Genetic constraints on floral evolution: a review and evaluation of patterns

The characteristics of flowers influence most aspects of angiosperm reproduction, including the agents of pollination and patterns of mating. Thus, a clear view of the forces that mediate floral phenotypic evolution is central to understanding angiosperm diversity. Here, we inform on the capacity for floral phenotype to respond to selection by reviewing published data on heritabilities and genetic correlations for several classes of floral traits (primary sexual, attraction, mating system) in hermaphroditic plants. We find significant heritability for all floral traits but also variation among them, as well as a tendency for heritability to vary with mating system, but not life history. We additionally test predictions stemming from life history theory (eg, negative covariation between male-female traits and flower size-flower number), and ideas concerning the extent and pattern of genetic integration between flowers and leaves, and between the sexes of dioecious and gynodioecious species. We find mixed evidence for life history tradeoffs. We find strong support for floral integration and its relation with floral morphology (actinomorphy vs zygomorphy) and for a decoupling of floral and vegetative traits, but no evidence that modular integration varies with floral morphology. Lastly, we find mixed evidence for a relationship between the level of sexual dimorphism in attraction traits and the between-sex correlation in gender dimorphic plants.     

Hypertensive disease in twin pregnancies: a review.

Reports over the past seventy years show that twin gestations lead to an increased risk of hypertensive disorders. Numerous studies discuss the incidence of hypertensive disease in twin versus singleton gestations, as well as effects of parity, race, age, income level, smoking, zygosity and heritability on this condition. The range of relative risk of gestational hypertension, preeclampsia and eclampsia for twin compared to singleton gestations is 1.2 to 2.7, 2.8 to 4.4 and 3.4 to 5.1 respectively. Parity, African-American ethnicity, and young maternal age are all factors that increase the relative risk of acquiring hypertensive disease to 4.0, 1.8 and 1.5 in mothers of twin gestations. Factors such as maternal smoking, income level and zygosity have a negligible effect on the relative risk of acquiring hypertensive disease in twin gestations. In addition to twin mothers exhibiting a higher incidence of hypertensive disease compared to their singleton counterparts, they also exhibit an earlier onset of hypertensive disease at both 35 and 37 weeks of gestation comparatively. Uric acid levels measured at 30-31 weeks of gestation in twin mothers predicted the onset of preeclampsia with a sensitivity of 73% and a specificity of 74%. The range of risks presented in the literature is wide and the therapies avocated are diverse. We therefore decided to summarize the risks in a comparative fashion and to review current therapeutic strategies for the convenience of clinicians who confront increasing numbers of multiple pregnancies. The tables bring all recent published risks together in the first comparative analysis in which the data has been converted to relative risks and confidence intervals. Because the literature is relatively silent on specific management of hypertensive disease in twin pregnancies, general management recommendations for singleton gestations should be used by practitioners caring over twin gestations.     

Life-history patterns in British Umbelliferae: a review

British Umbelliferae form a natural cohesive taxon, having patterns of habitat distribution, reproductive biology and life-history that distinguish them from other British dicotyledons. They are usually found in open sites, and are local or rare in distribution.
Almost half of British species have the andromonoecious sex habit. Perfect flowers are usually protandrous. The floral composition of umbels, and the pattern of opening of the inflorescence combine to produce a protogynous effect. These have been interpreted as mechanisms which decrease competition for resources between male and female functions in the plant, such that separate maternal and paternal fitness can become optimal.
Seeds often require a chilling treatment, alternating temperatures, or a period of after-ripening before they are capable of germination. Schizocarps are of low weight. This seems to relate to the relative openness of habitat wherein unbellifers are found. Patterns of dry matter distribution reflect the life-history strategies of various umbellifer species. Agromyzid leaf miners parasitize the more widespread species, and those which arc found in a greater number of different habitats.     

Life-history patterns in British Umbelliferae: a review

British Umbelliferae form a natural cohesive taxon, having patterns of habitat distribution, reproductive biology and life-history that distinguish them from other British dicotyledons. They are usually found in open sites, and are local or rare in distribution. Almost half of British species have the andromonoecious sex habit. Perfect flowers are usually protandrous. The floral composition of umbels, and the pattern of opening of the inflorescence combine to produce a protogynous effect. These have been interpreted as mechanisms which decrease competition for resources between male and female functions in the plant, such that separate maternal and paternal fitness can become optimal. Seeds often require a chilling treatment, alternating temperatures, or a period of after-ripening before they are capable of germination. Schizocarps are of low weight. This seems to relate to the relative openness of habitat wherein unbellifers are found. Patterns of dry matter distribution reflect the life-history strategies of various umbellifer species. Agromyzid leaf miners parasitize the more widespread species, and those which are found in a greater number of different habitats.     

Genetic disorders in beef cattle: a review

The main purpose of present review is to describe and organize autosomal recessive disorders (arachnomelia, syndactylism, osteopetrosis, dwarfism, crooked tail syndrome, muscular hyperplasia, glycogen storage disease, protoporphyria), which occur among beef cattle, and methods that can be applied to detect these defects. Prevalence of adverse alleles in beef breeds happens due to human activity—selections of favorable features, e.g. developed muscle tissue. Unfortunately, carriers of autosomal recessive diseases are often characterized by these attributes. Fast and effective identification of individuals, that may carry faulty genes, can prevent economical losses.     

Genetic variation in natural populations: patterns and theory.

Allozymic variation in natural populations of plants, animals, and humans based on studies published prior to early 1976 and involving 243 species, in which 14 or more loci were tested, is herein reviewed. Explanatory models are compared and contrasted in view of the evidence to see which theories best explain genetic variation in natural populations. The analysis suggests that the amounts of genetic polymorphism and heterozygosity vary nonrandomly between loci, populations, species, habitats, and life zones, and are correlated with ecological heterogeneity. Natural selection, in some form, may often be the major determinant of genetic population structure and differentiation. Yet precise critical experiments must be designed to test possible alternative hypotheses, to establish direct cause-effect relationships between ecological and genetic profiles, and to assay the contribution of single and multilocus structures to fitness.     

Effects of contaminants on genetic patterns in aquatic organisms: a review.

There is increasing awareness of the need to evaluate the effects of contaminants at the population level. Genetic techniques offer a powerful approach to assess contaminant-induced changes in populations. Yet studies to date are relatively few and not always carefully designed to maximize the utility inherent in this approach. We present a summary of contemporary genetic assessment methods and a review of published studies of genetic effects in field-exposed aquatic organisms. We discuss evaluations of genetic patterns that use genetic adaptation, allozyme variation, and molecular genetic (DNA) variation. Direct tests of genetic adaptation are very effective in establishing a concrete, and potentially deleterious population-level effect of contaminant exposure, but they are difficult to accomplish with most field-exposed organisms. Allozyme surveys are relatively simple and common, and may provide data that are suggestive of contaminant effects. However, these are rarely conclusive, primarily because few allozyme loci are variable and these few loci represent extremely small portions of the genome. Molecular genetic techniques have the potential to be very effective. But, there is a tendency to emphasize the power of the techniques, rather than the underlying causes of the molecular genetic patterns observed. The strength of the conclusions of each study varies widely, partially derived from variation in the strength of the techniques. We caution that all these approaches are greatly improved by careful experimental design that includes adequate numbers of reference and contaminated sites and sample size. In addition, careful exposure assessment is required, including site and tissue chemistry, biomarker responses, and measures of potentially deleterious effects, such as DNA damage, or reduced reproductive output or survival.     

Hodgkin's disease derived cell lines: a review.

A number of so-called "HD cell lines" have been established over the last 10-15 years (Table 1). Or those 15 cell lines we studied, only the cell lines CO, DEV, HD-70, HDLM, KM-H2, L-428, L-540 and SUP-HD1 can be regarded to represent true HD cell lines. According to the immunostaining results and molecular genetic data, these 8 cell lines can be assigned either to the T-cell lineage (CO, HDLM, L-540) or B-cell lineage (DEV, HD-70, KM-H2, SUP-HD1). With the data currently available, the cell lineage origin of L-428 cannot be unequivocally determined, but appears to be lymphoid. All but one of these eight HD cell lines have been established from patients with the nodular sclerosis subtype. Therefore, the conclusions drawn from the in vitro studies are limited to this histological subtype of HD. It is conceivable that culture conditions select for a particular type of cell that will survive. The state of differentiation of these HD cell lines remains unclear due to the incomplete expression of T- or B-cell antigens. The in vitro cells and the in vivo H-RS cells share, however, the expression of the unique activation markers CD15, CD25, CD30, CD71 and HLA-DR. Recently published data indicate that the HD cell lines express and produce a large number of cytokines. Multiple non-random chromosomal abnormalities and the expression of various proto-oncogenes are also new and exciting findings and certainly deserve further study. In summary, although the cultured cells are not unequivocally proven to be the direct progeny of in vivo H-RS cells, several continuous HD cell lines have been established that display a variety of phenotypical features identical or similar to those of their presumed in vivo counterparts. Surface marker, molecular genetic and other features suggest a T- or B-cell derivation. An extrapolation of these conclusions would point to a lymphoid origin of H-RS cells. Whether H-RS cells can originate from other cell types such as monocytes/macrophages or reticulum cells, cannot be answered with the currently available HD cell lines.     

Genetic counselor training: a review and considerations for the future.

The first training program for genetic counselors began in 1969. Since then a number of other programs have been developed and more than 650 individuals have graduated from these programs. This article reviews the development and current status of training opportunities for genetic counselors. Twelve programs that currently grant a master's-level degree in genetic counseling are reviewed. Other areas, such as certification and licensure, that reflect genetic counseling training or such issues of professional growth as continuing education and career advances are addressed.     

Genetic analysis of dermatoglyphic patterns in twins.

Analysis of variance was performed on 71 dermatoglyphic variables in 424 twin sets. Using a method of twin analysis estimates of genetic variance were obtained. 54 of the variables were quantitated using a scoring system with modifications of arch or no pattern = 0, loops = 1, whorl = 2. The results indicated a significant genetic influence in most pattern areas. Patterning was more genetically controlled in the hand than in the foot. The hallucal area had the most significant genetic component of the foot while the patterns in the thumb had nonsignificant components of genetic variance. The thumb deviated from patterning in the rest of the fingers and may be more closely related to big-toe patterning.     

Non-surgical management of peripheral vascular disease: a review.

Although the outlook for a pronounced improvement in the ischaemic limb that cannot be surgically treated remains bleak, cessation of smoking, encouragement of exercise, and the withdrawal of vasoconstricting agents may give some symptomatic relief. There is little evidence that vasodilators or antiplatelet agents have much to offer.     

Genetic marker patterns and endogenous mammary tumor virus genes in inbred mouse strains of Japan

In order to establish the genetic relatedness of the inbred mouse strains kept in Nara, genetic marker patterns were determined in conjunction with a study on endogenous mammary tumor viral genes in these strains. Isoenzyme patterns combined with patterns of other genetic markers, show that the unrelatedness between various inbred strains of the dd stock is as high or even higher as between strains of known different origin and geneology. Based on endogenous viral gene patterns the dd stock derived mice can be subdivided into three group, DDD, DDN, DDO, KF and DD/Tbr. The DD/Tbr and its foster-nursed substrain (DD/Tbrf) have the lowest number of endogenous viral genes, i.e. two, while the other strains carry 4-6 such genes. The SLN and SHN strains, derived from a Swiss stock, have a similar pattern of viral genes different that of all other strains studied, also strains of Swiss origin from other sources, such as the NFS and the GR.     

Dynamic hematological disease: a review

We review the basic characteristics of four periodic hematological disorders (periodic auto-immune hemolytic anemia, cyclical thrombocytopenia, cyclical neutropenia and periodic chronic myelogenous leukemia) and examine the role that mathematical modeling and numerical simulations have played in our understanding of the origin of these diseases and in the regulation of hematopoiesis.     

Genetic factors in iodine deficiency disorders: a general review

This review presents a summary of what is known about genetic factors possibly involved in iodine deficiency disorders. After an overview on thyroid iodine metabolism and the role of environmental factors in endemic goitre, we analyse genetic studies on endemic goitre reported in the literature. We hypothesize that endemic goitre is a multifactorial disease in which the major factor would be of environmental nature (iodine deficiency) with a lesser role for genetic factors. Mutations, in a heterozygote state, of one of the genes involved in tiered hormonogenesis could lead to a less effective metabolic pathway in the iodine transport or hormonogenesis. We also briefly review various hereditary disorders which may be involved in endemic goitre. Then, we postulate that the presence of some genetic variants in the population or the heterozygote status of individuals for thyroid hereditary disorders may influence the degree of the thyroid enlargement and/or hypothyroidism.     

Huntington's disease: a clinical review

Huntington disease (HD) is a rare neurodegenerative disorder of the central nervous system characterized by unwanted choreatic movements, behavioral and psychiatric disturbances and dementia. Prevalence in the Caucasian population is estimated at 1/10,000-1/20,000. Mean age at onset of symptoms is 30-50 years. In some cases symptoms start before the age of 20 years with behavior disturbances and learning difficulties at school (Juvenile Huntington's disease; JHD). The classic sign is chorea that gradually spreads to all muscles. All psychomotor processes become severely retarded. Patients experience psychiatric symptoms and cognitive decline. HD is an autosomal dominant inherited disease caused by an elongated CAG repeat (36 repeats or more) on the short arm of chromosome 4p16.3 in the Huntingtine gene. The longer the CAG repeat, the earlier the onset of disease. In cases of JHD the repeat often exceeds 55. Diagnosis is based on clinical symptoms and signs in an individual with a parent with proven HD, and is confirmed by DNA determination. Pre-manifest diagnosis should only be performed by multidisciplinary teams in healthy at-risk adult individuals who want to know whether they carry the mutation or not. Differential diagnoses include other causes of chorea including general internal disorders or iatrogenic disorders. Phenocopies (clinically diagnosed cases of HD without the genetic mutation) are observed. Prenatal diagnosis is possible by chorionic villus sampling or amniocentesis. Preimplantation diagnosis with in vitro fertilization is offered in several countries. There is no cure. Management should be multidisciplinary and is based on treating symptoms with a view to improving quality of life. Chorea is treated with dopamine receptor blocking or depleting agents. Medication and non-medical care for depression and aggressive behavior may be required. The progression of the disease leads to a complete dependency in daily life, which results in patients requiring full-time care, and finally death. The most common cause of death is pneumonia, followed by suicide.