Lipid synthesis during morphogenesis of Mucor racemosus.

Lipid synthesis increases coordinately with protein and RNA synthesis during morphogenesis of Mucor racemosus. The lipid synthesis inhibitor cerulenin can completely block morphogenesis under conditions in which cell growth continues. An increase in phospholipid turnover may be an important correlate to morphogenesis of Mucor spp., especially the turnover of phosphotidyl inositol and phosphatidyl ethanolamine. The increase in ornithine decarboxylase, which occurs during morphogenesis, is inhibited by the addition of cerulenin.     

Lipid turnover during morphogenesis in the water mold Blastocladiella emersonii

The lipid content of $\text{Blastocladiella emersonii}$ zoospores is 5 pg/cell or about 13% of dry weight. Within the first few minutes of germination 60–70% of total zoospore lipid is lost, with neutral lipid, glycolipid and phospholipid fractions decreasing to about the same extent. These changes in lipid content precede the breakdown during germination of the complex and extensive membrane system of zoospores. During growth, which immediately follows germination, net phospholipid synthesis resumes so that total lipid is maintained at 6% of dry weight, but net synthesis of neutral and glycolipid does not begin until induction of sporulation. During sporulation the phospholipid level decreases so that the distribution of lipid among the three fractions approaches that found in zoospores. These changes in lipid content suggest that zoospore membranes containing neutral and glycolipids are synthesized $\text{de novo}$ during spore formation.     

Netrin-1/neogenin interaction stabilizes multipotent progenitor cap cells during mammary gland morphogenesis

Netrin-1 and its receptors play an essential role patterning the nervous system by guiding neurons and axons to their targets. To explore whether netrin-1 organizes nonneural tissues, we examined its role in mammary gland morphogenesis. Netrin-1 is expressed in prelumenal cells, and its receptor neogenin is expressed in a complementary pattern in adjacent cap cells of terminal end buds (TEBs). We discovered that loss of either gene results in disorganized TEBs characterized by exaggerated subcapsular spaces, breaks in basal lamina, dissociated cap cells, and an increased influx of cap cells into the prelumenal compartment. Cell aggregation assays demonstrate that neogenin mediates netrin-1-dependent cell clustering. Thus, netrin-1 appears to act locally through neogenin to stabilize the multipotent progenitor (cap) cell layer during mammary gland development. Our results suggest that netrin-1 and its receptor neogenin provide an adhesive, rather than a guidance, function during nonneural organogenesis.     

Lipid composition of three geographical sources of brine shrimp nauplii (Artemia sp.)

• 1.1. Percentage of triacylglycerols (TG), free fatty acids (FFA) and phospholipids (PL) in the total lipids, the fatty acid composition of each of these lipid classes, and the percentage of cholesterol were determined by gas chromatography in three geographical sources (San Francisco Bay, SFB; Chinese, CH; Colombian, COL) of brine shrim (Artemia sp.) nauplii.
• 2.2. There were no significant differences among sources of brine shrimp in total lipids, TG or FFA with means for all sources of 17.8, 65.8 and 10.9%, respectively. Percentage of phospholipid was significantly higher in SFB and CH sources of brine shrimp, 25.1 and 26.5%, respectively, than in COL 18.3%.
• 3.3. Marked differences in percentages of 18:3 (n-3) (linolenic acid) and 20:5 (n-3) (eicosapentaenoic acid or EPA) were found among brine shrimp sources, and concentration of these two fatty acids were usually inversely related within sources. The CH source contained higher concentrations of EPA ( > 9.0%) than the COL and SFB sources (< 5.0%) in all three lipid classes analyzed. No 22:6 (n-3) (docosahexaenoic acid or DHA) was found in any brine shrimp source.
• 4.4. Fatty acid compositions of the TG and PL were similar and did not differ among sources of brine shrimp, while the FFA had a lower percentage of polyunsaturated fatty acids, but was similar among sources of brine shrimp.
• 5.5. Differences in n-3 fatty acid composition indicated a difference in nutritional quality among sources of brine shrimp for feeding larval fish.

     

Lipid composition and fluidity of plasma membranes isolated from corn (Zea mays L.) roots

Although the results of lipid analyses from several plant species have been available for many years a complete characterization of the corn root plasma membrane is still lacking. The present study provides a detailed analysis of individual lipids and a characterization of the membrane fluidity of corn (Zea mays L.) root plasma membranes isolated by phase-partitioning. Phospholipids (43.9 mol%), sterols (40.8 mol%), and sphingolipids in the form of glucocerebroside (6.8 mol%) constitute the major lipid classes. Stigmasterol (19.8 mol%), campesterol (13.0 mol%), phosphatidylcholine 15.8 mol%), and phosphatidylethanolamine (14.2 mol%) represent the most ubiquitous individual lipids. Hydroxy fatty acids make up 80.9 mol% and very long chain fatty acids are almost 78% of fatty acids in glucocerebroside. Hydroxy arachidic acid (20:0 h) and hydroxy lignoceric acid (24:0 h) are most prominent and glucocerebroside from corn root plasma membranes contains virtually no unsaturated fatty acids. Among the phospholipids only phosphatidylserine displayed a high proportion of very long chain fatty acids (e.g., behenic and lignoceric acid). Membrane fluidity was estimated by fluorescence anisotropy. Due to the high sterol content the plasma membrane of corn roots is relatively rigid.     

In-vitro morphogenesis of corn (Zea mays L.)

The objective of this research was to study the in-vitro morphogenetic pattern of corn (Zea mays L.) shoot tips excised from aseptically-grown seedlings, and of expiants of axillary shoot buds, immature tassels and ears (staminate and pistillate inflorescences) obtained from greenhouse-grown corn plants. The seedling shoot tips and immature ears first regenerated clumps of multiple shoots within four weeks of culture on Murashige and Skoog (MS) basal medium supplemented with 500 mg/L casein hydrolysate (CH) and 9.0 M N⁶-benzyladenine (BA). Multiple shoot clumps were also differentiated from spikelets of immature tassels cultured on MS medium containing 500 mg/L CH, 4.5 M BA and 0.45 M 2,4-dichlorophenoxy acetic acid (2,4-D). All these multiple shoot clumps in turn differentiated clusters of ears after further four subcultures at four-week intervals under light on MS medium supplemented with 500 mg/L CH and 2.25, 4.5, 9.0 or 18 M BA. Axillary shoot buds readily differentiated clusters of ears within four weeks of the initial culture on these media. Secondary and tertiary ear clusters were initiated following subculture of primary ears on MS medium containing 500 mg/L CH and 4.5 or 9.0 M BA. Most of the ear primordia developed into ears with well-developed ovaries and styles on subculture on MS medium containing 500 mg/L CH and 1.0 M BA. Corn kernels were obtained after pollination of in-vitro-formed ears with pollens collected from greenhouse-grown corn. These kernels germinated in vitro and developed into mature corn plants in the greenhouse. Clusters of tassels were also differentiated in darkness from the multiple shoot clumps after six months successive subcultures but the spikelet primordia of tassels failed to develop fully under the in-vitro conditions tested. Somatic embryos arose directly from spikelet primordia of young tassels or ears on MS medium containing 500 mg/L CH and 4.5 M 2,4-D, or indirectly from calli derived from spikelets of young tassels and ears on MS medium containing 500 mg/L CH and 9.0 M 2.4-D.Abbreviations BA N⁶-benzyladenine - CH casein hydrolysate - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indole-3-butyric acid - MS Murashige and Skoog (basal medium) Heng Zhong is a Rockefeller Foundation Fellow on leave from the Institute of Botany, Academia Sinica, Beijing, P.R. China. This work was supported by a grant from the MidWest Plant Biotechnology Consortium and U.S.-A.I.D. grant No. DAN-4197-A-00-1126-00 to M.B. Sticklen. Thanks are due to Illinois Foundation Seeds, Champaign, USA for the supply of Honey N Pearl sweetcorn seeds and the Services of Center for Electron Optics, Michigan State University, for the electromicroscopic work as related to this publication.     

Variations in the chemical composition of Costaria costata during harvest

In this study, variations in the chemical composition of Costaria costata collected during 3 months of the harvest period were analyzed. Moisture (4.94–10.50 %), ash (29.25–38.19 %), protein (9.77–18.15 %), lipid (0.60–2.21 %), crude fiber (4.45–5.68 %), alginate (22.49–29.13 %), fucoxanthin (0.07–0.32 mg g^?1), polyphenol (1.579–4.796 mg g^?1) were analyzed from dried alga. Six mineral elements were analyzed and the most abundant were calcium (6.64–11.56 mg g^?1) and magnesium (7.02–7.92 mg g^?1). Analysis of fatty acid composition indicated that the polyunsaturated fatty acids palmitoleic acid and linoleic acid were abundant in May and June, whereas the saturated fatty acid palmitic acid was abundant in July. Amino acid composition was also analyzed and the most abundant amino acids were aspartic acid, glutamic acid, glycine, and alanine. The ratio of mannuronic acid to guluronic acid of alginate was 2.57, 2.17, and 1.66 in May, June, and July, respectively. The gel strength of alginate was 1,449.0, 1,935.0, and 980.5 g cm^?1 in May, June, and July, respectively. The results of this study indicate that C. costata is an excellent resource that provides extensively applications in the industrial areas of chemicals, food, cosmetics, and pharmacy.     

Lipid droplets in skeletal muscle during grass snake (Natrix natrix L.) development

Lipid droplets (LDs) are common organelles observed in Eucaryota. They are multifunctional organelles (involved in lipid storage, metabolism, and trafficking) that originate from endoplasmic reticulum (ER). LDs consist of a neutral lipid core, made up of diacyl- and triacylglycerols (DAGs and TAGs) and cholesterol esters (CEs), surrounded by a phospholipid monolayer and proteins, which are necessary for their structure and dynamics.Here, we report the protein and lipid composition as well as characterization and dynamics of grass snake (Natrix natrix) skeletal muscle LDs at different developmental stages. In the present study, we used detailed morphometric, LC-MS, quantitative lipidomic analyses of LDs isolated from the skeletal muscles of the snake embryos, immunofluorescence, and TEM.Our study also provides a valuable insight concerning the LDs' multifunctionality and ability to interact with a variety of organelles. These LD features are reflected in their proteome composition, which contains scaffold proteins, metabolic enzymes signalling polypeptides, proteins necessary for the formation of docking sites, and many others. We also provide insights into the biogenesis and growth of muscle LDs goes beyond the conventional mechanism based on the synthesis and incorporation of TAGs and LD fusion. We assume that the formation and functioning of grass snake muscle LDs are based on additional mechanisms that have not yet been identified, which could be related to the unique features of reptiles that are manifested in the after-hatching period of life, such as a reptile-specific strategy for energy saving during hibernation.     

Lipid composition of alveolar macrophage plasma membrane during postnatal development

This study was undertaken to define the age-related alterations in lipid composition that resident rabbit alveolar macrophages (AM) undergo during postnatal development. The eventual goal is to correlate these changes with the functional maturation of these cells. The number of AM recorded from total lung lavages rose markedly during the first 14 days of life, from 4.9 X 10(5) to 1.1 X 10(7). Adult lungs yielded 1.1 X 10(8) AM. A gradual but significant increase in fluorescence polarization (P) was observed during development when purified AM plasma membranes were tagged with the probe 1,6-diphenyl-1,3,5 hexatriene trimethyl ammonium. The rise ranged from a mean P value of less than or equal to 0.22 to 0.24 (p less than 0.001) for AM plasma membranes from rabbits 1- or 7-day-old to 30- or 150-day-old rabbits, respectively. This finding suggests that the fluidity of the AM plasma membrane decreased during postnatal development. Palmitic, stearic, oleic, and linoleic acids were the most prevalent fatty acids found in the neutral lipid fraction of the AM plasma membrane throughout development. The content of stearic acid rose from 10 to 16%, arachidonic acid rose from 2.8 to 9%, myristic acid decreased from 3.2 to 1.3%, palmitic acid decreased from 42 to 36%, and oleic and linoleic acids changed relatively little during the first 30 days of life. The levels of docosatetraenoic and docosapentaenoic increased gradually during the first 14 days of life, and by 30 days of life the levels declined to that observed at birth. The sum of these changes resulted in an increase in the ratio of unsaturated to saturated fatty acids (1 to 1.15) in the neutral lipid fraction. During the first month of life, the neutral lipid fatty acid pool in the total lipid fraction of AM plasma membrane increased from 12 to 18 mole %, cholesterol increased from 7 to 14 mole %, and total phospholipids decreased from 81 to 67 mole %. These changes resulted in increasing the cholesterol to phospholipid ratio from 0.09 at birth to 0.23 by 150 days of life. The levels of all three major lipid fractions were comparable at 30 days and 150 days of life. Adult levels of choline phosphoglycerides, the predominant phospholipid, were observed by 7 days of life to have decreased from 47 to 34.5 mole %, and the levels of ethanolamine phosphoglycerides and sphingomyelin increased from 17.5 to 25 mole % and from 9 to 13 mole %, respectively. Adult levels of lyso-bis-phosphatidic acid were reached by 30 days of life increasing from 8.2 to 17.8 mole %.(ABSTRACT TRUNCATED AT 400 WORDS)     

Variations of rat brown adipose tissue composition during cold acclimatization.

The modifications in weight and composition (lipids, proteins, water) of rat interscapular brown adipose tissue (BAT) were studied along the six first weeks of cold exposure and acclimatization. The variations of noreponephrine content was also investigated. During the first day of cold exposure, the major part of tissue lipids was released. During the following two days there was a fall in lipid and norepinehprine contents and uptake of water. Then, until the end of the first week a rapid repletion occurred. At that moment the relative pass of the tissue and the amounts of its principal components reached values which are not changed during the following weeks. We can conclude that the adaptative changes in the levels of BAT essential components are carried out at the end of the first week of cold exposure, long time before the non shivering thermogenesis is entirely effective.     

In vitro morphogenesis in Selaginella microphylla (Kunth.) Spring

Selaginella, an extant genus of primitive vascular plants, has survived over 400 million years of evolution. In vitro morphogenesis in Selaginella microphylla is considered for the first time to establish a well-documented aseptic culture on half- strength Murashige and Skoog’s basal medium with 2ip (4.92–49.21 μM), or Kn (4.65–46.47 μM) or GA₃ (2.89–28.90 μM) for shoot multiplication, and with different concentrations of IBA (4.9–49 μm) to initiate root cultures. GA₃ was instrumental for shoot multiplication as well as induction of reproductive structures in each and every leaf axil. On the other hand, it is observed that IBA alone in S. microphylla can act as signal molecules for induction of enormous numbers of root masses from a few existing roots. An interesting pattern of re-differentiation has also been observed where apical portions of large numbers of roots were converted to green shoot apical meristems. Further differentiation produced tiny green shoots. Distinct bipolarity was noted in shoots when they were isolated from root masses and appeared as embryo-like structures. Chromosome analysis from in vitro sporophytic plants revealed 2n = 16 chromosomes, indicating chromosomal stability. The interesting in vitro pattern of morphogenesis obtained in S. microphylla may provide new insights into totipotency of plants.     

Lipid content and fatty acid composition of the higher edible fungus--the oyster mushroom Pleurotus ostreatus (Fr.) Kummer

The content of free lipids in wild and cultivated plant bodies, as well as in the surface and deep mycelium of the higher edible basidiomycete Pleurotus ostreatus (Fr.) Kummer--Oyster mushroom--was studied. By means of GL chromatography fatty acids with the number of C atoms from 8 to 20 were identified. In plant bodies and mycelium of the Oyster mushroom unsaturated fatty acids preveil; the main portion falls to oleic acid (up to 56%).     

Interaction of ABRUPTUS/PINOID and LEAFY genes during floral morphogenesis in Arabidopsis thaliana (L.) Heynh

Analysis of interactions between mutations abruptus and leafy and previous data on interaction of abruptus with homeotic mutations apetala1, apetala2, and apetala3 showed that the functions of the ABRUPTUS/PINOID (ABR/PID) gene are as follows: (1) it directs pattern formation in inflorescence axis specifying the development either of floral meristem (FM) or of cauline leaves; (2) in concert with the leafy gene, it participates in the formation of FM; (3) it is involved in the determination and the formation of floral organ primordia in the first, second, and third whorls. Auxin accumulation in the abr mutant cells in callus culture was shown indicating the involvement of the ABR/PID gene in regulation of auxin efflux from cells. It is suggested that the ABR/PID expression in the sites of formation of FM and floral organs leads to local reduction in auxin level, which in turn, enhances expression of the LFY and homeotic genes responsible for FM formation and differentiation.     

Variations in rat liver chromatin composition during growth and the heterotic response

The manifestation of hybrid vigor with regard to the inheritance of body weight was established as a postweaning phenomenon in rats. Liver weight gain generally corresponded to body weight gain and also reflected hybrid vigor. The protein/DNA ratios of the chromatin from livers of inbred and heterotic hybrid male rats were found to increase with increasing age in growing rats. Hybrid chromatin had higher protein/DNA ratios throughout the age range studies. The difference between hybrids and inbreds were greatest in the early postweaning stages of growth and maturation. The RNA/DNA ratios of chromatin from livers of inbred and hybrid male rats were also found to exhibit trends within certain developmental periods.This investigation was supported by matching Federal and West Virginia State funds from the Hatch 190 grant and is published with the approval of the Director of the Agricultural Station as Scientific Paper No. 1293.     

Proximal and distal transformation during intercalary regeneration in the planarianDugesia(S)mediterranea

Summary Studies on intercalary regeneration in several organisms have shown that a regenerate is formed when surfaces of different positional value along the proximo-distal axis are opposed. One of the main problems posed by this phenomenon is to know which piece contributes to the building of the regenerate. In the present work we have studied this problem in planarians using chimaeras made between pieces of different body levels, irradiated or not, of the sexual and asexual races ofDugesia(S)mediterranea that differ in a chromosomal marker.The results found show very clearly that intercalary regenerates in planarians are formed by cells coming from both pieces (stumps), and that irradiated pieces keep the positional values and interact with non-irradiated pieces to restore the missing parts. This means that distal and proximal transformation do actually occur at the same time during intercalary regeneration in planarians. The implications of these results as regards to the origin of cells in the regenerate and to present models of intercalary regeneration are discussed.