The races of maize: III. choices of appropriate characters for racial classification

Analyses of variance for 111 characters from 55 races and subraces of maize from eastern South America grown at Piracicaba, S. P., Brazil, between 1960 and 1965, indicated that those characters which were least affected by environmental factors and interactions were reproductive characters. In particular, the component of variance due to differences among races for certain ear and kernel characters was greater than the sum of the corresponding components due to differences among years and race by year interactions. The converse was true for all vegetative characters. Tassel characters tended to be intermediate between ear and plant characters. While some indices had larger components of variance attributable to racial differences than to the effects of environment and/or environmental interaction, some commonly used ones, such as cob/rachis and rachilla/kernel indices, proved to be quite susceptible to environmental influences. Again, indices based upon solely vegetative characters were consistently influenced more strongly by environmental factors and interaction than were those based on reproductive characters.     

中国山杨与美洲山杨杂交育种的研究

通过采用山杨7个种源11株优树与美洲山杨8个优树进行杂交,共进行88个组合,其中46个杂交获得成功,进行播种育苗,建立子代测定林。5年的试验结果表明,山杨作母本时,以苇河种源较好;美洲山杨作父本时T-32-57和T-28-56较好,其它亲本的杂交组合尚需进一步观察。而在部分山杨与美洲山杨杂交种无性系试验林中,Id42-3、Gd42-1、Ca42-1和Bd44-1生长速度快、光合能力较强,抗病虫能力强,是有希望的杂交种。     

Genetic differences between the Chinese and the European races of the common carp III. Gonad abnormalities in hybrids

Abnormalities in the gonads of carp, Cyprinus carpio L., were present in a relatively high proportion of hybrids derived from the Chinese and European strains. The aberrations involved were the absence or marked reduction of the gonads in mature fish.     

New observations on the skull of Archaeopteryx

Although skeletal remains of the iconic oldest known avialian Archaeopteryx have been known for almost 150 years, several aspects of the cranial anatomy of this taxon have remained enigmatic, mainly because of the strongly flattened and often fractured and incomplete nature of available skull materials. New investigation of the skulls of the recently described, excellently preserved tenth (Thermopolis) and the seventh (Munich) specimens revealed several previously unrecognized characters and helps to resolve some problematic issues. Thus, the nasal of Archaeopteryx shows a lateral notch for the lacrimal, as is found in many other saurischian dinosaurs, the maxilla clearly participates in the margin of the external nares, and there seems to be a pneumatic foramen in the lacrimal, comparable to the lacrimal fenestra found in many non-avian theropods. In the braincase, Archaeopteryx shows pneumatic features reminiscent of non-avian theropods, including a ventral basisphenoid recess and an anterior tympanic recess that is laterally incised into the basisphenoid/prootic. Most importantly, however, the postorbital process of the jugal shows a facet for the suture with the postorbital, thus resolving the question of whether Archaeopteryx had a closed postorbital bar. A new reconstruction of the skull of Archaeopteryx is presented, making the skull of this taxon even more theropod-like than previously recognized. Furthermore, the closed postorbital bar and the configuration of the bones of the skull roof cast serious doubt on claims that an avian-style cranial kinesis was present in this taxon.     

New observations on the bioluminescence of echinoderms

Bioluminescence has been observed in two species of Ophiuroidea, six species of Asteroidea, nine species of Holothuroidea and two species of Crinoidea. The luminescent responses are described and the intensities and time courses of the responses of some species are given.
Histological investigations have indicated possible luminous cells in the Holothuroidea, but the results in other classes remain equivocal. Preliminary analyses of the chemistry of bioluminescence indicate that a similar system may be responsible for bioluminescence in all four classes, although the visible manifestations of the system vary considerably.     

Somatic nuclear division in the sporidia of Ustilago violacea. III. Ultrastructural observations.

The paper provides detailed ultrastructural observations on nuclear division in the smut fungus Ustilago violacea and is based on previous light-microscopic work outlining the division in living and stained cells. The division as in many other Basidiomycetes is not intranuclear, but occurs within a partially disrupted membrane. The division takes place after migration of most of the nucleus into the bud cell, after limited breakdown of the nuclear membrane, and after the formation of a spindle between two spindle-pole bodies (SPB). The remaining part of the nucleus containing the nucleolus is left behind in the parent cell and degenerates there. The SPB, as in other Basidiomycetes, is a dome-shaped relatively structureless body, quite distinct from the flat plaques of many Ascomycetes and the elaborat centrioles of Phycomycetes. The SPB divides shortly before migration into the daughter cell and invariably is located at the apex of the migrating nucleus. Nuclear division is completed when the two masses of chromatin clustered about each of the SPB's are separated as the spindle elongates. One daughter neculeus reforms in the bud and the other is reformed in the mother cell. Cells fixed and stained by conventional light-microscopic methods were examined in the light of the electron-microscopic observations to determine whether these procedures induce artefacts. Aceto-orcein and Giemsa when used cold were found to produce relatively artefact-free preparations. However, previous results in which the cells were warmed gently in these stains are now seen to contain artefacts in the form of contracted chromatinic granules often arranged in chains. These artefacts may provide useful information but clearly they must be interpreted cautiously until the nature of the changes induced by heating are known.     

Field observations on nitrogen catch crops. III. Transfer of nitrogen to the succeeding main crop

In temperate climates with a precipitation surplus during autumn and winter, nitrogen (N) catch crops can help to reduce nitrogen losses from cropping systems by absorbing nitrogen from the soil and transfer it to a following main crop. In two field experiments the catch crop species winter rye (Secale cereale) and forage rape (Brassica napus ssp. oleifera (Metzg.) Sinsk) or oil radish (Raphanus sativus spp. oleiferus (DC.) Metzg.) were planted end of August and 3 weeks later with a non-limiting supply of N and zero-N controls. In the next spring catch crops were incorporated into the soil. In Expt 1, N transfer was measured as (i) the N uptake of a potato test crop, grown with zero and 12.5 g m^–2 N applied, and (ii) the increase in soil mineral N (0–30 cm) in uncropped soil covered with polythene film. In Expt 2, N transfer was measured as the increase in soil mineral N in covered cylinders placed in uncropped soil (in situ incubation). Subsidiary laboratory incubations were performed in Expt 2. In Expt 1, the apparent recovery in potato of fertilizer N (R _f) was 0.56. The recovery in potato of N mineralized from 'native' N pools other than catch crop material (R _n) ranged from 0.43 to 0.51, depending on the value assumed for the depth of N extraction by potato roots. The average recovery in potato of incorporated catch crop N (R _c) was 0.34. Expressed as `fertilizer N replacement factor' (F _r) the latter was 0.61 (i.e. 1 kg of N in catch crop material counts for 0.61 kg fertilizer N). Under the film in Expt 1 the fraction net mineralization of incorporated catch crop N (M _n) was 0.36 on August 11 and 0.43 on October 18. In Expt 2, the average value of M _n was 0.31, which was lower than in Expt 1 and probably associated with the drier soil in Expt 2. In the laboratory incubations (20°C) M _n showed values up to 0.54 after 84 days with the largest rates of change in mineralization occuring early after the start of the incubation. In conjunction with literature data it is concluded that cultivation of nitrogen catch crops shows promise as a means to reduce N input and N losses in temperate climates with wet winters.     

Development of the nasal septum in rabbits. III. Quantitative observations on cells and intercellular substance

With the aim to further characterize the various regions of the nasal septum, the following measurements were made: In the thin anterior region and in the thick regions in the middle and posterior parts of the septum the quantitative relationships between cells and intercellular substance as well as the size of the cells were determined. The material used, included transverse and horizontal sections through the nasal septum of rabbits of ages of 1 day and 2, 4, 6, 8, 12 and 24 weeks. The results showed that in the thin anterior region the relationship between cells and intercellular substance remains constant, while in the two thick regions the amount of intercellular substance proportionately increases. In the thick regions, the cells are always larger than in the thin region. The rapid growth of the cells between the 4th and the 6th week coincides with a growth-spurt of the whole head.     

New observations on the compact myelin proteome

Myelin formation and maintenance depends on the establishment of two structurally and biochemically discernible domains: (a)compact myelin, that is multilamellar stacks of plasma membrane sheets; and (b) cytoplasmic channels that border the compact myelin domains, attach them to the cell body and anchor the myelin sheath to the axonal membrane. To identify proteins involved in the organization of these domains we took advantage of the high lipid content of compact myelin to separate it cleanly from other neural membranes and then used reverse-phase HPLC coupled to Electro-Spray Double Mass Spectrometry('MudPIT') to characterize the proteome of this sample. MudPIT allowed us to sidestep the bias of 2D-PAGE against either highly charged or transmembrane proteins. Thus, of 97 proteins that presented at least two, fully tryptic peptides (a stringent threshold), seven were well known myelin markers, including the mayor CNS myelin proteins: proteolipid protein and myelin basic protein, which are not resolvable by 2D-PAGE. Furthermore, we have confirmed and extended the known compact myelin proteome by 22 proteins and confirmed that CNS and PNS myelinated tracts present Sirtuin 2, a tubulin deacetylase, and Septin7, a small GTPase that is likely to be involved in membrane and cytoplasm partitioning.     

Studies on the testis of the camel (Camelus dromedarius). III. Histochemical observations

Synopsis The histochemical localization of carbohydrates and lipids and some oxidative, hydrolytic and steroid-linked enzymes has been studied in the testis of the camel with particular reference to the effect of the season on the distribution of these substances. PAS-positive, but diastase-resistant, material was seen mainly in the wall of blood vessels and in the boundary tissues of the seminiferous tubuli recti and rete testis. Clear cyclical changes were seen for glycogen in the lining epithelium of the seminiferous tubules. Glycogen was most abundant in early stages and very scanty or absent in the late stages of the cycle of the seminiferous epithelium. Numerous small lipid droplets were seen in the interstitial cells and towards the lumen of the seminiferous tubules that contain elongate spermatids or spermatozoa. Large lipid droplets were also demonstrable in the basal layer of the seminiferous epithelium and in the cytoplasmic debri. Alkaline phosphatase was demonstrated in the boundary tissues of the seminiferous tubules, tubuli recti and reti testis and in the cells bordering the lumen of the seminiferous tubules. Succinate and lactic dehydrogenases showed similar patterns of distribution in the interstitial elements and intratubularly.⁵-3 hydroxysteroid dehydrogenase was exclusively demonstrated in the interstitial cells. 17-hydroxysteroid dehydrogenase could not be demonstrated. The season seems to have no effect on the distribution of all these substances. The possible significance of all these findings is discussed.