH-2 genes, which determine susceptibility to virus persistence in the spleen, operate via radiosensitive cells of the lymphomyeloid system. This evidence, together with several examples ofH-2-linked differences in cytotoxic T-cell responsiveness between resistant and susceptible strains, is consistent with the hypothesis that the mechanism by whichH-2 genes control resistance to ectromelia virus in B10 strain mice is by their influence on the effectiveness of a cell-mediated immune response.     

Effect of different K+ concentrations on cryptococcus neoformans phenoloxidase activity

Melanin synthesis in Cryptococcus neoformans, catalyzed by phenoloxidase activity, is one of the oldest virulence factors known. However, until now, the relationship between melanin production in C. neoformans and its virulence has been poorly understood. Among different chemical compounds only Fe³⁺ and Cu²⁺ cations enhance the phenoloxidase activity in C. neoformans. A few reports in the literature describe the influence of different cations on C. neoformans phenoloxidase activity, excluding iron [1–3]. In this study, 13 C. neoformans strains isolated from AIDS patients and 7 from bird droppings (B.D.), were examined in order to clarify the effect of different K⁺ concentrations on phenoloxidase activity. A new solid and liquid caffeic acid minimal synthetic medium (MSM-CAF) containing only caffeic acid and ferric citrate with different potassium concentrations was used to evaluate C. neoformans phenoloxidase activity. In the MSM-CAF solid medium the degree of brown pigmentation on the agar plates was read on days 1, 2 and 3 of incubation, and the pigmentation of the C. neoformans strains was classed into 5 categories. The brown pigment of the liquid MSM-CAF test tubes were checked after 24 hours of incubation by measuring the optical density (O.D.) at 480 nm. Three C. neoformans AIDS and B.D. strains, randomlychosen, were tested for phenoloxidase activity, according to the modified protocols of Polachecket al., Torres-Guerrero et al. and Rhodes [2–4]. According to the results obtained, it has been observed that K⁺ does not activate the phenoloxidase activity in the C. neoformans AIDS and B.D. strains. In particular, with an increase in potassium concentrations in the MSM-CAF solid and liquid medium, there was a corresponding inhibition of the phenoloxidase activity on both the C. neoformans AIDS and B.D. strains.This revised version was published online in October 2005 with corrections to the Cover Date.     

Immunogenetic analysis ofH-2 mutations

A.BY, B10.LPa, and B10.129(5M) mice were presensitized in vivo against B10.A(5R) cells and then restimulated in vitro by the same cells in the standard CML assay. The effector cells thus generated lysed not only B10.A(5R), but also C57BL/6 targets, indicating that, in addition to anti-H-2D_d response [measured on the B10.A(5R) targets], response to minor histocompatibility (H) antigens (measured on the C57BL/6 targets) also occurred. The latter response was directed against multiple minor H antigens in the case of the A.BY effectors, and against H-1 and H-3 antigens in the case of B10.129(5M) and B10.LPa effectors, respectively. The sensitization against minor H antigens occurred in the context of H-2K^b H-2D^d antigens, but by testing the response on C57BL/6 targets, only cells reacting with minor H antigens in the context of H-2K^b were assayed. The same effector cells were then tested against H-2^b mutant strains, in which theH-2K ^b allele was replaced by a mutant one. All three effector types [A.BY, B10.LPa, and B10.129(5M)] behaved in a similar way: they all reacted with theH-2 ^bg1 mutant to the same degree as withH-2 ^b, they did not react at all or reacted only weakly with theH-2 ^bd andH-2 ^bh mutants, and they reacted moderately or strongly with theH-2 ^ba mutant. The degree of crossreactivity with the mutants reflects, with one exception, the degree of relatedness of these mutants toH-2 ^b, as established by other methods. The one exception is theH-2 ^ba mutant, which is the most unrelated toH-2 ^b, and yet it crossreacted strongly. Further testing, however, suggested that in this instance the crossreactivity was probably directed against H-2 antigens: the anti-H-2D^d effectors apparently crossreacted with the H-2K^ba antigens. This finding is an example of cell-mediated crossreactivity between the products of two differentH-2 genes (H-2K andH-2D). It is also an example of anH-2 mutation generating an antigenic determinant known to be present in another strain.     

<Emphasis Type="Italic">Escherichia coli</Emphasis> phylogenetic group determination and its application in the identification of the major animal source of fecal contamination

Background  

Escherichia coli strains are commonly found in the gut microflora of warm-blooded animals. These strains can be assigned to one of the four main phylogenetic groups, A, B1, B2 and D, which can be divided into seven subgroups (A₀, A₁, B1, B2₂, B2₃, D₁ and D₂), according to the combination of the three genetic markers chuA, yjaA and DNA fragment TspE4.C2. Distinct studies have demonstrated that these phylo-groups differ in the presence of virulence factors, ecological niches and life-history. Therefore, the aim of this work was to analyze the distribution of these E. coli phylo-groups in 94 human strains, 13 chicken strains, 50 cow strains, 16 goat strains, 39 pig strains and 29 sheep strains and to verify the potential of this analysis to investigate the source of fecal contamination.     

The effect of probiotic BioPlus 2B on feed efficiency and metabolic parameters in swine

The purpose of our work was to observe the influence of probiotic preparation BioPlus 2B on average daily gains of weaned pigs, feed efficiency and to evaluate some metabolic indices. The weaned pigs, at the age of 42 days, were included into the trial and divided into four groups. Pigs in groups A (n = 5) and B (n = 4) received BioPlus 2B also before weaning. Only group A received BioPlus 2B, at the concentration of 3.2 × 10⁹ CFU per kg of feed, after weaning continually. Groups C (n = 5) and D (n = 4) did not receive BioPlus 2B until the start of the trial, but group C was given BioPlus 2B at the same concentration as group A during the experiment. Blood samples for determination of metabolic indices were collected at the start of experiment, i.e. on 42^nd day of pigs life, and then on 56^th, 70^th, 84^th and 91^st days of pigs life. The following biochemical indices were evaluated within the trial: serum levels of total proteins, albumin, urea, total cholesterol and total lipids. Total serum protein level (p < 0.0001) and serum albumin level (p = 0.0024) in groups A and B were significantly higher in comparison with groups C and D on day 56 of pigs life. Serum urea level in group D was significantly (p = 0.049) higher than in group A on 70^th day of pigs life. Serum level of total cholesterol in group B on day 56 and 84 of pigs life was significantly (p = 0.0004) higher than in groups C and D. Total serum lipid level was significantly (p < 0.05) higher in B group compared to other groups on 56^th, 70^th, 84^th days of pigs life. Average daily gains (ADG) in A group, even if non-significantly, were about 10% better than in groups B, C, D between 57^th and 77^th days of pigs life. ADG in groups A and B were 14% better in comparison with that in groups C and D between 78^th and 91^st days of pigs life (p = 0.036). The best feed efficiency in the trial was in group A, approximately 13%, 16% and 21% better than that in the groups B, C and D, repectively. Presented at the Second Probiotic Conference, Košice, 15–19 September 2004, Slovakia.     

Hemoglobins, haptoglobins, and transferrins in indigenous populations of Kenya

Hemoglobin, haptoglobin, and transferrin phenotypes were determined by means of starch-gel electrophoresis for a sample of 226 Kenya hospital patients. Allele frequencies were: Hb_β^S=0.081; Hp¹=0.057; Tf^D=0.038. Hemoglobin S was the only aberrant hemoglobin found in this sample. Transferrins C and D were the only transferrins found. Hemoglobin and transferrin phenotypes were also determined for a sample of 201 newborn Kenya infants. One of these infants had hemoglobins F, S, and C, eight had hemoglobins A, F, and S, and the remainder had hemoglobins A and F. Transferrins C, B, and D were found in this sample. Allele frequencies were: Tf^B=0.008; Tf^D=0.019.     

Composition and Chemical Variability of Enantia polycarpa Engl. & Diels Leaf Essential Oil from Côte d'Ivoire

The composition of Enantia polycarpa Engl . & Diels leaf essential oil has been investigated for the first time using a combination of chromatographic and spectroscopic techniques. The compositions of 52 leaf essential oil samples have been subjected to statistical analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA). Four groups were differentiated, of which the compositions were dominated by β‐elemene and germacrene B (Group III, 22/52 samples); germacrene D (Group I, 16/52 samples); β‐cubebene (Group IV, 8/52 samples) and by germacrene B and germacrene D (Group II, 6/52 samples). A special attention was brought to the quantification of the thermolabile components, germacrene A, germacrene B and germacrene C, as well as that of their rearranged compounds, β‐elemene, γ‐elemene and δ‐elemene. ¹³C‐NMR data of β‐cubebene have been provided.