Plant regeneration from mesophyll protoplasts of Matthiola incana (L.) R. Br.

Summary A protocol for obtaining regenerated fertile plants from mesophyll protoplasts of three lines of Matthiola incana is described. Protoplasts were isolated from leaves of 21–28 days old Matthiola plants grown in controlled environment. Sustained divisions were achieved when protoplasts were embedded in sodium alginate. Up to 2.0 % of the protoplasts developed into colonies which could be transferred to shoot regeneration media. More than 25 % of the obtained calluses regenerated shoots. About 4 % of these shoots could be rooted and after transfer to soil phenotypically normal plants have been obtained.Abbreviations 2,4-D 2,4-dichlorphenoxyacetic acid - NAA naphthalene acetic acid - IAA indole-3-acetic acid - BAP 6-banzylaminopurine - IPA isopentenyladenine - IPAR isopentenyladenosine - MES (2-[N-morpholino]) ethanesulfonic acid     

RS46(DXS548) genotyping of reproductive cells: approaching preimplantation testing of the fragile-X syndrome

In order to approach preimplantation testing for the fragile-X syndrome, we used genotyping of the polymorphic RS46(DXS548) locus closely linked to the FMR1 gene, in single reproductive cells of females. The RS46(DXS548) amplification was adjusted to the single cell level by a two-round polymerase chain reaction (PCR) procedure. Unfertilized oocytes and extruded polar bodies were subjected to PCR. RS46(DXS548) genotyping at the single cell level was successful in 95% of the samples. In two-third of the metaphase II oocytes and first polar bodies obtained from women who were heterozygous at the RS46(DXS548) locus, both maternal RS46(DXS548) alleles were observed because of crossing over during the first meiotic division. This makes gamete selection by first polar body analysis inefficient. From the allele frequencies found in 56 unrelated individuals, a heterozygote frequency of 51% was estimated, whereas the observed heterozygote frequency was 56%. The whole PCR procedure can be performed within 16 h after blastomere biopsy. Consequently, the selection and transfer of the diagnosed embryos can be carried out within an acceptable time. Therefore, preimplantation testing for the fragile-X syndrome with the RS46(DXS548) AC-repeat may be an alternative choice for prenatal testing for those carrier females who are heterozygous (informative) at the RS46(DXS548) locus.     

Age-dependent alterations of linoleic, arachidonic and eicosapentaenoic acids in renal cortex and medulla of spontaneously hypertensive rats

The lipid content as well as the fatty acid pattern of triglycerides, free fatty acids (FFA), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were estimated in renal cortex and medulla of spontaneously hypertensive rats (SHR) and normotensive Wistar rats (WR) at 4,8,26 and 52 weeks of age. In general, the level of triglycerides in renal medulla appeared higher when compared with the cortex. On the other hand, PC and PE, increasing with age, were usually higher in the cortex. A decreased percentage of linoleic acid (LA) in triglycerides, of arachidonic acid (AA) in PC and of eicosapentaenoic acid (EPA) in triglycerides, FFA, PC and PE could be found in the kidneys of SHR at 8 weeks of age, i.e. during the development of hypertension. This was accompanied with a rise of AA in FFA of SHR at 8 weeks of age, which occurred with delay in WR (at 26 weeks of age). From the data presented it can be concluded that systematic alterations in the availability of individual polyunsaturated fatty acids (PUFA) in various renal lipids might be related to the onset of hypertension in SHR which should be elucidated in more detail.     

Comments on “Seed germination as a thermobiological problem”

Summary In the above mentioned article [1] the notion of a time-dependent Gibbs free energy has been introduced to explain the observed time-pattern of embryo growth in seeds. Furthermore, the notion of a non-random thermal communication has been inferred from an inspection of the shapes of germination time distributions. It can be shown, however, that the reasoning leading to the time-dependent thermodynamic potential is based on inappropriate interpretation of kinetic equations, and that the shape of the distributions of germination time might be a natural consequence of the initial distribution of embryo size in the seeds.Discussion about the Paper Seed Germination as a Thermobiological Problem by L. G. Labouriau Radiation and Environmental Biophysics 15:345–366 (1978)     

Target antigens in malaria transmission blocking immunity

Malaria transmission blocking immunity has been found to operate against two distinct phases of development of malaria parasites in the mosquito midgut: (i) against the extracellular gametes and newly fertilized zygotes shortly after ingestion by a mosquito of parasitized blood and (ii) against the zygotes during their subsequent development into ookinetes. Immunity is antibody-mediated and stage-specific. A set of three proteins, synthesized in the gametocytes, expressed on the surface of the gametes and newly fertilized zygotes and subsequently shed during later transformation of the zygotes, has been identified as the target antigens of anti-gamete fertilization blocking antibodies. A single protein, synthesized and expressed on the zygote surface during its development to ookinetes, has been identified as the target of antibodies which block the development of the fertilized parasites in the mosquito. Immunization of human populations against gamete or zygote antigens, while not directly protecting an immunized individual from inflection, would reduce the transfer of malaria within the population. Such immunity, in addition to reducing the overall rate of malaria transmission, would, if combined with a vaccine against the asexual (disease-causing) stages, reduce the chance of selection of parasites that are resistant to the asexual vaccine by preventing their entry into the mosquito population.     

Reproductive strategies of coastal marine fishes in the tropics

Synopsis A synthesis of ethnobiological, behavioral and physical oceanographic information leads to the conclusion that temperate zone models of reproductive strategy are inapplicable to many fishes of the coastal tropics. Intense predation appears to exert heavy selection pressure on fishes that spend their adult lives in coral, mangrove or tropical seagrass communities. Many exhibit spawning behaviors and spawn at times and locations that favor the transport of their pelagic eggs and pelagic larvae offshore where predation is reduced. This creates a countervailing selection pressure — the need to return the larvae to shallow water once they are ready to colonize their post-larval habitats. Accordingly, spawning is often concentrated at times of the year when prevailing winds or currents are at their weakest, thereby reducing the transport of larvae long distances from where they originated. Spawning is also concentrated in the vicinity of nearshore gyres which similarly favor the ultimate return of the larvae to their natal area. Among these species, therefore, offshore larval dispersal does not seem to be an adaptation for dispersal of the species, but rather an evolutionary response to intense predation pressure in the adult habitats. Lunar reproductive periodicity is more common among these species than has previously been recognized, and is one of the strategies employed to enhance the offshore flushing of eggs and larvae.This paper forms part of the proceedings of a mini-symposium convened at Cornell University, Ithaca, N. Y. 18–19 May 1976, entitled Patterns of Community Structure in Fishes (G. S. Helfman, ed.).Contribution No. 524, Hawaii Institute of Marine Biology, University of Hawaii, Honolulu.     

Distribution of testosterone-estradiol binding globulin (TeBG) in the higher vertebrates

The presence of testosterone-estradiol binding globulin (TeBG) in a variety of higher vertebrate species has been investigated by an ammonium sulphate precipitation technique. TeBG has been demonstrated in significant amounts in primates, carnivora, marsupiala, and some artiodactyla, even in circumstances where previously electrophoretic studies failed to identify it. For the first time it has also been shown in trace amounts in certain rodents and birds. TeBG in the kangaroo substantiates the primitiveness of the protein in the mammal line and its absence in certain orders and species of eutherian mammals must represent a secondary loss.     

Characterization of the collagen synthesized by cultured human smooth muscle cells from fetal and adult aorta.

Smooth muscle cells were grown from explants of the tunica media of fetal and adult human aorta. Collagen was isolated after incubation with [14C]glycine and was characterized by ion-exchange chromatography. All cells investigated synthesized two types of collagen: Type I (chain composition [alpha1(I)]2alpha2) and type III (chain composition [alpha1(III)]3). The collagen made by cells from adult donors contained approximately 70% type I and 30% type III collagen. This corresponds to the collagen composition in teh original tissue. No age-relate change in the type I/type III ratio was found with cells from donors between 9 and 67 years of age. On the other hand, the type III portion of the collagen made by fetal cells was markedly less (about 15-20% of total collagen).     

Ribosomal protein S20 purified under mild conditions almost completely inhibits its own translation

Summary The efficiency of ribosomal protein S20 to act as repressor of its own synthesis in an in vitro system was found to depend greatly on the procedures employed to purify this protein. Whilst conventionally purified r-protein S20 inhibited its own synthesis by some 30%, up to 90% inhibition was observed if milder purification conditions were used. Evidence is presented that the latter preparation shows also a higher binding affinity to 16S rRNA.