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PubMed1995

An investigation of sources of variation in calcium absorption efficiency.

To examine putative sources of interindividual variation in calcium absorption efficiency, we studied 41 healthy premenopausal women (mean age, 36.4 yr). About half were randomized to pretreatment with supplemental 25-hydroxyvitamin D (25OHD; 20 micrograms/day [corrected] for approximately 34 days) before testing. We measured dietary factors, humoral regulators, intestinal motility, mucosal histology, mucosal vitamin D receptor levels, and calcium absorption efficiency. In winter tests, but not in summer tests, calcium absorption fraction was significantly higher in the pretreated group (mean, 0.465 vs. 0.387). Serum 25OHD, intestinal transit, and urinary calcium to creatinine ratio were all significantly and positively correlated to calcium absorption efficiency. However, neither the level of 1,25-dihydroxyvitamin D receptors in duodenal mucosa nor circulating 1,25-dihydroxyvitamin D was related to calcium absorption efficiency. These findings, which are consistent with other published human data, suggest that 25OHD plays a more prominent role in the regulation of calcium absorption than is generally believed. In a multiple regression model, serum 25OHD, mouth to cecum transit time, and fasting urinary calcium/creatinine ratio explained 44% of the observed variation in calcium absorption efficiency.

Absorption↗

PubMed2000

Normalisation of tissue factor pathway inhibitor activity after glycaemic control optimisation in type 1 diabetic patients.

UNLABELLED: Increased plasma concentrations of various markers of endothelial damage have been observed in type I diabetic patients, particularly in those with microangiopathy. OBJECTIVE: To evaluate the effect of near-normalisation of glycaemic control on different markers of endothelial injury involved in haemostasis in poorly-controlled type 1 diabetic patients. MATERIAL AND METHODS: TFPI, thrombomodulin (TM), plasminogen activator inhibitor, tissue-type plasminogen activator and von Willebrand factor were measured in 14 poorly-controlled type 1 diabetic patients free of diabetes-related complications (8 men, 6 women; mean age 29.8 +/- 9.9 years) before (baseline) and after 3 months of intensive therapy and in 14 sex-, age- and BMI-matched control subjects. RESULTS: After a mean follow-up of 107 +/- 49 days (56-210), HbA1c decreased from 11.2 +/- 2.3 to 6.7 +/- 0.7% (p <0.0001). TFPI activity at baseline was higher than in the control group (126.9 +/- 34 vs 92.0 +/- 13%, p <0.005) and decreased after good glycaemic control was achieved (p <0.005), becoming similar to that in the control group (91.0 +/- 16.5%). The TFPI descent correlated with the variations observed in HbA1c (p <0.05; r = 0.54). TM levels at baseline were significantly higher than in the control group (42.3 +/- 9.1 vs 29.00 +/- 10.9; p <0.005) and did not change. The remaining parameters studied were similar between patients and controls and did not change after glycaemic optimisation. CONCLUSIONS: Optimisation of glycaemic control normalises the increased activity of TFPI but not the higher TM levels observed in poorly-controlled type I diabetic patients without chronic complications.

Adolescent↗

PubMed2003

[Asymptomatic glycemic instability: how to measure it and which clinical applications? ].

The glycemic variations observed in nondiabetic subjects are primarily related to the post-prandial metabolic responses generated by the food intake. This physiological glycemic variability is reproducible between two successive days under conditions of similar meals and activities. In insulin-treated diabetic patients, glycemic instability is directly related to loss of glucose homeostasis due to the failure then the deficiency of endogenous insulin secretion, but its physiopathological implication in term of diabetic angiopathy risk remains to be determined. Other exogenous glycemic instability factors are known and have to be corrected (not adapted repartition of the meals and/or the insulin doses during the day, inappropriate choices in insulin regimens, errors in insulin adjustments, inadequate insulin injection). Classical glycemic measurements used to appreciate the quality of the glycemic control do not provide or give partial and erroneous information on quality of glycemic stability. It's particularly the case for glycated hemoglobin and glycemic average. In order to exactly quantify glycemic variability, specific tools of measurement or calculation can evaluate the intra-day glycemic variations or excursions (MAGE), the day-to-day glycemic variations or excursions (MODD), the meal-related glycemic excursions (MIME) or the risk of severe hypoglycemia (LBGI). Some of these tools are easy to use, other much complex or difficult to apply in clinical practice, even by using new methods such as the continuous glucose monitoring system (CGMS). Thus, asymptomatic glycemic variability is related to loss of glucose homeostasis, but also to irrelevant or incompatibility of the treatments used to obtain glucose control in insulin-treated diabetic patients. The evaluation of glucose instability can be provided using new methods of glucose monitoring and could be useful to optimize the therapeutic regimens in some of these diabetic patients.

Blood Glucose↗

PubMed1999

Poisson distribution of male mating success in laboratory populations of Drosophila melanogaster.

Variation among males and females in reproductive success is a major determinant of effective population size. Most studies of male mating success in Drosophila, however, have been done under conditions very different from those in typical cultures. We determined the distribution of male mating success in five laboratory populations of D. melanogaster maintained on a 14 d, discrete generation cycle fairly representative of standard Drosophila cultures. Mating success was measured as the number of matings a male could achieve under conditions closely approximating a regular culture vial of these populations. Preliminary studies determined that most mating in these populations occurred within 14 h of the flies attaining sexual maturity. Consequently, individual virgin males were marked with white paint on their thorax, put into vials with varying numbers of unmarked virgin flies of both sexes, and monitored continuously for matings over a period of up to 14 h. At various times during the assay, virgin males and females were added to these vials in proportions simulating the pattern of eclosion in culture vials. The observed variation in the number of matings per male in the five populations was, by and large, consistent with a Poisson distribution, suggesting that male mating success in short-generation-time, discrete-generation laboratory cultures of D. melanogaster may fulfil a fundamental assumption of the Wright-Fisher model of genetic drift in finite populations.

Animals↗

PubMed1989

Cytoplasmic genetic effects and growth of hybrid mice.

Variation in cellular biochemical functions controlled by cytoplasmic genes was studied in relation to phenotypic differences between progeny of reciprocal hybrid female mice. Least squares procedures were used to test for differences in mitochondrial respiratory metabolism and in capacity for ATP synthesis, and differences in growth of progeny of hybrid dams. Under identical nuclear influences, mitochondria of A/J and C57BL/6J cytoplasms differed (P less than .10 to P less than .01) from those of BALB/cJ cytoplasm in energy conservation. No differences were detected in mitochondrial efficiency between BALB/cJ cytoplasm evaluated in different nuclear environments. Three-way cross progeny of C57BL/6J x BALB/cJ reciprocal hybrid females mated to DBA/2J males differed (P less than .05) in litter weight at weaning and 1 wk and 2 wk postweaning. The F2 progeny of reciprocal C57BL/6J x BALB/cJ dams and F2 and three-way cross progeny of reciprocal A/J x BALB/cJ dams did not differ in weight at any age measured. Across all genotypes of dam, rank correlations of mitochondrial traits with F2 litter weights were nonsignificant. Observed variation in mitochondrial functions partially controlled by cytoplasmic genes did not limit mouse growth under these experimental conditions.

Adenosine Triphosphate↗

PubMed2004

Population genetic variation in gene expression is associated with phenotypic variation in Saccharomyces cerevisiae.

BACKGROUND: The relationship between genetic variation in gene expression and phenotypic variation observable in nature is not well understood. Identifying how many phenotypes are associated with differences in gene expression and how many gene-expression differences are associated with a phenotype is important to understanding the molecular basis and evolution of complex traits. RESULTS: We compared levels of gene expression among nine natural isolates of Saccharomyces cerevisiae grown either in the presence or absence of copper sulfate. Of the nine strains, two show a reduced growth rate and two others are rust colored in the presence of copper sulfate. We identified 633 genes that show significant differences in expression among strains. Of these genes, 20 were correlated with resistance to copper sulfate and 24 were correlated with rust coloration. The function of these genes in combination with their expression pattern suggests the presence of both correlative and causative expression differences. But the majority of differentially expressed genes were not correlated with either phenotype and showed the same expression pattern both in the presence and absence of copper sulfate. To determine whether these expression differences may contribute to phenotypic variation under other environmental conditions, we examined one phenotype, freeze tolerance, predicted by the differential expression of the aquaporin gene AQY2. We found freeze tolerance is associated with the expression of AQY2. CONCLUSIONS: Gene expression differences provide substantial insight into the molecular basis of naturally occurring traits and can be used to predict environment dependent phenotypic variation.

Color↗

PubMed1994

Rod outer segment structure influences the apparent kinetic parameters of cyclic GMP phosphodiesterase.

Cyclic GMP hydrolysis by the phosphodiesterase (PDE) of retinal rod outer segments (ROS) is a key amplification step in phototransduction. Definitive estimates of the turnover number, kcat, and of the Km are crucial to quantifying the amplification contributed by the PDE. Published estimates for these kinetic parameters vary widely; moreover, light-dependent changes in the Km of PDE have been reported. The experiments and analyses reported here account for most observed variations in apparent Km, and they lead to definitive estimates of the intrinsic kinetic parameters in amphibian rods. We first obtained a new and highly accurate estimate of the ratio of holo-PDE to rhodopsin in the amphibian ROS, 1:270. We then estimated the apparent kinetic parameters of light-activated PDE of suspensions of disrupted frog ROS whose structural integrity was systematically varied. In the most severely disrupted ROS preparation, we found Km = 95 microM and kcat = 4,400 cGMP.s-1. In suspensions of disc-stack fragments of greater integrity, the apparent Km increased to approximately 600 microM, though kcat remained unchanged. In contrast, the Km for cAMP was not shifted in the disc stack preparations. A theoretical analysis shows that the elevated apparent Km of suspensions of disc stacks can be explained as a consequence of diffusion with hydrolysis in the disc stack, which causes active PDEs nearer the center of the stack to be exposed to a lower concentration of cyclic GMP than PDEs at the disc stack rim. The analysis predicts our observation that the apparent Km for cGMP is elevated with no accompanying decrease in kcat. The analysis also predicts the lack of a Km shift for cAMP and the previously reported light dependence of the apparent Km for cGMP. We conclude that the intrinsic kinetic parameters of the PDE do not vary with light or structural integrity, and are those of the most severely disrupted disc stacks.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2005

Profiling cytogenetic diversity with entropy-based karyotypic analysis.

Regardless the high degree of variation observed in solid tumor karyotypes, the use of diversity as a measurable phenomenon remains unexplored. Here we present a systematic cytogenetic analysis using Shannon's entropy as a measure for karyotypic diversity. Karyotypes from 14 epithelial tumor types (n = 1232) have the aneuploidy status scored, resulting in highly asymmetrical sample distribution, for which we determine the index of diversity (Shannon H') of structural and numerical chromosomal aberrations. Since karyotypic diversity is tissue-specific, this approach may give rise to new insights into the processes that may account for aneuploidy progression and solid tumor outcomes.

Chromosome Aberrations↗

PubMed2006

Genealogy of the nuclear beta-fibrinogen locus in a highly structured lizard species: comparison with mtDNA and evidence for intragenic recombination in the hybrid zone.

The study of nuclear genealogies in natural populations of nonmodel organisms is expected to provide novel insights into the evolutionary history of populations, especially when developed in the framework of well-established mtDNA phylogeographical scenarios. In the Iberian Peninsula, the endemic Schreiber's green lizard Lacerta schreiberi exhibits two highly divergent and allopatric mtDNA lineages that started to split during the late Pliocene. In this work, we performed a fine-scale analysis of the putative mtDNA contact zone together with a global analysis of the patterns of variation observed at the nuclear beta-fibrinogen intron 7 (beta-fibint7). Using a combination of DNA sequencing with single-strand conformational polymorphism (SSCP) analysis, we show that the observed genealogy at the beta-fibint7 locus reveals extensive admixture between two formerly isolated lizard populations while the two mtDNA lineages remain essentially allopatric. In addition, a private beta-fibint7 haplotype detected in the single population where both mtDNA lineages were found in sympatry is probably the result of intragenic recombination between the two more common and divergent beta-fibint7 haplotypes. Our results suggest that the progressive incorporation of nuclear genealogies in investigating the ancient demography and admixture dynamics of divergent genomes will be necessary to obtain a more comprehensive picture of the evolutionary history of organisms.

Animals↗

PubMed1991

Assessing the role of APNH, a gene encoding for a human amiloride-sensitive Na+/H+ antiporter, on the interindividual variation in red cell Na+/Li+ countertransport.

The "reverse genetic" approach to essential hypertension is complicated by the fact that blood pressure is a heterogeneous, quantitative, complex trait. One strategy is to use "intermediate phenotypes" that are not only associated with hypertension but that also have a simple mode of inheritance, compatible with the action of a single gene. Red cell sodium-lithium countertransport (SLC) is one of the best characterized intermediate phenotypes for hypertension. The similarity in stoichiometry and kinetics between SLC and Na+/H+ exchange has led to the proposal that the gene encoding the Na+/H+ antiporter (APNH) may be responsible for the individual variance in SLC. We have tested this hypothesis by both an association study and Haseman and Elston's sib pair method of linkage analysis, by using a polymorphism at the APNH locus detected by denaturing gradient gel electrophoresis. Both analytical techniques were performed before and after correction of SLC values for known covariates. There was no significant association between mean SLC values and any of the three possible genotypes of the APNH locus either before or after regressing out covariates (F = 0.64 and P greater than 0.52; F = 0.63 and P greater than 0.53, respectively). Linkage analysis similarly failed to demonstrate a relationship between the squared difference in SLC values and the identity by descent status for APNH as well as other loci that map close to APNH (D1S57, RH, and ALPL). Taking these results together, we conclude that mutations at the APNH locus are not responsible for the observed variation in SLC values.

Amiloride↗

PubMed1999

Broiler breast meat color variation, pH, and texture.

Four experiments were conducted to determine the range of breast meat color variation observed in commercial processing plants and its relationship to muscle pH and texture. Boneless, skinless breast fillets were collected weekly from the deboning lines of five commercial processing plants over a 4-wk period. Plant personnel selected breast fillets based on their appearance as being "lighter than normal," "normal," or "darker than normal" in color. Five representative fillets of each appearance classification were transported to a central laboratory for analyses of visual score (1 to 5 with 1 = light, 3 = normal, or 5 = dark), instrumental color, muscle pH, and Allo-Kramer shear (n = 300). Visual scores, lightness (L*), redness (a*), and pH were different (P<0.05) among the three appearance groups, with no significant differences in yellowness (b*). Visual scores averaged 2.4, 3.0, and 3.6, L* was 48.8, 45.6, and 43.1, and pH was 5.63, 5.70, and 5.81 for the lighter, normal, and darker fillets, respectively. There were no significant effects of color group on breast meat texture. Correlations between the color values and pH, however, were all highly significant. These results not only indicate that there are wide variations in breast meat color in commercial production, but they also demonstrate a strong relationship between breast meat color and muscle pH.

Animals↗

PubMed2006

Features associated with germline CDKN2A mutations: a GenoMEL study of melanoma-prone families from three continents.

BACKGROUND: The major factors individually reported to be associated with an increased frequency of CDKN2A mutations are increased number of patients with melanoma in a family, early age at melanoma diagnosis, and family members with multiple primary melanomas (MPM) or pancreatic cancer. METHODS: These four features were examined in 385 families with > or =3 patients with melanoma pooled by 17 GenoMEL groups, and these attributes were compared across continents. RESULTS: Overall, 39% of families had CDKN2A mutations ranging from 20% (32/162) in Australia to 45% (29/65) in North America to 57% (89/157) in Europe. All four features in each group, except pancreatic cancer in Australia (p = 0.38), individually showed significant associations with CDKN2A mutations, but the effects varied widely across continents. Multivariate examination also showed different predictors of mutation risk across continents. In Australian families, > or =2 patients with MPM, median age at melanoma diagnosis < or =40 years and > or =6 patients with melanoma in a family jointly predicted the mutation risk. In European families, all four factors concurrently predicted the risk, but with less stringent criteria than in Australia. In North American families, only > or =1 patient with MPM and age at diagnosis < or =40 years simultaneously predicted the mutation risk. CONCLUSIONS: The variation in CDKN2A mutations for the four features across continents is consistent with the lower melanoma incidence rates in Europe and higher rates of sporadic melanoma in Australia. The lack of a pancreatic cancer-CDKN2A mutation relationship in Australia probably reflects the divergent spectrum of mutations in families from Australia versus those from North America and Europe. GenoMEL is exploring candidate host, genetic and/or environmental risk factors to better understand the variation observed.

Australia↗

PubMed2006

Gender differences in stroke care decision-making.

BACKGROUND: Women are less likely than men to receive some stroke care interventions. It is not known whether gender differences in patient preferences explain some of the observed variations in stroke care delivery. METHODS: Outpatients with and without a history of cerebrovascular disease were recruited from stroke, vascular, and general internal medicine ambulatory clinics between September 2002 and October 2003. Self-administered surveys described hypothetical scenarios, and participants were asked if they would accept therapy with thrombolysis for acute ischemic stroke or carotid endarterectomy for secondary stroke prevention. The surveys also included questions on sociodemographic factors and decision-making preferences. RESULTS: A total of 586 patients (45% women) completed the survey. Women were less likely than men to accept thrombolysis (79% vs. 86%, P=0.014), even after adjustment for other factors (adjusted odds ratio [OR] 0.58, 95% confidence interval [CI] 0.37-0.92). Women and men were equally likely to accept carotid endarterectomy (82% vs. 84%, P=0.502), even after adjustment for other factors (adjusted OR 0.94, 95% CI 0.58- 1.53). Women were less confident in their decisions, were more risk averse, and would have preferred more information to assist them in their decision-making. CONCLUSIONS: No gender differences were found in patient preferences for carotid surgery. However, we observed gender differences in patient preferences for thrombolysis and in general attitudes toward stroke care decision-making. Health care providers should be aware that, compared with men, women may be more concerned about risks and may require more information before they make a decision.

Data Collection↗

PubMed1996

Novel variation in the N protein of avian infectious bronchitis virus.

The nucleocapsid protein of coronaviruses has been considered highly conserved, showing greater than 94% conservation within strains of a given species. We determined the nucleotide sequence of the N gene and the 3' untranslated region (UTR) of eight naturally occurring strains of IBV which differed in pathogenicity and tissue tropism. In pairwise comparisons, the deduced amino acid sequences of N of five strains Vic S, N1/62, N9/74, N2/75, and V5/90 (group I) shared 92.3-98.8% identity. The three strains N1/88, Q3/88, and V18/91 (group II) shared 85.8-89.2% identity with each other, but only 60.0-63.3% identity with viruses of group I. Amino acid substitutions, deletions, and insertions occurred throughout the N protein and involved regions previously identified as being conserved. Despite the considerable variation observed between the two virus groups, all N proteins contained a high proportion of basic residues, 80% of which were conserved in position. In addition, all strains contained approximately 30 serine residues of which 10 were conserved, the majority occurring between positions 168 and 194. As for all other coronaviruses, the region between positions 92 and 103 was highly conserved. Hence, a large number of amino acid changes can be tolerated within the N protein without affecting its integrity or functioning. The 3' UTR immediately downstream from the N gene was highly heterogeneous with extensive deletions occurring in the group II strains.

Amino Acid Sequence↗

PubMed2003

Utilisation of antibiotics in young children: opposite relationships to adult educational levels in Danish and Swedish counties.

BACKGROUND: Antibiotic utilisation varies profoundly among and within countries, and the extent of antibiotic utilisation correlates with the frequency of bacterial resistance, particularly among children. Hence, it is important to assess which factors may influence prescribing. In addition to variations in morbidity, health-care organisation, drug regulatory and supply systems, prescriber's attitudes, parents' behaviour, attitudes and socio-economic positions seem important. We compared socio-economic position (educational level of adults) and antibiotic utilisation in children in the municipalities within a Danish and a Swedish county which are geographically close, have similar social and economic development, and similar drug regulatory and supply systems. METHODS: Data on antibiotic utilisation (1998), expressed in defined daily doses per 1000 inhabitants per day (DDD/TID), were obtained from the Copenhagen County Health Insurance register and from the National Corporation of Swedish Pharmacies. Data on municipal educational levels were obtained from Statistics Denmark and Statistics Sweden. RESULTS: The utilisation of antibiotics in 0- to 6-year-old children was higher in the Swedish than in the Danish county but varied between the municipalities within both the Swedish (9.6-17.7 DDD/TID) and the Danish (8.0-12.9 DDD/TID) counties. Most notably, utilisation rates correlated negatively with the education levels in the Danish (r=-0.539, P=0.021) but positively in the Swedish (r=+0.390, P=0.025) municipalities. CONCLUSION: The observed variations in antibiotic prescribing may reflect different parental and/or prescriber attitudes towards use of antibiotics and they emphasise that antibiotic prescribing is influenced by factors other than the prevalence of bacterial infections. Relationships between socio-economic position (educational level) and drug utilisation should not be generalised from one area to another.

Anti-Bacterial Agents↗

PubMed2005

Mechanisms of classical crystal growth theory explain quartz and silicate dissolution behavior.

The central control of mineral weathering rates on biogeochemical systems has motivated studies of dissolution for more than 50 years. A complete physical picture that explains widely observed variations in dissolution behavior is lacking, and some data show apparent serious inconsistencies that cannot be explained by the largely empirical kinetic "laws." Here, we show that mineral dissolution can, in fact, be understood through the same mechanistic theory of nucleation developed for mineral growth. In principle, this theory should describe dissolution but has never been tested. By generalizing nucleation rate equations to include dissolution, we arrive at a model that predicts how quartz dissolution processes change with undersaturation from step retreat, to defect-driven and homogeneous etch pit formation. This finding reveals that the "salt effect," recognized almost 100 years ago, arises from a crossover in dominant nucleation mechanism to greatly increase step density. The theory also explains the dissolution kinetics of major weathering aluminosilicates, kaolinite and K-feldspar. In doing so, it provides a sensible origin of discrepancies reported for the dependence of kaolinite dissolution and growth rates on saturation state by invoking a temperature-activated transition in the nucleation process. Although dissolution by nucleation processes was previously unknown for oxides or silicates, our mechanism-based findings are consistent with recent observations of dissolution (i.e., demineralization) in biological minerals. Nucleation theory may be the missing link to unifying mineral growth and dissolution into a mechanistic and quantitative framework across the continuum of driving force.

Journal Article↗

PubMed2006

Functional polymorphisms in the mannan-binding lectin 2 gene: effect on MBL levels and otitis media.

BACKGROUND: Mannan-binding lectin (MBL) can bind to microorganisms, initiating the lectin pathway of complement activation. Aberrant MBL serum levels, caused by MBL2 gene polymorphisms, are a possible risk factor for recurrent infections. Within the 7 common MBL haplotypes, still considerable variation in MBL serum levels exists. OBJECTIVE: To investigate functional MBL levels and MBL2 polymorphisms in a large cohort of children with recurrent acute otitis media. METHODS: Twelve genetic variants in the MBL2 gene and functional MBL serum levels were determined in a cohort of children with recurrent acute otitis media. Haplotypes were constructed and associated with functional MBL serum levels and the number of otitis episodes in the previous year. RESULTS: The 7 common MBL2 haplotypes mainly determine the level of functional MBL in serum. In addition, the 3130G>C single nucleotide polymorphism, located in exon 4, further significantly influenced functional MBL levels within the LXPA haplotype. LXPA carriers with 3130G showed a significantly lower geometric mean functional MBL serum level of 0.19 mug/mL compared with 0.70 mug/mL in 3130C carriers (P = .026). Nonwild-type MBL2 carriers between 12 and 24 months had a significantly increased number of otitis episodes (5.1/y) compared with wild-type MBL2 carriers (4.1/y; P = .027). In older children, this association was not found anymore. CONCLUSION: Additional single nucleotide polymorphisms within the 7 common haplotypes can further explain the observed variation in functional MBL serum levels. MBL seems to be of particular clinical importance during early childhood, when maternally derived antibodies have waned, and protective adaptive immunity is not well developed yet. CLINICAL IMPLICATIONS: Single nucleotide polymorphisms in the promoter region, in exon 1, and in exon 4 of MBL2 contribute to increased risk for otitis media in children younger than 2 years.

Acute Disease↗

PubMed1998

Mytilus protamine-like sperm-specific protein genes are multicopy, dispersed, and closely associated with hypervariable RFLP regions.

Protamine-like sperm packaging proteins replace somatic histones during spermatogenesis, and although the proteins have been well-characterized in many marine invertebrate species, little is known of the arrangement of the genes. The research described here was designed to determine the sequence and structure of the protamine-like PL-III (or "phi 1") gene in marine mussels (Mytilus spp). The PL-III sequence was found to be extremely variable not only among the closely related Mytilus species, but also within species and populations. The variation observed among eight PL-III sequences from a single individual indicated that PL-III was probably multiple-copied. Southern analysis confirmed that PL-III, and another protamine-like gene, (PL-II), were multicopy and dispersed, as well as associated with a hypervariable element. Some PL-III genes are also arranged in nontandem clusters, and the spacer regions are probably the source of the hypervariable nature of the Southern blots. The arrangement of the protamine-like genes in Mytilus appears to be closer to that reported for histones than protamines; however, their association with a hypervariable element is novel.

Amino Acid Sequence↗