Experimental manipulation reveals a trade-off between weapons and testes.

Theory predicts a trade-off between sexually selected weapons used to secure mates and post-copulatory traits used to maximize fertilization success. However, individuals that have a greater capacity to acquire resources from the environment may invest more in both pre- and post-copulatory traits, and trade-offs may not be readily apparent. Here, we manipulate the phenotype of developing individuals to examine allocation trade-offs between weapons and testes in Mictis profana (Hemiptera: Coreidae), a species where the hind legs are sexually selected weapons used in contests over access to females. We experimentally prevented males from developing weapons by inducing them to autotomize their hind legs before the final moult to adulthood. We compared trait expression in this group to males where autotomy was induced in the mid-legs, which are presumably not under sexual selection to the same extent. We found males without weapons invested proportionally more in testes mass than those with their mid-legs removed. Males that developed to adulthood without weapons did not differ from the mid-leg removal group in other traits potentially under precopulatory sexual selection, other post-copulatory traits or naturally selected traits. In addition, a sample of adult males from the same population in the wild revealed a positive correlation between investment in testes and weapons. Our study presents a critical contribution to a growing body of literature suggesting the allocation of resources to pre- and post-copulatory sexual traits is influenced by a resource allocation trade-off and that this trade-off may only be revealed with experimental manipulation.

The tale of the shrinking weapon: seasonal changes in nutrition affect weapon size and sexual dimorphism, but not contemporary evolution.

Sexually selected traits are often highly variable in size within populations due to their close link with the physical condition of individuals. Nutrition has a large impact on physical condition, and thus, any seasonal changes in nutritional quality are predicted to alter the average size of sexually selected traits as well as the degree of sexual dimorphism in populations. However, although traits affected by mate choice are well studied, we have a surprising lack of knowledge of how natural variation in nutrition affects the expression of sexually selected weapons and sexual dimorphism. Further, few studies explicitly test for differences in the heritability and mean-scaled evolvability of sexually selected traits across conditions. We studied Narnia femorata (Hemiptera: Coreidae), an insect where males use their hind legs as weapons and the femurs are enlarged, to understand the extent to which weapon expression, sexual dimorphism and evolvability change across the actual range of nutrition available in the wild. We found that insects raised on a poor diet (cactus without fruit) are nearly monomorphic, whereas those raised on a high-quality diet (cactus with ripe fruit) are distinctly sexually dimorphic via the expression of large hind leg weapons in males. Contrary to our expectations, we found little evidence of a potential for evolutionary change for any trait measured. Thus, although we show weapons are highly condition dependent, and changes in weapon expression and dimorphism could alter evolutionary dynamics, our populations are unlikely to experience further evolutionary changes under current conditions.

Multi-frame super-resolution algorithm for complex motion patterns.

Multi-frame super-resolution algorithms offer resolution enhancement for sequences of images with sampling limited resolution. However, classical approaches have been constrained by the accuracy of motion estimation while nonlocal approaches that use implicit motion estimation have attained only modest resolution improvement. In this paper, we propose a new multi-frame optical flow based super-resolution algorithm, which provides significant resolution enhancement for image sequences containing complex motion. The algorithm uses the standard camera image formation model and a variational super-resolution formulation with an anisotropic smoothness term adapting to local image structures. The key elements enabling super-resolution of complex motion patterns are the computation of two-way optical flow between the images and use of two corresponding uncertainty measures that approximate the optical flow interpolation error. Using the developed algorithm, we are able to demonstrate super-resolution of images for which optical flow estimation experiences near breakdown, due to the complexity of the motion patterns and the large magnitudes of the displacements. In comparison, we show that for these images some conventional super-resolution approaches fail, while others including nonlocal super-resolution technique produce distortions and provide lower (1-1.8 dB) image quality enhancement compared to the proposed algorithm.

The form of sexual selection arising from male-male competition depends on the presence of females in the social environment.

Sexual selection arises from social interactions, and if social environments vary so too should sexual selection. For example, male-male competition often occurs either in the presence or in the absence of females, and such changes in the social environment could affect the form and strength of sexual selection. Here we examine how the presence of a female influences selection arising from male-male competition in a leaf-footed cactus bug, Narnia femorata, which has a resource defence mating system. Males compete for territories on cacti because females lay eggs on the cactus plants. Females are not always present when this competition first occurs; however, the presence or absence of the female matters. We found that both the form and strength of selection on male traits, those traits that influenced success in intrasexual competition, depended on the social context. When a female was not present, male size and the area of the sexually dimorphic hind legs was only marginally important to winning a contest. However, males with larger overall size and leg area were more likely to win in the presence of a female. There was also positive quadratic selection on these traits when a female was present with both the largest and the smallest males winning. The implication is unexpected alternative strategies when females are present. Our results support the notion that sexual selection should be studied under all relevant social contexts.

Developmental Nutrition Affects the Structural Integrity of a Sexually Selected Weapon.

Males in many species engage in physical combat over access to mates, and sexual selection has led to the evolution of weapons to enhance contest performance. The size of these often-elaborate structures is known to be exquisitely sensitive to nutrition. However, we know very little about the degree to which nutrition affects other attributes of animal weapons that can be crucial to fighting. In this study, we investigated the impact of natural dietary variation on weapon structural integrity in a fighting insect, Narnia femorata (Hemiptera: Coreidae). Males in this species display their enlarged, spiny hind legs to other males, and these legs serve as weapons in aggressive physical contests where they are used to strike and squeeze opponents. N. femorata feeds on the fruit of prickly pear cactus and sets up territories on this plant. In North Central Florida the prickly pear Opuntia mesacantha ssp. lata blooms and begins to produce fruits in April and May. N. femorata has multiple, overlapping generations while the green fruits slowly ripen over the next several months. We examined insects reaching adulthood at two nearby time points in this range, June and July, to test the influence of the nutrition provided by ripening green cactus fruit on weapon size and its ability to resist puncture. We also raised insects on cactus with red, ripe fruit for comparison. We found a striking effect of cactus fruit phenology on weapons. Insects raised with the more mature green fruit (those in the second cohort) had 71% larger weapon area and 4.4 times greater puncture resistance than those raised on the early green fruit (those in the first cohort). In contrast, insects raised on red, ripe fruit were moderate in size, had high puncture resistance, and they changed little phenotypically from the first to second cohort. Increased structural integrity of the hind femur weapon was associated with the increased body size that came with better nutrition. This pattern highlights that cuticle thickness increased or its material properties changed when weapons were larger. Importantly, effects of nutrition on puncture resistance also transcended size. Insects of the same size had greater structural integrity if they received superior nutrition. Sexually selected weapons are often used as visual signals to conspecifics before fights, and this work hints that the size of the weapons may be a poor signal of weapon performance when nutrition is variable.

p53 in chronic myelogenous leukemia. Study of mechanisms of differential expression.

The p53 is a nuclear protein that is associated with normal cellular proliferation and can cooperate with Ha-ras in causing cellular transformation in vitro. Lineage association is known to exist between p53 expression and normal lymphopoiesis, but not myelopoiesis. We studied the expression of p53 using chronic myelogenous leukemia (CML) cell lines, somatic hybrids of these cells, and leukemic cells from CML patients. Lymphoid CML lines expressed both p53 mRNA and protein. We also analyzed p53 synthesis by two B-lymphoid lines from the same CML patient; cells of one line were derived from the neoplastic clone, cells of the other were derived from the normal clone. Both synthesized equal amounts of a phosphorylated p53 protein. None of the myeloid CML lines expressed detectable p53 protein and two of four expressed negligible p53 mRNA. Two other myeloid CML lines and myeloid cells from three of four patients expressed p53 mRNA. These findings suggest that expression of the gene is not regulated normally in CML. Several approaches were pursued to explore the differential expression of p53. Southern blot analyses showed no gross alterations in the p53 gene from cells of either the expressing or the nonexpressing lines. No difference in the pattern of demethylated CpG sites was noted in the region of the p53 gene in cells from K562 (myeloid p53 nonexpressor) and in BV173 (lymphoid p53 expressor). The sites of demethylation clustered in and around the p53 promoter in both cell lines. Somatic hybrids formed between a p53 mRNA nonexpressor myeloid line (K562) and the parental p53 expressor lymphoid lines (Daudi, PUT) produced p53 mRNA and protein, suggesting that p53 is a dominantly expressed protein and that lack of expression in myeloid cells is not mediated by a trans-acting negative regulatory protein. DNA transfection experiments performed using the indicator gene chloramphenicol acetyltransferase attached to promoter sequences of p53 showed that these constructs were equally activated in BV173 (p53 expressor) and K562 (p53 mRNA nonexpressor). The mechanism of p53 regulation in CML remains unclear.

DLK1: increased expression in gliomas and associated with oncogenic activities.

DLK1 (delta-like) is a transmembrane and secreted protein in the epidermal growth factor-like homeotic family. Although expressed widely during embryonic development, only a few tissues retain the expression in adults. Neuroendocrine tumors often highly express this protein; therefore, we hypothesized that brain tumors might also express it. This study found that the expression of DLK1 in gliomas was higher than that in normal brain (P < 0.05). After stable transfection of a DLK1 cDNA expression vector into GBM cell lines, their proliferation was increased. Furthermore, they lost contact inhibition, had enhanced anchorage-independent growth in soft agar, and had significantly greater capacity to migrate. Western blot studies showed that expression of cyclin D1, CDK2, and E2F4 were increased, and Rb levels were decreased in these cells. DLK1 was found on the cell surface and secreted in the medium from the transfected GBM cells. DLK1-enriched condition medium stimulated the growth of glioblastoma multiforme cell lines and explants. DLK1 antibody blocked cell growth stimulated by DLK1. In summary, these results suggest that DLK1 may play a role in the formation or progression of gliomas.

1,25-Dihydroxyvitamin D3 modulates the expression of a lymphokine (granulocyte-macrophage colony-stimulating factor) posttranscriptionally.

We recently showed that 1,25(OH)2D3 sensitively inhibited the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in normal human mitogen-activated peripheral blood lymphocytes and in the human T lymphotropic virus I immortalized T cell line known as S-LB1 at the levels of both mRNA and protein. Using S-LB1 cells as a model system the present paper identifies at least in part the mechanisms by which 1,25(OH)2D3 regulates the expression of GM-CSF. Time-course studies demonstrated that by 6 and 48 h of exposure of S-LB1 cells to 1,25(OH)2D3 (10(-8) M) the GM-CSF mRNA levels were reduced by 50 and 90%, respectively. Studies using cycloheximide as a protein synthesis inhibitor showed that the inhibitory action of 1,25(OH)2D3 on GM-CSF expression was dependent on new protein synthesis. In vitro nuclear run-on assays demonstrated that 1,25(OH)2D3 (10(-8) M) did not change the rate of transcription of the GM-CSF gene. The t1/2 of GM-CSF mRNA, however, was profoundly reduced by 1,25(OH)2D3 when transcription was blocked by actinomycin D compared with the half-life of GM-CSF in the presence of actinomycin D alone (t1/2, less than 0.5 and 4 h, respectively). Taken together, these results demonstrate that 1,25(OH)2D3 regulates expression of the lymphokine GM-CSF posttranscriptionally by influencing the stability of GM-CSF mRNA.

The p53 activation domain binds the TATA box-binding polypeptide in Holo-TFIID, and a neighboring p53 domain inhibits transcription.

Antioncogene product p53 is a transcriptional transactivator. To investigate how p53 stimulates transcription, we examined the interaction of p53 with general transcription factors in vitro. We found that p53 binds directly to the human TATA box-binding polypeptide (TBP). We also observed a direct interaction between p53 and purified holo-TFIID, a complex composed of TBP and a group of TBP-associated polypeptides known as TAFs. The p53 binding domain on TBP was mapped to the conserved region of TBP, including residues 220 to 271. The TBP binding domain on p53 was mapped to the p53 activation domain between residues 20 and 57. To analyze the significance of the p53-TBP interaction in p53 transactivation, we compared the ability of Gal4-p53 fusion proteins to bind to TBP in vitro and to activate transcription in transient transfection assays. Fusion proteins which bound to TBP activated transcription, and those that did not bind to TBP did not activate transcription to a detectable level, suggesting that a direct interaction between TBP and p53 is required for p53 transactivation. We also found that inclusion of residues 93 to 160 of p53 in a Gal4-p53 fusion repressed transcriptional activation 100-fold. Consequently, this region of p53 inhibits transcriptional activation by the minimal p53 activation domain. Highest levels of activation were observed with sequences 1 to 92 of p53 fused to Gal4, even though this construct bound to TBP in vitro with an affinity similar to that of other Gal4-p53 fusion proteins. We conclude that TBP binding is necessary for p53 transcriptional activation and that p53 sequences outside the TBP binding domain modulate the level of activation.

Dlk1 in normal and abnormal hematopoiesis.

Dlk1 (Pref-1) is a transmembrane and secreted protein, which is a member of the epidermal growth factor-like family, homologous to Notch/Delta/Serrate. We have found by real-time RT-PCR that Dlk1 mRNA levels were high in CD34(+) cells in 10 of 12 MDS samples compared with CD34(+) cells from 11 normals. Also, Dlk1 mRNA was elevated in mononuclear, low density bone marrow cells from 11/38 MDS patients, 5/11 AML M6 and 2/4 AML M7 samples. Furthermore, 5/6 erythroleukemia and 2/2 megakaryocytic leukemia cell lines highly expressed Dlk1 mRNA. Levels of Dlk1 mRNA markedly increased during megakaryocytic differentiation of both CMK megakaryoblasts as well as normal CD34(+) hematopoietic stem cells. High serum levels of Dlk1 occurred in RA (4/10) and essential thrombocythemia (2/10) patients. Functional studies showed that forced expression of Dlk1 enhanced proliferation of K562 cells growing in 1% fetal bovine serum. Analysis of hematopoiesis of Dlk1 knockout mice suggested that Dlk1 contributed to granulocyte, megakaryocyte and B-cell clonogenic growth and was needed for generation of splenic B-cells. In summary, Dlk1 is overexpressed in selected samples of MDS (especially RA and RAEB) and AML (particularly M6, M7), and it appears to be associated with normal development of megakaryocytes and B cells.

p27/Kip1 mutation found in breast cancer.

The p27/Kip1 protein belongs to the recently identified family of proteins called cyclin-dependent kinase inhibitors. These proteins play an important role as negative regulators of cell cycle-dependent kinase activity during progression of the cell cycle. Since cyclin-dependent kinase inhibitors can inhibit cell proliferation, they may have a role as tumor suppressor genes. To determine whether p27 alterations may be involved in tumorigenesis, we examined its mutational status in 36 primary breast carcinomas and 9 breast cancer cell lines using PCR-single-strand conformational polymorphism, direct DNA sequencing, and Southern blot analysis. Southern blot analysis showed no homozygous deletions of the p27 gene in either the clinical samples or cell lines. Two point mutations were found in primary tumors. One represents a previously undescribed polymorphism at codon 142; another is a nonsense mutation at codon 104. The latter mutation was absent in the normal matched control sample, and, in addition, it was accompanied with the loss of heterozygosity (LOH) of a microsatellite marker in the vicinity of the p27 gene on chromosome 12p13. These data indicate that p27 mutations are a rare event in breast cancer, but may play an important role in the development of a minority of these cancers. Furthermore, LOH analysis of the 12p13 locus revealed that an additional four of six matched DNA samples had LOH at 12p13 but did not have an alteration of the p27 gene, suggesting that another tumor suppressor gene is located on the short arm of human chromosome 12 which may be frequently involved in the pathogenesis of breast cancers.

Frequency and structure of p53 rearrangements in human osteosarcoma.

Osteosarcoma is the most frequent childhood bone cancer (Tebbi, C. K., and Gaeta, J. Pediatr. Ann., 17:285-300, 1988). Using Southern blot mapping, we found that 11 of 60 (18%) osteosarcomas had altered restriction patterns of the p53 gene and that six of these had loss of the other p53 allele. In contrast, no alteration of the p53 gene was detected in 50 samples from other types of sarcomas. Fifty % of osteosarcoma cell lines (4 of 8) also had gross rearrangements of one p53 allele with loss of the second allele, and these had no detectable p53 mRNA. Osteosarcoma cell lines with no detectable alteration of the p53 gene contained abundant p53 transcripts. Taken together, data show that human osteosarcomas can have rearrangements of the p53 gene; these rearrangements may cause loss of normal constraints on cellular growth.

p53 mutations in human lung tumors.

Mutation of one p53 allele and loss of the normal p53 allele [loss of heterozygosity (LOH)] occur in many tumors including lung cancers. These alterations apparently contribute to development of cancer by interfering with the tumor suppressor activity of p53. We directly sequenced amplified DNA in the mutational hot spots (exons 4-8) of p53 in DNA samples from 40 lung cancers. Most (31 of 40) samples were preselected for LOH in the region of p53. We detected 23 p53 mutations within these exons in 22 lung cancers; no p53 mutations were found in normal tissue of the patients. One-half of the mutations were G to T transversions on the nontranscribed strand, consistent with mutagenesis by tobacco smoke. Mutations of C to A on the nontranscribed strand, which would result from G to T mutations on the transcribed strand, were detected only in one sample. Three of 23 mutations were nonsense mutations; to date, nonsense mutations of p53 have not been reported in lung cancer. Mutation of this p53-coding region was detected in 20 of 27 small cell lung cancer samples, representing a 70% occurrence. Mutation of the p53 gene is apparently very frequent in small cell lung cancers. When LOH in the p53 region could be determined, complete concordance occurred between a sample having both a p53 mutation and LOH in the region of p53 (18 of 18 samples). Twelve samples of lung cancer had LOH in the region of p53, but the samples had no detectable p53 mutations, suggesting either alterations outside the known mutational hot spots of p53 or alterations of another unidentified tumor suppressor gene in the region of p53.

Mutational analysis of the peroxisome proliferator-activated receptor gamma gene in human malignancies.

Peroxisome proliferator-activated receptor gamma (PPARgamma) plays an important role in adipocyte differentiation and is expressed in many human malignancies, including those from prostate, breast, as well as colon. It regulates differentiation and/or cell growth of these cells. However, expression of this nuclear hormone receptor in other types of cancer, especially in hematological malignancies, remains to be fully elucidated. The PPARgamma gene has been mapped to chromosome band 3p25, where chromosomal abnormalities are observed in a variety of human malignancies. Furthermore, a recent study revealed that the PPARgamma gene is functionally mutated in sporadic colon cancer cells. Therefore, PPARgamma could be an important tumor suppressor gene. This prompted us to investigate the expression and mutational status of the PPARgamma gene in cancers of a variety of tissues. A total of 159 samples were interrogated for their expression of PPARgamma as measured by reverse transcription-polymerase chain reaction and/or Western blot analysis. In each of the samples, expression of PPARgamma was detectable. In addition, a total of 397 clinical samples and cell lines including colon, prostate, breast and lung cancers, and leukemias were analyzed for mutations of the PPARgamma gene by either reverse transcription-polymerase chain reaction-single-strand conformation polymorphism or polymerase chain reaction-single-strand conformation polymorphism analysis. No abnormalities were detectable in any of the human malignancies. On the other hand, shifted bands were easily detectable when using positive controls, which harbored the same sequence alterations reported previously in colon cancer cells. Taken together, PPARgamma is expressed in a variety of cancers, and mutation of the PPARgamma gene is a very rare event in human malignancies.

Tumor necrosis factor alpha polymorphism associated with increased susceptibility to development of adult T-cell leukemia/lymphoma in human T-lymphotropic virus type 1 carriers.

Human T-lymphotropic virus type 1 (HTLV-1) is etiologically associated with adult T-cell leukemia/lymphoma (ATL). Nevertheless, most individuals infected with HTLV-1 do not develop ATL. To attempt to identify genetic factors promoting the progression to ATL, we investigated in HTLV-1 carriers the relationship between susceptibility to ATL and several polymorphisms: the three "decreased-detoxifying" polymorphisms in GSTM1, GSTT1, and CYP1A1, the "proapoptotic" polymorphism in BCL2, and the five "high-production" polymorphisms in tumor necrosis factor alpha (TNF-alpha) using PCR-based genotyping assays. ATL patients (n = 71) were younger than HTLV-1 carriers (n = 80; 57 +/- 12 versus 63 +/- 10 years; P = 0.0017). MALE:female ratio in ATL patients was higher than in carriers (52:19 versus 19:61, respectively; P < 0.0001), probably reflecting a higher incidence of HTLV-1 infection in females and a higher incidence of development of ATL in males. We found that the frequency of the TNF-alpha-857T allele, reported to be associated with high transcriptional activity of the promoter/enhancer region of the TNF-alpha gene, was enriched in individuals with ATL compared with healthy carriers (18.3% versus 8.8%, respectively; odds ratio, 2.34; 95% confidence interval, 1.2-4.7). None of the other four TNF-alpha polymorphisms was a significant indicator of risk of development of ATL, although odds ratios (ATL versus carrier) of all of the TNF-alpha polymorphisms were higher than 1.0. Furthermore, analysis of polymorphisms for GSTM1, GSTT1, CYP1A1, and BCL2 showed no significant difference between ATL patients and healthy carriers. Genetic polymorphism leading to increased TNF-alpha production may enhance susceptibility to ATL among HTLV-1 carriers. Alternatively, but less likely, the HLA loci might be an important factor because the TNF-alpha gene lies within the class III region of the MHC; however, the 857T allele is not in linkage disequilibrium with HLA alleles associated with ATL development.

Allelotype analysis of childhood acute lymphoblastic leukemia.

To identify the genetic events that may play an important role in leukemogenesis of childhood ALL, we report for the first time the allelotyping of childhood ALL. Twenty-four cases of childhood ALL were screened for loss of heterozygosity (LOH) using 101 highly polymorphic microsatellite markers, which are distributed among all autosomal chromosomes. For LOH analysis on both chromosomes 9 and 12, 54 childhood ALL samples were examined. The most frequent allelic loss was found on chromosomal arm 9p, where 20 of 50 (40%) informative samples showed LOH. Moreover, nearly 30% of samples that did not have either homozygous deletions or point mutations of the putative tumor suppressor genes CDKN2/INK4A/p16 and INK4B/p15 on chromosomal arm 9p had LOH at D9S171. Loss of chromosomal arm 12p was also frequent (26%). Mutational analysis suggested that the altered gene on 12p is not the cyclin-dependent kinase inhibitor p27/Kip1, which is also on 12p. Several other regions that had LOH included 1p, 4q, 5p, 6q, 7p, 8p, 9q, 10q, 13q, 17p, 17q, 18q, 19q, and 22q. Of 24 patients, 19 (79%) showed allelic loss on at least one chromosomal arm. Samples of two patients (8%) showed LOH on almost all chromosomes. Fractional allelic loss, calculated for each sample as the total number of chromosomal arms lost/total number of arms with information, showed a median value of 0.04 and a mean of 0.123 (range, 0 to 0.95). This fractional allelic loss is lower than those reported for many solid tumors. This analysis shows the extreme power of LOH analysis using microsatellite markers in childhood ALL.

Frequent loss of heterozygosity in region of the KIP1 locus in non-small cell lung cancer: evidence for a new tumor suppressor gene on the short arm of chromosome 12.

To refine the chromosomal localization of a putative tumor suppressor gene, we analyzed the loss of heterozygosity (LOH) of chromosome 12 in 36 primary non-small cell lung cancer (NSCLC) samples with matched normal DNA using 22 highly informative polymorphic markers. Twelve cases showed LOH at one or more loci on chromosome 12. LOH of chromosome arm 12p was more frequent in large cell carcinoma than squamous cell carcinoma, indicating molecular genetic heterozygosity within the major NSCLC subtypes. We identified the smallest commonly deleted region on chromosome 12p13. This region is flanked by D12S269 and D12S308, including the KIP1 gene. Mutational analysis of KIP1 using PCR-single strand conformation polymorphism and Southern Blot analysis showed no homozygous deletions, rearrangements, or point mutations, suggesting that the altered gene in this region is not the KIP1 gene. These data suggest that a new tumor suppressor gene which is involved in tumorigenesis of NSCLC is in the region of KIP1.

Molecular analysis of the cyclin-dependent kinase inhibitor gene p27/Kip1 in human malignancies.

Cyclin and cyclin-dependent kinase (CDK) complexes play important roles in controlling the cell cycle. The CDK inhibitors (CDKIs) inhibit the kinase activities of the complexes and block transitions of the cell cycle. Recently several CDKI genes have been cloned, and evidence suggests that at least a couple of these may be tumor suppressor genes. In this study, the partial structure of a CDKI gene, p27/Kip1, was determined. In addition, a large number of human cancers (432 cases) and cancer cell lines (20 lines) were analyzed for alterations of the p27/Kip1 gene by Southern blot analysis and PCR/single-strand conformation polymorphism. The coding region of the p27/Kip1 gene consists of at least two exons and an intron of about 600 bp. In 140 tumors of various tissues and 18 transformed cell lines, no deletions or rearrangements of the gene were detected by Southern blot analysis using a part of the coding sequence as a probe. One polymorphism and one silent mutation were detected by PCR/single-strand conformation polymoprhism. The polymorphism was a nucleotide substitution of guanine for thymine (GTC-->GGC) at codon 109, resulting in an amino acid substitution of glycine for valine (Val-->Gly). In summary, no abnormalities of the p27/Kip1 gene were detected in human malignancies. Now, two groups of CDKIs are classified based on the structure of the proteins. One group includes the p15, p16, and p18 CDKIs, which have ankyrin repeat motifs. The p15 and p16 CDKI genes are very frequently mutated in a variety of cancers. The p27/Kip1 and p21 CDKIs belong to the other group. We reported previously that abnormalities of the p21 gene were very rare. The latter group of the CDKIs, including p27/Kip1 and p21, are rarely mutated in human malignancies.

Scaling law for electrocaloric temperature change in antiferroelectrics.

A combination of theoretical and first-principles computational methods, along with experimental evidence from the literature, were used to predict the existence of a scaling law for the electrocaloric temperature change in antiferroelectric materials. We show that the temperature change scales quadratically with electric field, allowing a simple transformation to collapse the set of ΔT(E) onto a single curve. This offers a unique method that can be used to predict electrocaloric behavior beyond the limits of present measurement ranges or in regions where data are not yet available.

Integration of SV40 in human osteosarcoma DNA.

Simian virus 40 (SV40) has been demonstrated in several types of tumors, including osteosarcoma, by polymerase chain reaction (PCR). We detected SV40 sequences by PCR, followed by hybridization, in nine of 35 osteosarcoma tumors and one of 11 osteosarcoma explants. PCR can detect fewer than one virus per cell but gives little detail of the gross structure and abundance of the virus. Analysis by Southern blotting of total DNA from ten osteosarcomas, positive for SV40 by PCR, found viral integration in half of these. Analysis showed integration of one to four copies per cell of rearranged SV40. No SV40 was detectable on blots of the remaining five SV40+ osteosarcomas, perhaps because of the lesser sensitivity of direct hybridization. Inactivation of the p53 and Rb tumor suppressors is a key activity of SV40 T-antigen. Unexpectedly, correlation of these findings with our prior studies indicated that five of ten osteosarcomas positive for SV40 DNA had mutations of p53, and two had deleted Rb. Apparently clonal integration with pre-existing alteration of a tumor suppressor gene, suggests that SV40 may play a role in the final conversion to malignant osteosarcoma.