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V Pesce Delfino A De Lucia V Scattarella T Lettini R Lenoci V Mitolo 《Bollettino della Società italiana di biologia sperimentale》1984,60(7):1301-1307
An analytical morphometrical investigation of fronto facial profile of Plesianthropus transvaalensis was carried out by means of Fourier spectral series. Amplitude of contributors was evaluated in comparison with harmonic sets of a modern skull and two "mosaics" obtained by a convenient merging of segments of modern and hominid skull profiles. Patterns are distinctly different in Plesianthropus and modern profile because amplitude of second harmonic is greater than first in the former and viceversa in the latter; moreover while in Plesianthropus first and second harmonic give the same phase, it does not occur for modern skull. Fourier series of "mosaic" obtained by frontal profile of Plesianthropus and facial profile of modern resembles the set of modern skull while "mosaic" of modern frontal profile and hominid facial one resembles closely pattern of Plesianthropus. 相似文献
33.
The sporophyte foot of the mossTimmiella barbuloides consists of an unistratose epidermis of transfer cells, a parenchymatous cortex, and a small central strand consisting only of hydroids. The parenchymatous tissue of the vaginula develops one layer of transfer cells opposite the foot, whose lower extremity extends into the gametophyte stem's central strand. From the bottom to the top of the foot the ultrastructure of the sporophyte transfer cells shows some gradual changes that appear related to a functional specialization of these cells. According to a centripetal gradient, the quantity of plastid starch progressively lessens in both vaginula parenchyma and foot cortex. the observed morphological patterns suggest that in the foot-vaginula complex nutrients are translocated radially up to the sporophyte central strand. 相似文献
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Francesca Clementi Jone Rossi Lucia Costamagna Jolanda Rosi 《Antonie van Leeuwenhoek》1980,46(4):399-405
Schwanniomyces castellii and Endomycopsis fibuligera Produced extracellular amylase(s) when grown on various carbon sources and at different pH values. Both yeast species showed significant amylase synthesis in the presence of either maltose or soluble starch. On the other substrates tested (glucose, cellobiose, sucrose, trehalose, melezitose, raffinose, ethanol, glycerol) differences were found regarding growth and amylase production. Free glucose in the culture medium apparently inhibited enzyme synthesis. The pH range allowing maximal growth and amylase production was 4.5–6.0 for E. fibuligera and 5.5–7.0 for S. castellii. 相似文献
35.
3H-thymidine incorporation and DNA-polymerase activity during early hours of wheat embryo germination at two viability levels
have been studied. The patterns of two biosynthetic activities, as well as the dependence of DNA synthesis on protein synthesis,
indicated the presence of a delay in the early phase of imbibition of the aged embryos with respect to viable germs. 相似文献
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Vittoria Nuti Ronchi Lucia Giorgetti Mariagrazia Tonelli Guido Martini 《Plant Cell, Tissue and Organ Culture》1992,30(2):107-114
Cytological analysis of different carrot cell lines in culture has shown various cytogenetic anomalies generating new levels of ploidy and novel chromosome numbers. Polyploidy may be considered a reservoir of variability that can be released in the form of distinct new segregants of different ploidy. Mechanisms alternative to mitosis (reductional grouping, prophase chromosome reduction) operate from a polyploid state (possibly reached by means of endopolyploidy, endomitosis, nuclear fusion, or restitution nuclei) to generate new levels of ploidy and novel chromosome numbers necessary for selection to operate in vitro. The segregational phenomena require chromosome recognition in haploid set complements and abnormal behaviour of mitoses; the resulting chromosome variability suggests that chromosomes are arranged, in the resting nuclei, in an orderly and predictable manner.The knowledge of the molecular events governing these mechanisms, and how to control them, would be of great help for future applications of plant cell culture. 相似文献
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Scatter hoarding by kangaroo rats (Dipodomys merriami) and pilferage from their caches 总被引:9,自引:0,他引:9
Daly Martin; Jacobs Lucia F.; Wilson Margo I.; Behrends Philip R. 《Behavioral ecology》1992,3(2):102-111
We observed radio-implanted Merriam's kangaroo rats disposingof 10-g bonanzas of rolled oats in 48 trials in the field. Theprincipal determinant of the initial disposition of discoveredfood was apparently its distance from the day burrow: food foundwithin about 10m was mainly larder hoarded, whereas food encounteredfarther afield was usually dispersed immediately in shallowcaches. Cache sites were newly dug for the purpose and not reused;most caches were nearer the current day burrow than was thefood source, but a few were placed far from both the cacher'sday burrow and its habitual nocturnal range. An experiment withartificial caches indicated that security from discovery increaseswith spacing and with proximity to perennial shrubs. Nine kangaroorats cached dyed food, and fecal dye traces revealed extensivepilferage from five of them, by both conspecifics and otherrodent species. Limited evidence indicates that food encounterednearer home and initially larder hoarded was more secure frompilferage than food initially scattered, and yet kangaroo ratswere observed to scatter caches soon after initial larder hoarding.A kangaroo rat whose dyed stores escaped pilferage fed fromthem at intervals for at least 12 days. Even cachers who incurredpilferage made as much, or more, use of their caches as anythief, suggesting that scattering caches may be a defense againstcatastrophic losses. 相似文献