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PubMed2003

Somatization among older primary care attenders.

BACKGROUND: The importance of somatization among older primary care attenders is unclear. We aimed to establish the prevalence, persistence and associations of somatization among older primary care attenders, and the associations of frequent attendance. METHOD: One hundred and forty primary care attenders over 65 years were rated twice, 10 months apart, on measures of somatization, psychiatric status, physical health and attendance. RESULTS: The syndrome of GMS hypochondriacal neurosis had a prevalence of 5% but was transient. Somatized symptoms and attributions were persistent and associated with depression, physical illness and perceived poor social support. Frequent attenders (top third) had higher rates of depression, physical illness and somatic symptoms, and lower perceived support. CONCLUSION: Somatization is common among older primary care attenders and has similar correlates to younger primary care somatizers. Psychological distress among older primary care attenders is associated with frequent attendance. Improved recognition should result in benefits to patients and services.

Aged↗
PubMed2005

Accuracy of diagnosing depression in primary care: the impact of chronic somatic and psychiatric co-morbidity.

BACKGROUND: Depression is highly co-morbid with both psychiatric and chronic somatic disease. These types of co-morbidity have been shown to exert opposite effects on underdiagnosis of depression by general practitioners (GPs). However, past research has not addressed their combined effect on underdiagnosis of depression. METHOD: Co-morbidity data on 191 depressed primary-care patients selected by a two-stage sampling procedure were analysed. Diagnoses of major depression and/or dysthymia in the last 12 months were assessed using a standardized psychiatric interview (CIDI) and compared with depression diagnoses registered by GPs in patient contacts during the same period. Presence of psychiatric and chronic somatic co-morbidity was determined using the CIDI and contact registration, respectively. RESULTS: Regression analysis showed a significant interaction effect between psychiatric and chronic somatic co-morbidity on GPs' diagnosis of depression, while taking into account the effects of sociodemographic variables, depression severity and number of GP contacts. Subsequent stratified analysis revealed that in patients without chronic somatic co-morbidity, a lower educational level, a less severe depression, and fewer GP contacts all significantly increased the likelihood of not being diagnosed as depressed. In contrast, in patients with chronic somatic co-morbidity, only having no psychiatric co-morbidity significantly decreased the likelihood of receiving a depression diagnosis. CONCLUSIONS: Our results indicate that the effects of psychiatric co-morbidity and other factors on underdiagnosis of depression by GPs differ between depressed patients with and without chronic somatic co-morbidity. Efforts to improve depression diagnosis by GPs seem to require different strategies for depressed patients with and without chronic somatic co-morbidity.

Adolescent↗
PubMed1997

A comparison between somatic symptoms with and without clear organic cause: results of an international study.

BACKGROUND: The aim of this study was to determine differences between patients attending primary-care clinics with somatic symptoms for which no organic cause can be found, and those with a clear organic basis for their complaints. METHODS: Physical and psychiatric morbidity was measured in 5447 subjects presenting for primary care in 14 countries. Subjects were recruited using a two-stage design from 26,969 consecutive attenders and 25,916 (96.5%) subjects were successfully screened using the General Health Questionnaire (GHQ-12). The response rate for the second-stage assessment was 63% and consisted of the Composite International Diagnostic Instrument adapted for use in primary care (CIDI-PHC), the 28-item GHQ, the Groningen Social Disability Schedule (GSDS) and GP ratings to assess physical psychiatric and social status. Patients who reached the threshold for the number of somatic symptoms (five or more symptoms) were then divided into two groups on the basis of whether their somatic symptoms were medically explained or not. RESULTS: The presence of somatic symptoms, irrespective of aetiology, was associated with increased social and psychiatric morbidity. In the case of non-medically explained symptoms there was a clear linear relationship while with medically explained symptoms psychiatric morbidity rose sharply in the presence of more than 11 symptoms. Patients who had five or more non-medically explained symptoms were significantly younger, had greater psychiatric morbidity, were at greater risk of harmful use of alcohol and reported greater social disability than those with a medical explanation for their somatic symptoms. Patients who had an excess of somatic symptoms in both categories had especially high rates of social and psychiatric morbidity. CONCLUSIONS: These results show a strong association between somatic symptoms irrespective of aetiology and psychiatric morbidity across disparate cultures.

Adolescent↗
PubMed2000

The genetic aetiology of somatic distress.

BACKGROUND: Somatoform disorders such as neurasthenia and chronic fatigue syndrome are characterized by a combination of prolonged mental and physical fatigue. This study aimed to investigate the heritability of somatic distress and determine whether this dimension is aetiologically distinct from measures of depression and anxiety. METHOD: Measures of anxiety, depression, phobic anxiety, somatic distress and sleep difficulty were administered in a self-report questionnaire to a community-based sample of 3469 Australian twin individuals aged 18 to 28 years. Factor analysis using a Promax rotation, produced four factors: depression, phobic anxiety, somatic distress and sleep disturbance. Multivariate and univariate genetic analyses of the raw categorical data scores for depression, phobic anxiety and depression were then analysed in Mx1.47. RESULTS: Univariate genetic analysis revealed that an additive genetic and non-shared environmental (AE) model best explained individual differences in depression and phobic anxiety scores, for male and female twins alike, but could not resolve whether additive genes or shared environment were responsible for significant familial aggregation in somatic distress. However, multivariate genetic analysis showed that an additive genetic and non-shared environment (AE) model best explained the covariation between the three factors. Furthermore, 33 % of the genetic variance in somatic distress was due to specific gene action unrelated to depression or phobic anxiety. In addition, 74% of the individual environmental influence on somatic distress was also unrelated to depression or phobic anxiety. CONCLUSION: These results support previous findings that somatic symptoms are relatively aetiologically distinct both genetically and environmentally from symptoms of anxiety and depression.

Adolescent↗
PubMed1999

The natural history of somatization in primary care.

BACKGROUND: Somatization is often regarded as a chronic disorder. However, empirical studies to support this view and to determine its natural history in primary care are lacking. This paper provides data on the incidence and persistence of current somatization syndrome in a large cross-national sample drawn from 15 sites in 14 countries. METHODS: After screening with the General Health Questionnaire, a stratified sample of 5438 primary care patients was interviewed with the Composite International Diagnostic Interview and evaluated for physical health status, self-rated overall health and for occupational disability. Twelve months later, 3204 of the patients completed follow-up interviews. RESULTS: Over a 12-month period, an abridged form of somatization defined as four current symptoms in males and six in females was persistent in 45.9% of the patients. Persistence of syndrome was related to age and to subjective indices of psychological distress at baseline. Persistence was unrelated to depression. The 12-month incidence of the abridged somatization syndrome was 7.1% (95% CI, 6.1-8.3%). Individuals with depression at baseline and those with poor view of their health were more likely to develop new episodes of somatization 12-months later. CONCLUSION: Somatization syndrome showed considerable change over time. Persistence and onset of somatization were related to both level of psychopathology and health beliefs.

Adolescent↗
PubMed1991

Angiotensin-converting enzyme: zinc- and inhibitor-binding stoichiometries of the somatic and testis isozymes.

The blood pressure regulating somatic isozyme of angiotensin-converting enzyme (ACE) consists of two homologous, tandem domains each containing a putative metal-binding motif (HEXXH), while the testis isozyme consists of just a single domain that is identical with the C-terminal half of somatic ACE. Previous metal analyses of somatic ACE have indicated a zinc stoichiometry of 1 mol of Zn2+/mol of ACE and inhibitor-binding studies have found 1 mol of inhibitor bound/mol of enzyme. These and other data have indicated that only one of the two domains of somatic ACE is catalytically active. We have repeated the metal and inhibitor-binding analyses of ACE from various sources and have determined protein concentration by quantitative amino acid analysis on the basis of accurate polypeptide molecular weights that are now available. We find that the somatic isozyme in fact contains 2 mol of Zn2+ and binds 2 mol of lisinopril (an ACE inhibitor) per mol of enzyme, whereas the testis isozyme contains 1 mol of Zn2+ and binds 1 mol of lisinopril. In the case of somatic ACE, the second equivalent of inhibitor binds to a second zinc-containing site as evidenced by the ability of a moderate excess of inhibitor to protect both zinc ions against dissociation. However, active site titration with lisinopril assayed by hydrolysis of furanacryloyl-Phe-Gly-Gly revealed that 1 mol of inhibitor/mol of enzyme abolished the activity of either isozyme, indicating that the principal angiotensin-converting site likely resides in the C-terminal (testicular) domain of somatic ACE and that binding of inhibitor to this site is stronger than to the second site.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1983

Distinguishing between cognitive and somatic trait and state anxiety in children.

The study was conducted to develop self-report measures of cognitive and somatic trait and state anxiety for children and to evaluate the utility of distinguishing between cognitive and somatic anxiety. Sixty-seven fourth grade children anticipated and then performed a mathematics task either in a high- or low-stress condition. While the children anticipated performing the task, measures of seven cognitive behaviors were obtained by means of both a think aloud procedure and a questionnaire. The results of the study indicated that reliable trait and state measures of cognitive and somatic anxiety were successfully developed. Further, the trait measures of cognitive and somatic anxiety were found to be relatively impervious to induced anxiety states. As expected, cognitive trait anxiety but not somatic trait or state anxiety was found to be related to task performance. High cognitive state and/or trait anxiety was found to be associated with more preoccupation and performance denigration as well as taking less of an analytic attitude toward the situation. Somatic trait and state anxiety were found to be associated with preoccupation. In general, the results support the construct validity of the measures developed and the utility of distinguishing between cognitive and somatic anxiety in children.

Achievement↗
PubMed2003

Clinical characteristics of somatization in dental practice.

OBJECTIVES: This study was a first attempt to derive an estimate of the likely incidence of somatization-specific behaviour in a dental setting and its relationship with both somatic symptoms and symptoms of depression. METHODS: Somatization-specific behaviour was operationalized as reporting of inexplicable dental symptoms (eg pain), remarkable frequent attendance at a dental surgery, inexplicably high treatment use or unreasonable requests with regard to treatment. RESULTS: Of the 309 patients surveyed, 8.7%o fulfilled one or more of the criteria for somatization-specific behaviour. This was particularly manifested by a high attendance rate (6.8%). Women exhibited somatization-specific behaviour significantly more often (73%) than men (27%9). Support was found for the hypothesis that individuals exhibiting characteristics of somatization-specific behaviour would present themselves to dentists more often with dental complaints and would suffer more from symptoms of depression than patients that did not display these characteristics. CONCLUSIONS: The results suggest that somatization is a factor in dental practice.

Adolescent↗
PubMed2004

Hemoglobin promotes somatic embryogenesis in peanut cultures.

Critical parameters influencing somatic embryogenesis include growth regulators and oxygen supply. Consequently, the present investigation has focused on optimization of a somatic embryogenic system for peanut (Arachis hypogaea L.) through media supplementation with the auxin, picloram. The latter at 30 mg L(-1) was optimal for inducing regeneration of somatic embryos from cultured explants of zygotic embryos. In contrast, somatic embryogenesis did not occur in the absence of this growth regulator. An assessment has also been made of the beneficial effect on somatic embryogenesis and plant regeneration of the commercial hemoglobin (Hb) solution, Erythrogen. Hemoglobin at 1:50 and 1:100 (v:v) stimulated increases in mean fresh weight (up to a maximum of 57% over control), mean number of explants producing somatic embryos (15%) and mean number of somatic embryos per explant (29%).

Arachis↗
PubMed1955

Sedimentation and viscosity studies on the capsular and somatic polysaccharides of pneumococcus Type III.

Sedimentation constants at infinite dilution have been found to be 1.89 and 4.06 for the somatic and capsular polysaccharides, respectively, from pneumococcus Type III. Intrinsic viscosities have been determined for the somatic and capsular polysaccharides of pneumococcus Type III using the Ostwald viscometer. Molecular weights and dimensions have been calculated for the somatic and capsular polysaccharides of pneumococcus Type III assuming the molecules to be prolate ellipsoids of revolution. Values for the somatic polysaccharide are: molecular weight, 26,400; diameter, 0.97 mmicro; and length, 36.18 mmicro. Values for the capsular polysaccharide are: molecular weight, 171,800; diameter, 1.04 mmicro; and length, 177.87 mmicro. The molecular weights were calculated for the somatic and capsular polysaccharides of pneumococcus Type III assuming the molecules to be flexible chains. The value of the molecular weight of the somatic polysaccharide is 31,500 and the value for the molecular weight of the capsular polysaccharide is 267,500. The molecules of both the somatic and capsular polysaccharides exhibit high degrees of asymmetry.

Polysaccharides↗
PubMed1999

Different mismatch repair deficiencies all have the same effects on somatic hypermutation: intact primary mechanism accompanied by secondary modifications.

Somatic hypermutation of Ig genes is probably dependent on transcription of the target gene via a mutator factor associated with the RNA polymerase (Storb, U., E.L. Klotz, J. Hackett, Jr., K. Kage, G. Bozek, and T.E. Martin. 1998. J. Exp. Med. 188:689-698). It is also probable that some form of DNA repair is involved in the mutation process. It was shown that the nucleotide excision repair proteins were not required, nor were mismatch repair (MMR) proteins. However, certain changes in mutation patterns and frequency of point mutations were observed in Msh2 (MutS homologue) and Pms2 (MutL homologue) MMR-deficient mice (for review see Kim, N., and U. Storb. 1998. J. Exp. Med. 187:1729-1733). These data were obtained from endogenous immunoglobulin (Ig) genes and were presumably influenced by selection of B cells whose Ig genes had undergone certain mutations. In this study, we have analyzed somatic hypermutation in two MutL types of MMR deficiencies, Pms2 and Mlh1. The mutation target was a nonselectable Ig-kappa gene with an artificial insert in the V region. We found that both Pms2- and Mlh1-deficient mice can somatically hypermutate the Ig test gene at approximately twofold reduced frequencies. Furthermore, highly mutated sequences are almost absent. Together with the finding of genome instability in the germinal center B cells, these observations support the conclusion, previously reached for Msh2 mice, that MMR-deficient B cells undergoing somatic hypermutation have a short life span. Pms2- and Mlh-1-deficient mice also resemble Msh2-deficient mice with respect to preferential targeting of G and C nucleotides. Thus, it appears that the different MMR proteins do not have unique functions with respect to somatic hypermutation. Several intrinsic characteristics of somatic hypermutation remain unaltered in the MMR-deficient mice: a preference for targeting A over T, a strand bias, mutational hot spots, and hypermutability of the artificial insert are all seen in the unselectable Ig gene. This implies that the MMR proteins are not required for and most likely are not involved in the primary step of introducing the mutations. Instead, they are recruited to repair certain somatic point mutations, presumably soon after these are created.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Tissue-specific somatic mosaicism in spinal and bulbar muscular atrophy is dependent on CAG-repeat length and androgen receptor--gene expression level.

The factors influencing the tissue-specific pattern of somatic mosaicism in CAG-repeat diseases have not yet been fully resolved. We performed a detailed analysis of the degree of somatic mosaicism in various tissues from 20 patients with spinal and bulbar muscular atrophy (SBMA), including 4 who were deceased. The most outstanding feature was the prominent somatic mosaicism observed in the cardiac and skeletal muscles, composed predominantly of postmitotic cells, and in the skin, prostate, and testis. The CNS tissues, liver, and spleen showed the least mosaicism. The tissue distribution of somatic mosaicism in patients with SBMA was markedly different from that in patients with Huntington disease (HD) and from that in patients with dentatorubral-pallidoluysian atrophy (DRPLA). The degree of somatic mosaicism correlated with the CAG-repeat number but not with age at examination. Furthermore, tissues with a higher mosaicism level corresponded well to those with a higher expression level of androgen receptor protein. The tissue-specific pattern of somatic mosaicism related not only to cell composition with different cell turnover rates but to repeat size and gene expression levels, and postnatal cell division is unlikely to be a major cause of somatic mosaicism probably because of the relative stability of CAG repeat in SBMA.

Adult↗
PubMed1998

The structure of depression among elderly institution residents: affective and somatic correlates of physical frailty.

BACKGROUND: Confounding of depression with somatic illness and anxiety, a problem in any age group, may be especially troublesome in frail older persons. This paper examined this problem in a factor analytic study of the structure of depressive symptomatology, identifying affective and somatic symptom clusters and relating those clusters to health and functional variables cross-sectionally and prospectively over a 1-year interval. METHODS: The factor structure of a DSM-IV symptom checklist was examined among 1,245 elderly long-term care residents. Regression analyses examined the association of resulting factors with cognition, functional disability, self- and physician-rated health, and pain at baseline and a year later. One-year mortality was also examined. RESULTS: Factor analysis revealed three unique symptom clusters: depressed mood, somatic symptoms, and psychic anxiety. Depressed mood and somatic symptoms were associated cross-sectionally with all functional health variables, but psychic anxiety was associated only with pain. Longitudinally, depressed mood was the only independent predictor of decline in cognition, functional ability, physician-rated health, and mortality; the last effect, however, did not withstand control for baseline health and functioning. Somatic symptoms at baseline predicted decrement in self-rated health a year later. Effects varied as a function of cognitive status. CONCLUSIONS: These data suggest that concerns about the confounding role of somatic symptoms in the association of depression with physical health are unfounded. Although somatic symptoms of depression and anxiety were associated with health and functional status cross-sectionally, depressed mood was by far the stronger predictor of health declines over time.

Aged↗
PubMed2003

Expression of Chia4-Pa chitinase genes during somatic and zygotic embryo development in Norway spruce (Picea abies): similarities and differences between gymnosperm and angiosperm class IV chitinases.

The developmental pathway of somatic embryogenesis in Norway spruce involves proliferation of proembryogenic masses (PEMs), PEM-to-somatic embryo transition and further development of the somatic embryos. It has previously been shown that extracellular signal molecules, including arabinogalactan proteins, lipo-chitooligosaccharides and chitinases, regulate somatic embryogenesis. The Chia4-Pa1 gene from Norway spruce is described here. The Chia4-Pa1 encodes a typical basic class IV chitinase, although the intron-exon organization of this gymnosperm chitinase is different from that in angiosperm class IV chitinases. The Chia4-Pa1 belongs to a small gene family with highly similar members, and the expression pattern of Chia4-Pa1 cannot be distinguished from that of other Chia4-Pa members. Upon withdrawal of plant growth regulators, i.e. during a treatment that stimulates PEM-to-somatic embryo transition and massive programmed cell death, a significant increase in transcription and translation of Chia4-Pa genes takes place. The expression pattern analysis revealed that Chia4-Pa genes are expressed in a subpopulation of proliferating cells and at the base of the somatic embryo. Furthermore, in seeds, Chia4-Pa genes are expressed in the megagametophyte in the single cell-layered zone surrounding the corrosion cavity. Taken together these results suggest that the Chia4-Pa expressing cells have a megagametophyte signalling function and that CHIA4-Pa stimulates programmed cell death and promotes PEM-to-somatic embryo transition.

Base Sequence↗
PubMed1992

Somatic and germline mutagenesis assayed by the unstable zeste-white test in Drosophila melanogaster.

This investigation is an attempt to compare mutation rates in germinal and somatic cells by the use of the unstable zeste-white assay in Drosophila melanogaster. In this system it is possible to use the same genetic end point to measure both somatic mutations (aberrantly pigmented spots in the eyes of adult flies) and germinal mutations (males with aberrantly pigmented eyes). We used two mutagens, formaldehyde and methylmethane sulphonate (MMS), to induce mutations and two different routes of mutagen administration, larval feeding and adult feeding, and scored mutations in somatic as well as germinal cells. Both types of tissues were susceptible to MMS mutagenesis, showing elevated frequencies of both germline mutations and eye spots. Formaldehyde, however, gave no increase in the germinal mutation rate but caused somatic mutations. These were found after larval exposure, but also among the offspring of exposed males, as formation of delayed somatic mutations. The results show that somatic cells are much more sensitive in monitoring induced mutations than germinal cells in this system. We also found that spontaneous mutation rate among germinal cells is 200 times higher than that in somatic cells, which presumably is due to the involvement of a mobile element.

Animals↗
PubMed2006

Relationship between genotoxicity biomarkers in somatic and germ cells: findings from a biomonitoring study.

A biomonitoring study to evaluate chromosome and DNA damage respectively in somatic and germ cells of a group of male workers exposed to styrene by using biomarkers of genotoxicity was carried out. Styrene-exposed workers from three different areas of Tuscany and healthy subjects, of comparable mean age, sex and lifestyle characteristics, as a control group not exposed to chemicals, have been enrolled. In addition to previous reports [L. Migliore, A. Naccarati, A. Zanello, R. Scarpato, L. Bramanti and M. Mariani (2002) Hum. Reprod., 17, 2912-2918; L. Migliore, A. Naccarati, F. Coppedè et al. (2006) Pharmacogenet. Genomics, 16, 87-99] we present now data on a cross-sectional investigation involving a homogeneous group of subjects for which data on both somatic and germ cells have been obtained from individuals (42 exposed and 25 controls). Somatic cell genotoxicity was assessed by analysing the frequency of micronucleated binucleated cells (MNBN) in blood lymphocytes. The micronucleus assay was coupled with centromeric fluorescence in situ hybridization (FISH) analysis. Primary DNA damage in germ cells was evaluated by alkaline single-cell gel electrophoresis (Comet assay) and the percentage of the tail DNA (%TD) was used as parameter of Comet evaluation. Moreover, to investigate the frequencies of aneuploidy and diploidy in sperm, we performed multicolour FISH, using DNA probes specific for the centromeric regions of sex chromosomes and chromosome 2, in decondensed sperm nuclei of samples with normal semen parameters in a subgroup of individuals. Mandelic and phenylglyoxylic acids (MAPGA) in end of shift samples were determined as biomarkers of internal dose. MAPGA excretion was consistent with an exposure to styrene above the threshold limit value-time weighted average concentration of 20 p.p.m. Styrene workers showed significantly higher frequency of MNBN as compared to controls (13.8 +/- 5.2 versus 6.2 +/- 5.1; P < 0.001), due to higher proportions of both micronuclei (MN) arising from chromosomal breakage (C-MN) and harbouring whole chromosomes (C+MN). DNA damage in sperm cells was also higher among styrene-exposed, the %TD being 11.02 +/- 2.99 versus 7.42 +/- 2.30 in controls (P < 0.001). The incidence of aneuploidy and diploidy for the tested chromosomes in sperm did not show a statistically significant difference between workers and controls. However, a positive correlation was found between genotoxic damage detected in somatic and in germ cells, even after removing the effect of age (r = 0.475; P < 0.001). Although cytogenetic biomarkers detected both in somatic and germ cells were interrelated, no relationships were apparent with exposure parameters. Styrene exposure may increase the likelihood of both chromosome and DNA damage in somatic and germ cells, thus supporting the hypothesis of an interference on reproductive capacity among exposed workers. This is the first time that a field study shows a correlation between two biomarkers of genotoxicity evaluated at the same time in somatic and germ cells.

Biomarkers↗
PubMed1998

Patterns of expression of the genes for glutamine synthetase isoforms during somatic and zygotic embryogenesis in carrot.

Three cDNA clones encoding isoforms of carrot glutamine synthetase (GS) were isolated and used as probes for analysis of the patterns of expression of the genes for GS isoforms during somatic embryogenesis and seed development in carrot. Transcripts corresponding to two of the cDNAs, CGS102 and CGS201, accumulated in both somatic embryos and developing seeds in the same manner. Their levels were high at the early stage of embryogenesis but decreased at the late stage. This pattern of expression is similar to the pattern of changes in GS activity observed during somatic embryogenesis. In contrast, expression of the transcript for another GS isoform detected with CGS103 cDNA was observed at the late stage of seed development and in senesced leaves but not in somatic embryos or young leaves. We also analyzed the levels of the transcripts in somatic embryos that had been cultured in media with either ammonium ions or glutamine as the nitrogen source. The amounts of the CGS102 and CGS201 transcripts fell when glutamine was supplied in the medium. These results indicated that GS activity was regulated at the transcriptional level and that the pattern of expression of the genes for GS during somatic embryogenesis reflected that during zygotic embryogenesis. It is possible that somatic embryogenesis and zygotic embryogenesis have common regulatory systems with respect to nitrogen metabolism.

DNA, Complementary↗
PubMed2006

Light quality treatments enhance somatic seedling production in three southern pine species.

Embryogenic cultures of loblolly pine (Pinus taeda L.), slash pine (Pinus elliottii Engelm.), longleaf pine (Pinus palustris Mill.) and slash pine x longleaf pine hybrids were initiated from immature seeds on an initiation medium containing 13.57 microM 2,4-dichlorophenoxyacetic acid and 2.22 microM benzylaminopurine. Embryogenic cultures proliferated and somatic embryos developed, matured and germinated following a modified protocol and media originally developed for radiata pine (Pinus radiata D. Don.) somatic seedling production. A discrete, light-sensitive pre-germination stage and a later germination (radicle emergence) stage were identified by the differential response of somatic embryos to light of different wavelengths. Different light quality treatments were applied during the pre-germination and germination steps, using cool white fluorescent bulbs or light-emitting diodes (LEDs), or both. In general, red wavelengths provided by LEDs during these steps resulted in higher frequencies of somatic embryo germination (up to 64%) and conversion (up to 50%), longer tap roots and more first-order lateral roots than the standard cool white fluorescent treatments or treatment with blue wavelengths from LEDs. In addition, exposure to red light allowed germination of somatic embryos of some clones that failed to produce germinants under fluorescent light. Germination and conversion were further enhanced by sequential application of cool white fluorescent light and red light, resulting in up to 100% germination and conversion in one experiment. Longleaf pine somatic embryos were especially responsive to the light quality treatments, resulting in the first report of somatic seedling production for this species.

2,4-Dichlorophenoxyacetic Acid↗