Phosphorus deficiency-induced reduction in root hydraulic conductivity in Medicago falcata is associated with ethylene production

Plants grown in phosphorus-deficient solutions often exhibit disruption of water transport due to reduction in root hydraulic conductivity (Lpr) and enhanced ethylene production. To uncover the relationship between the reduction in Lpr and increase in ethylene production, we investigated effect of phosphorus (P) deficiency on ethylene production and Lpr in legume plants of Medicago falcata L. There was an increase in ethylene production and a reduction of Lpr of M. falcata roots when M. falcata seedlings grown in P sufficient solutions (0.5 mM H₂PO₄^2?) were transferred to P-deficient solutions (5 μM H₂PO₄^2?). Antagonists of ethylene biosynthesis, CoCl₂ and aminoethoxyvinylglycine (AVG), abolished the P deficiency-induced ethylene production. Root hydraulic conductivity of M. falcata seedlings grown in P-sufficient solutions was insensitive to CoCl₂ and AVG, while the two chemicals enhanced Lpr for those grown in P-deficient solutions, suggesting that P deficiency-induced decrease in Lpr can be reversed by inhibiting ethylene production. Ethylene precursor 1-amino cyclopropane-1-carboxylic acid (ACC) and ethylene donor ethephon had greater inhibitory effect on Lpr of P-sufficient seedlings than that of P-deficient seedlings. Root hydraulic conductivity of P-sufficient seedlings was more sensitive to HgCl₂ than that of P-deficient seedlings. Taken together, these findings suggest that ethylene induced by P deficiency may play an important role in modulation of root hydraulic conductivity by affecting aquaporins in plants.     

Allelic polymorphism of murine IgE controlled by the seventh immunoglobulin heavy chain allotype locus

Two alloantisera against hybridoma-derived IgE detected allotypic determinants expressed on the murine s chain. An antiserum raised in BALB/c mice against monoclonal IgE of C57BL/6 origin reacted exclusively with IgE of strains having Igh-1^b (IgG_2a) allotype. The second antiserum, C57BL/6 anti-BALB/c monoclonal IgE, reacted with IgE of strains having Igh-1^a, Igh-1^d, Igh-1^e and Igh-1^j allotypes. The genetic studies of (BALB/c x C57BL/6)F₁ and backcross F₂ animals indicated that the locus controlling the IgE allotype is linked to the Igh-1 locus. This was further confirmed by the possession of respective IgE allotypes by Igh-C congenic mice, BALB/c and BAB-14, C3H.SW/Hz and CWB/Hz. Thus, the allotype detected on the chain is controlled by the seventh murine immunoglobulin allotype locus, and should be designated as the Igh-7 allotype.Abbreviations used in this paper PCA passive cutaneous anaphylaxis - RID radioimmunodiffusion - i.p. intraperitoneally - EA egg albumin - Igh-C immunoglobulin heavy chain constant region locus - DNP 2,4-dinitrophenyl - PBS phosphate-buffered saline - NMS normal mouse serum - KLH keyhole limpet hemocyanin Visiting investigator supported by the Scientific and Humanistic Development Council from the Central University of Venezuela, currently at the following address: Consejo de Desarrollo Cientifico y Universidad Central de Venezuela, Av. Principal Urb. La Floresta Ota., Silenia Caracas, Venezuela.     

The IgG2a antibody response to thyroglobulin is linked to the Igh locus in mouse

The IgG-subclass usage by several strains of mice in the response to immunization with mouse thyroglobulin (mTg) was examined in the experimental autoimmune thyroiditis model. While the subclass usage by most mouse strains was similar, the Igh^b allotype-bearing mice consistently produced lower IgG2a levels to mTg. Using CBA-Igh ^b congenic and recombinant inbred strains of mice, the lower level of IgG2a in the Igh^b mouse was mapped to the Igh locus. The regulation of IgG2a appeared to be cis controlled, as the CBA x C57BL/6F₁ mouse also produced reduced IgG2a of the Igh^b (B6) allotype but not Igh^j (CBA) allotype.     

Influence of dhaT mutation of K. pneumoniae on 1,3-propanediol fermentation

Metabolic role of 1,3-propanediol oxidoreductase (PDOR) in the production of 1,3-propanediol (1,3-PDO) with K. pneumonia was investigated by knocking out the coded gene dhaT. Fermentation with both the wide-type and mutant were studied in 5 l fermentor. A PDOR-deficient mutant K. pneumonia T1.9131 with 19% PDOR activity of the wild type was constructed. The cultures of the mutant indicated that PDOR inactivation had great effect on the other dha regulon enzymes: activity of glycerol dehydratase decreased by 70% while activity of glycerol dehydrogenase increased by 68%. Fed-batch fermentation showed that more metabolic flux of glycerol was directed to lactate and ethanol in the mutant. Lactate was identified as major metabolite and received an increase in the final concentration from 45 to 91 g l⁻¹, while the concentration of 1,3-PDO production dropped from 94 to 36 g l⁻¹. The results demonstrated PDOR was not indispensable in glycerol metabolism but was crucial in high 1,3-PDO productivity. It is postulated that a hypothetical oxidoreductase was expressed and replaced the function of PDOR. Blocking the pathway towards lactate and ethanol could be a plausible scheme to enhance 1,3-PDO productivity.     

Regulation of the production of murine IgG2a by an H-2-linked gene and other unlinked genes

Alleles of at least two loci (rig-1 and Rig-2) regulate the levels of serum immunoglobulin of the Igh-1b class and allotype in BALB/c Ig^b (BAB/14) and (BALB/c × BAB/14)F₁ mice. The combined effect of the BALB/c alleles at these two loci is to lower Igh-1b levels significantly below those observed in other strains and below their own levels of Igh-1a in allotype heterozygous mice. The rig-1 locus is closely linked to or within the H-2 complex. Two alleles have been defined: rig-1 ^d and rig-1 ^b in H-2 ^d and H-2 ^b haplotypes, respectively. Homozygous rig-1 ^d d animals heterozygous for the BALB/c Rig-2 allele(s) have very low levels of Igh-1b. The designation of Rig-2 is provisional since it has not been mapped or defined as a single locus.     

Genetics and expression of kappa-type light chains in Basilea rabbits

In contrast to rabbits of b4, b5, b6, and b9 allotypes whose serum immunoglobulins (Igs) are predominantly composed of kappa-type light chains, rabbits of the mutant Basilea strain have serum Igs that are largely of lambda type. We prepared several antisera that recognized a minor K2 (bas) light chain that is produced by Basilea rabbits. With these antisera we identified the K2 (bas) isotype in the serum of the original b ⁹/b ⁹ male rabbit whose offspring displayed the Basilea mutant phenotype. It was present in one half of his nonmutant offspring which inherited b9 from him and another b allotype from their mothers. Breeding was conducted both in Basel and at the NIH to develop and maintain colonies of mutant Basilea strain rabbits. The data obtained during colony development confirm that the trait of expression of the bas allotype maps to the same genetic region (b locus) that is known to control the allelic b allotypes b4, b5, b6 and b9. Homozygotes or heterozygotes of b4, b5 or b6 allotype (b ^b /b ^b ) were mated with homozygous b ^bas /b ^bas rabbits to produce F₁s, and then F₂s as well as progeny of backcrosses to both homozygous parental types (b ^b /b ^b and b ^bas /b ^bas ) were produced. The bas allotype segregates as an allele (or pseudoallele) at the b locus although there was a deficiency in recovery of homozygous bas offspring in both the F₂ and backcross matings to b ^bas /b ^bas parental type in the NIH colony. This selective deficiency may reflect a deleterious effect on survival of homozygous bas progeny.The Basel Institute for Immunology was founded and is supported by F. Hoffmann La-Roche and Co., Ltd., Basel, Switzerland.     

The effect of sodium chloride on the Ca2+, K+ and Na+ concentrations of the seed coat and embryo of Acacia tortilis and A. coriacea

The uptake of Na⁺ and the loss of Ca²⁺ and K⁺ by seeds of Acacia tortilis (Forsk.) Hayne (salt tolerant) and A. coriacea DC. (salt sensitive) were determined after 24 h soaking in 250 mol m^-1,3 NaCl or in distilled water. Na⁺ uptake was higher by the seed coat than by the embryo of both species and higher by A. coriacea than by A. tortilis. The greater Na⁺ uptake by A. coriacea was associated with greater Ca and K⁺ leakage. The Na⁺ concentration of solution imbibed by the embryo of both species was lower than the Na⁺ concentration in the external solution, indicating an exclusion of Na⁺. When A. tortilis and A. coriacea seeds were treated with a series of NaCl concentration (0–400 mol m^-1,3), the exclusion mechanism was particularly clear with A. tortilis at lower concentrations (50 and 150 mol m^-1,3) of NaCl. In contrast, the seed coat of both species accumulated Na⁺. Thus the seed coat may play an important role in ion exchange. These results show that it is important to consider the seed coat and embryo separately rather than the whole seed when considering ion exchange in relation to salinity tolerance.     

MOBILIZATION OF β-1,3-GLUCAN AND BIOSYNTHESIS OF AMINO ACIDS INDUCED BY NH4+ ADDITION TO N-LIMITED CELLS OF THE MARINE DIATOM SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)

Mobilization of the reserve β-1,3-glucan (chrysolaminaran) in N-limited cells of the marine diatom Skeletonema costatum (Grev.) Cleve (Bacillariophyceae) was investigated. The diatom was grown in pH-regulated batch cultures with a 14:10-h light:dark cycle until N depletion. In a pulse-chase experiment, the cells were first incubated in high light (200 μmol photons·m ^{− 2}·s ^{− 1}) with ¹⁴C-bicarbonate until dissolved inorganic carbon was exhausted. Unlabeled bicarbonate (1 mM) was then added, and the cells were incubated in the dark and subsequently in low light (20 μmol photons·m ^{− 2}·s ^{− 1}) with additions of 40 μM NH₄ ⁺ . In the ¹⁴C pulse phase with high light and N depletion, β-1,3-glucan accumulated and accounted for 85% of incorporated ¹⁴C. In the subsequent ¹⁴C chase phases, added NH₄ ⁺ was assimilated at an N-specific rate of 0.11 h ^{− 1} in both the dark and low light, and in both cases it caused a significant mobilization of β-1,3-glucan (dark, 26%; low light, 19%). Biochemical fractionation of organic ¹⁴C showed that free amino acids were most rapidly labeled in the early stage of NH₄ ⁺ assimilation, whereas proteins and polysaccharides were labeled more rapidly after 1.2 h. Analysis of the cellular free amino acids strongly indicated that de novo biosynthesis was occurring, with a Gln:Glu ratio increasing from 0.4 to 10 within 1.2 h. After the NH₄ ⁺ was exhausted, the cellular pools of glucan and amino acids became constant or slowly decreased. In another experiment, N-limited cells were first incubated in high light until dissolved inorganic carbon was exhausted and were further incubated in high light with 150 μM NH₄ ⁺ under inorganic carbon limitation. Added NH₄ ⁺ was assimilated at an N-specific rate of 0.023 h ^{− 1}, and cellular β-1,3-glucan decreased by 15% within 6 h. Hence, β-1,3-glucan was mobilized during NH₄ ⁺ assimilation, even though inorganic carbon was modifying the metabolic rates. The results provide new evidence of β-1,3-glucan supplying essential precursors for biosynthesis of amino acids and other components in S. costatum in both the dark and subsaturating light and even saturating light under inorganic carbon limitation.     

Serological survey of complement factor H in common laboratory and wild mice: a new third allotype

Antigenic specificities of complement factor H from mice were studied serologically. In addition to previously reported allotypes, referred to as H.1 and H.2, a new allotype of complement factor H, H.3, was identified in the BFM/2Ms strain derived from European wild mice. Using three different alloantisera raised against the various mouse factor H allotype, a serological survey of the common laboratory strains and wild-derived strains of Mus musculus and its relatives, Mus spretus, Mus spretoides, and Mus spicilegus was carried out. All of the common laboratory strains examined in this survey had the H.1 allotype except for STR/N which had H.2. The geographical distributions of factor H allotypes in M. musculus were specific to the subspecies. Mice derived from Mus musculus domesticus and Mus musculus castaneus had the H.1 allotype. Mice derived from M. m. musculus, Mus musculus bactrianus, and Mus musculus molossinus had the H.2 allotype. Only BFM/2Ms and BFM/1Mpl strains derived from M. m. domesticus had the novel H.3 allotype. Sera of mice from strains derived from M. spretoides and M. spicilegus cross-reacted with H.2-specific antiserum, and those from M. spretus cross-reacted with H.3-specific antiserum.     

Tests of association of immunoglobulin allotype genes and viral oncogenesis in chickens

Chickens from Regional Poultry Research Laboratory (RPRL) inbred line 6₃ are resistant to virally-induced Marek's disease (MD) and lymphoid leukosis (LL) and are relatively strong regressors of virally-induced Rous sarcomas. In contrast, RPRL line 100 chickens are highly susceptible to MD and LL and are weaker regressors of Rous sarcomas than line 6₃. RPRL lines 100 and 6₃ differ for alleles at the IgG-1 (G-1) allotype locus, but have identical IgM-1 (M-1) allotype alleles. To test the possible association of the G-1 locus with variations in resistance to virally-induced tumors, homozygous and heterozygous genotypes among F₃ crosses were infected. F₃ chickens with different G-1 types were comparable in their resistance to MD tumors following inoculation with the JM strain of the MD virus, and for their ability to regress Rous sarcoma tumors induced by the Rous sarcoma virus (RSV) RAV-1. However, following RAV-1 virus infection a smaller proportion of G-1 ^a /G-1 ^a F₃ or F₄ birds developed LL tumors than G-1 ^a /G-1 ^e and G-1 ^e /G-1 ^e birds. Genes determining immunoglobulin heavy chains were therefore associated with a recessive resistance to B-cell lymphomagenesis in chickens.Deceased     

Increase in Silk Production by the Silkworm,Bombyx morì L., due to Oral Administration of a Juvenile Hormone Analog

(R)-1,3-butanediol ((R)-1,3-BD) is an important substrate for the synthesis of industrial chemicals. Despite its large demand, a bioprocess for the efficient production of 1,3-BD from renewable resources has not been developed. We previously reported the construction of recombinant Escherichia coli that could efficiently produce (R)-1,3-BD from glucose. In this study, the fermentation conditions were optimized to further improve 1,3-BD production by the recombinant strain. A batch fermentation was performed with an optimized overall oxygen transfer coefficient (82.3?h^?1) and pH (5.5); the 1,3-BD concentration reached 98.5?mM after 36?h with high-yield (0.444?mol (mol glucose)^?1) and a high maximum production rate (3.63?mM?h^?1). In addition, a fed-batch fermentation enabled the recombinant strain to produce 174.8?mM 1,3-BD after 96?h cultivation with a yield of 0.372?mol (mol glucose)^?1, a maximum production rate of 3.90?mM?h^?1, and a 98.6% enantiomeric excess (% ee) of (R)-1,3-BD.     

Fermentation of 1,3-propanediol by a lactate deficient mutant of Klebsiella oxytoca under microaerobic conditions

Klebsiella oxytoca M5al is an excellent 1,3-propanediol (1,3-PD) producer, but too much lactic acid yielded greatly lessened the fermentation efficiency for 1,3-PD. To counteract the disadvantage, four lactate deficient mutants were obtained by knocking out the ldhA gene of lactate dehydrogenase (LDH) of K. oxytoca M5al. The LDH activities of the four mutants were from 3.85 to 6.92% of the parental strain. The fed-batch fermentation of 1,3-PD by mutant LDH3, whose LDH activity is the lowest, was studied. The results showed that higher 1,3-PD concentration, productivity, and molar conversion rate from glycerol to 1,3-PD can be gained than those of the wild type strain and no lactic acid is produced under both anaerobic and microaerobic conditions. Sucrose fed during the fermentation increased the conversion and sucrose added at the beginning increased the productivity. In fed-batch fermentation with sucrose as cosubstrate under microaerobic conditions, the 1,3-PD concentration, conversion, and productivity were improved significantly to 83.56 g l⁻¹, 0.62 mol mol⁻¹, and 1.61 g l⁻¹ h⁻¹, respectively. Furthermore, 60.11 g l⁻¹ 2,3-butanediol was also formed as major byproduct in the broth.     

Metabolism in 1,3‐propanediol fed‐batch fermentation by a D‐lactate deficient mutant of Klebsiella pneumoniae

Klebsiella pneumoniae HR526, a new isolated 1,3‐propanediol (1,3‐PD) producer, exhibited great productivity. However, the accumulation of lactate in the late‐exponential phase remained an obstacle of 1,3‐PD industrial scale production. Hereby, mutants lacking D ‐lactate pathway were constructed by knocking out the ldhA gene encoding fermentative D ‐lactate dehydrogenase (LDH) of HR526. The mutant K. pneumoniae LDH526 with the lowest LDH activity was studied in aerobic fed‐batch fermentation. In experiments using pure glycerol as feedstock, the 1,3‐PD concentrations, conversion, and productivity increased from 95.39 g L^?1, 0.48 and 1.98 g L^?1 h^?1 to 102. 06 g L^?1, 0.52 mol mol^?1 and 2.13 g L^?1 h^?1, respectively. The diol (1,3‐PD and 2,3‐butanediol) conversion increased from 0.55 mol mol^?1 to a maximum of 0.65 mol mol^?1. Lactate would not accumulate until 1,3‐PD exceeded 84 g L^?1, and the final lactate concentration decreased dramatically from more than 40 g L^?1 to <3 g L^?1. Enzymic measurements showed LDH activity decreased by 89–98% during fed‐batch fermentation, and other related enzyme activities were not affected. NADH/NAD⁺ enhanced more than 50% in the late‐exponential phase as the D ‐lactate pathway was cut off, which might be the main reason for the change of final metabolites concentrations. The ability to utilize crude glycerol from biodiesel process and great genetic stability demonstrated that K. pnemoniae LDH526 was valuable for 1,3‐PD industrial production. Biotechnol. Bioeng. 2009; 104: 965–972. © 2009 Wiley Periodicals, Inc.     

Immune response to the Slp alloantigen in the mouse:H-2-linked qualitative and quantitative control

Immunization of inbred mouse strains lacking the Slp allotype results in the production of Slp antibodies in some strains but elicits no detectable response in other strains. Analysis of standard inbred and congenic resistant strains reveals that both the qualitative and quantitative ability to respond to the Slp allotype is associated with theH-2 haplotype of the recipient. Three different response phenotypes can be identified utilizing complement fixation and quantitative immunodiffusion tests. Strains which carry theH-2 ^q haplotype are high responders,H-2 ^k strains are intermediate in response, whileH-2 ^b andH-2 ^v strains produce no detectable antibody. The characteristic response patterns of high and intermediate responders were manifest by day 35 of immunization and continued as discrete response types after a second booster. Quantitative data in the immune response of the intra-H-2 recombinant B10.A(4R) suggest that the recombination event which established theH-2 ^h4 chromosome disturbs the proper function of the genetic determinant controlling response to Slp.     

Production of 1,3-Propanediol by Clostridium butyricum VPI 3266 in continuous cultures with high yield and productivity

The effects of dilution rate and substrate feed concentration on continuous glycerol fermentation by Clostridium butyricum VPI 3266, a natural 1,3-propanediol producer, were evaluated in this work. A high and constant 1,3-propanediol yield (around 0.65 mol/mol), close to the theoretical value, was obtained irrespective of substrate feed concentration or dilution rate. Improvement of 1,3-propanediol volumetric productivity was achieved by increasing the dilution rate, at a fixed feed substrate concentration of 30, 60 or 70 g l⁻¹. Higher 1,3-propanediol final concentrations and volumetric productivities were also obtained when glycerol feed concentration was increased from 30 to 60 g l⁻¹, at D=0.05–0.3 h⁻¹, and from 60–70 g l⁻¹, at D=0.05 and 0.1 h⁻¹·30 g l⁻¹ of 1,3-propanediol and the highest reported value of productivity, 10.3 g l⁻¹ h⁻¹, was achieved at D=0.30 h⁻¹ and 60 g l⁻¹ of feed glycerol. A switch to an acetate/butyrate ratio higher than one was observed for 60 g l⁻¹ of feed glycerol and a dilution rate higher than 0.10 h⁻¹; moreover, at D=0.30 h⁻¹ 3-hydroxypropionaldehyde accumulation was observed for the first time in the fermentation broth of C. butyricum.     

1,3-Propandiol production by engineered Hansenula polymorpha expressing dha genes from Klebsiella pneumoniae

Currently, 1,3-propanediol (1,3-PD) is an important chemical widely used in polymer production, but its availability is being restricted owing to its expensive chemical synthesis. A methylotrophic yeast Hansenula polymorpha was engineered by expression of dhaB1, dhaB2, dhaB3, dhaB _RA1 and dhaB _RA2 encoding glycerol dehydratase complex and dhaT encoding 1,3-PD oxidoreductase from Klebsiella pneumoniae under direction of promoter of glyceraldehyde-3 phosphate dehydrogenase (GAPDH). The engineered recombinant yeast strain can produce 1,3-PD from glucose (2.4 g L⁻¹) as well as glycerol (0.8 g L⁻¹), which might lead to a safe and cost-effective method for industrial production of 1,3-PD from various biomass resources.     

A major histocompatibility complex class I allele shared by two species of chimpanzee

 Little is known regarding the rates at which natural selection can modify or retain antigen presenting alleles at the major histocompatibility complex (MHC). Discovery of identical [1101 base pairs (bp)] coding regions at the MHC class I C locus in Pan troglodytes and Pan paniscus, chimpanzee species that diverged ∼2.3 million years ago, now indicates that a class I allotype can survive for at least this period. Remarkable conservation was also reflected in the (1799 bp) introns where a maximum of only six substitutions distinguished five alleles (three from P. troglodytes and two from P. paniscus) that encoded the identical heavy chain allotype. Analysis of a more distantly related human allele, HLA-Cw ^* 0702, corroborated that intron variation was non-uniform along the gene. Thus we provide a clear reference frame for the lifetime of an MHC class I allotype, a direct estimate of allelic substitution rates, and evidence for an unusual evolution of MHC class I introns. Received: 13 August 1997     

Consequences of cps mutation of Klebsiella pneumoniae on 1,3-propanediol fermentation

The filtration in 1,3-propanediol (1,3-PD) downstream process is influenced by the large amounts of capsular polysaccharides (CPS) produced by Klebsiella pneumoniae CGMCC 1.6366. The morphological and fermentation properties were investigated with the CPS-deficient mutant K. pneumoniae CGMCC 1.6366 CPS. Similar biomass was obtained with CGMCC 1.6366, and the mutant strain in batch cultures indicating the cell growth was slightly inhibited by CPS defection. The viscosity of fermentation broth by mutant strain decreased by 27.45%. The flux with ceramic membrane filter was enhanced from 168.12 to 303.6 l h⁻¹ m⁻², exhibiting the great importance for downstream processing of 1,3-PD fermentation. The products spectrum of mutant isolate changed remarkably regarding to the concentration of fermentation products. The synthesis of important 1,3-PD and 2,3-butanediol was enhanced from 9.73 and 4.06 g l⁻¹ to 10.37 and 4.77 g l⁻¹ in batch cultures. The noncapsuled K. pneumoniae provided higher 1,3-PD yield of 0.54 mol mol⁻¹ than that of encapsuled wild parent in batch cultures. The fed-batch fermentation of mutant strain resulted in 1,3-PD concentration, yield, and productivity of 78.13 g l⁻¹, 0.53 mol mol⁻¹, and 1.95 g l⁻¹ h⁻¹, respectively.     

Evolution of the rabbit immunoglobulin κ chain genes

We have analyzed the organization and the structure of rabbit chain genes encoding b allotypes in wild rabbits. The 1 gene of the b95 allotype was cloned and its structure determined. The J region is composed of five segments but only J2 appears to be functional and is identical to the J2 segment of the b4 allotype. The J region is highly conserved among the various b allotypes, whereas the constant region exon displays a high level of differences when compared with other allotypes (9%–30% of different amino acids). The b95 J region is closer to that of b4^var and the constant region to b5 allotype constant region. Alignment of nucleotide sequences revealed that the constant region exon displays segmental similarities with b4 and bas constant regions. The mosaic structure of b95 allotype gene indicates that complex allotypes of 1 genes may result from genetic exchanges of gene conversion between the different genes.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide database and have been assigned the accession number M22542. Address correspondence and offprint requests to: P.-A. Cazenave.     

RNA conversion of lymphoid cells to synthesize allogeneic immunoglobulins in vivo

Ribonucleic acid extracts (“5 day immune” and “nonimmune”-RNA) obtained from lymph nodes and spleens of rabbits homozygous for the b⁴ or b⁵ allele of light chain immunoglobulin allotypes were injected iv into nonimmunized rabbits homozygous for the alternate allele. The recipient rabbits were then given multiple iv injections of sheep red blood cells (SRBC). The spleens were assayed 13, 21, and 37 days following the RNA injection for “direct” IgM and “indirect” IgG plaque forming cells (PFC) specific for SRBC. The b4 or b5 light chain allotype and the a1, a2, and a3 heavy chain allotype of the antibody in the plaques was identified by radioautography and by inhibition of plaque formation using anti-allotype antibodies. The b light chain allotype of the RNA donor was identified in 22–32% of the IgM plaques and in 25–42% of the IgG plaques. The allotype of the host rabbit b light chain allotype was identified in 56–67% of the IgM plaques and in 57–71% of the IgG plaques. Likewise the a heavy chain allotype of the RNA donor was identified in 10–19% of the IgM plaques and in 12–19% of the IgG plaques. The allotype of the host rabbit a heavy chain allotype was identified in 51–60% of the IgM plaques and in 55–63% of the IgG plaques. The concentrated lysates of spleen and lymph node cells were also analyzed for immunoglobulins of each light chain allotype by immunodiffusion with radiolabeled antibody. The allotype of both the RNA donor rabbit and host rabbit were found in most of the lysates of lymphoid tissues and in some of the IgG isolated from the serum and concentrated.