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321.
The von Bertalanffy growth model was applied to franciscana dolphins ( Pontoporia blainvillei ) incidentally caught in fishing nets on the São Paulo/Paraná coasts (25°00'–25°58'S), and compared with the growth of franciscanas incidentally caught on the Rio Grande do Sul coast (29°–33°S). In both locations, a difference was noted between the growth of males and females, confirming the sexual dimorphism of the body proportions of this dolphin. The growth curves of the dolphins from São Paulo/Paraná were significantly different ( P < 0.01) from those obtained from Rio Grande do Sul, with significantly smaller animals in the former area. On the São Paulo/Paraná coast, the stabilization of the growth curves happened at a total length of 113 and 129 cm for males ( n = 23) and females ( n = 18), respectively. In Rio Grande do Sul, they stabilized at 130 cm for the males ( n = 59) and at 146 cm ( n = 48) for the females. These results corroborate the morphometric differences previously mentioned in the literature, which resulted in the identification of a smaller northern form and a larger southern form of P. blainvillei . The data here presented can be used for future comparisons of changes in growth parameters of these two franciscana stocks and help to develop proper conservation programs for the species. 相似文献
322.
D. J. Wolyn D. A. St. Clair J. DuBois J. C. Rosas R. H. Burris F. A. Bliss 《Plant and Soil》1991,138(2):303-311
The improvement of N2 fixation in legumes may lead to increased yields and reduced fertilizer requirement. Levels of N2 fixation were determined for three cultivars and nine progeny lines from two inbred backcross common bean (Phaseolus vulgaris L.) populations that were grown at Hancock, Wissconsin in 1984 and 1985 using 15N-depleted (NH4)2SO4. The high N2-fixing line Puebla 152 was the donor parent for both inbred backcross populations and the cultivars Porrillo Sintetico and Sanilac were the recurrent parents for populations 21 and 24, respectively. Total N yield, fixed N2 and % N derived from the atmosphere were determined for whole plants and plant parts at the R3 (50% bloom) and R9 (maturity) growth stages. Significant year-by-line interactions were found for N2 fixation traits among the population 21 lines and parents, but not for population 24 lines and their parents. Measures of N2 fixation at R3 were inadequate to predict N2 fixation at R9. Population 24 lines and parents differed for N2 fixation ability at R9, and fixed N2 was correlated with maturity. The recovery of an inbred backcross progeny line, 24-21, which matured earlier and fixed more N2 than the recurrent parent Sanilac indicated that N2 fixation was heritable and that favorable alleles, independent of maturity, were recovered from a late-maturing, high N2-fixing donor parent by utilizing the inbred backcross breeding method. Since most fixed N2 and non-fixed N (>80%) was found in the seeds at maturity, and most lines did not vary for the distribution of nitrogen throughout the plant, selection for improved remobilization of nitrogen to the seed to increase yield is impractical in this genetic material. The highest N2-fixing lines tended to have high and similar % Ndfa in all plant parts. 相似文献
323.
C. Calderón J. Lacey A. McCartney I. Rosas 《International journal of biometeorology》1997,40(2):71-80
The effect of an urban climate upon the spatial and temporal distribution of Deuteromycete spores was studied during 1991
using Burkard volumetric spore traps in two areas of Mexico City with different degrees of urbanization. Deuteromycete conidia
formed the largest component of the total airborne fungal spore load in the atmosphere of Mexico City, contributing 52% of
the spores trapped in an urban-residential area (southern area) and 65% of those in an urban-commercial area (central area).
Among the most common spore types, Cladosporium and Alternaria showed a marked seasonal periodicity with significant differences in concentration (P<0.05) between the dry and wet seasons. Maximum conidial concentrations were found during the end of the wet season and the
beginning of the cool, dry season (October–December). Daily mean concentrations of the predominant airborne spore types did
not differ significantly between the southern and central areas. Daily mean spore concentrations were significantly correlated
(P<0.05) in southern and central areas with maximum temperature (south, r = –0.35; central, r = –0.40) and relative humidity (south, r = 0.43; central, r = 0.29) from the previous day. Moreover, multiple regression analysis of spore concentrations with several meteorological
factors showed significant interactions between fungal spores, relative humidity and maximum temperature in both areas. The
diurnal periodicity of Cladosporium conidia characteristically showed two or three peaks in concentration during the day at 0200–0400, ∼ 1400 and 2000–2200 hours,
while that of Alternaria showed only one peak (1200 to 2000 hours) in both areas. Maximum concentrations of these spores generally occurred 2–4 h earlier
in the southern than in the central area. The lag in reaching maximum concentrations in the central area probably resulted
from differences in the local conditions between the study areas, and from spores transported aerially into the city from
distant sources. The analysis of maximum hourly concentrations of Cladosporium and Alternaria spores during 1 month of the dry season (February), and another month of the wet season (September) showed significant differences
between the two study areas. Environmental factors and sources (green areas) affected diurnal changes in conidial concentration
in the southern area (urbanization index, UI, 0.25), but not in the central area (UI 0.97). In general, spore concentrations
were greatest in the southern area when relative humidities were low, and temperatures and wind velocities were high. It was
difficult to establish effects of climatic factors on the spore concentration in the city centre. This probably results from
the large amounts of air pollution, the heat island phenomenon, and from the distant origin of trapped conidia obviating aerial
transport. Nevertheless, the seasonal and diurnal distributions of conidia found were similar to those reported for other
tropical regions of the world.
Received: 13 August 1996 / Accepted: 4 December 1996 相似文献
324.
L E Rodriguez M Ocampo R Vera A Puentes R Lopez J Garcia H Curtidor J Valbuena J Suarez J Rosas Z Rivera M Urquiza M E Patarroyo 《The journal of peptide research》2003,62(4):175-184
The erythrocyte-binding antigen 140 (EBA140) sequence was chemically synthesized in 61 20-mer sequential peptides covering the entire 3D7 protein strain, each of which was tested in erythrocyte-binding assays. Peptides 26135, 26144, 26147, 26160, 26170 and 26177 presented high erythrocyte-binding activity, with affinity constants ranging from 350 to 750 nM. Critical erythrocyte-binding residues were determined by competition-binding assays with glycine analogous peptides. Cross-linking assays with SDS-PAGE from high erythrocyte membrane protein binding peptides showed that all these peptides bound specifically to 25, 52 and 75 kDa erythrocyte membrane proteins. The nature of these receptor sites was studied in peptide-binding assays using enzyme-treated erythrocytes, showing that these protein receptors are susceptible to structural changes provoked by enzyme treatment (neuraminidase, trypsin or chymotrypsin). Inhibition invasion assays in 'in vitro' cultures showed that all specific high binding sequences were able to inhibit invasion by 11-69% at 200 microM concentration. 相似文献
325.
E. Aguirre J. L. Arsuaga J. M. Bermúdez de Castro E. Carbonell M. Ceballos C. Díez J. Enamorado Y. Fernández-Jalvo E. Gil A. Gracia A. Martín-Nájera I. Martínez J. Morales A. I. Ortega A. Rosas A. Sánchez B. Sánchez C. Sesé E. Soto T. J. Torres 《Human Evolution》1990,5(1):55-73
The Atapuerca railway Trench and Ibeas sites near Burgos, Spain, are cave fillings that include a series of deposits ranging
from below the Matuyama/Bruhnes reversal up to the end of Middle Pleistocene. The lowest fossil-bearing bed in the Trench
contains an assemblage of large and small Mammals includingMimomys savini, Pitymys gregaloides, Pliomys episcopalis, Crocuta crocuta, Dama sp. and Megacerini; the uppermost assemblage includesCanis lupus, Lynx spelaea, Panthera (Leo) fossilis, Felis sylvestris, Equus caballus steinbeimensis, E.c. germanicus, Pitymys
subterraneus, Microtus arvalis agrestis, Pliomys lenki, and alsoPanthera toscana, Dicerorbinus hemitoechus, Bison schoetensacki, which are equally present in the lowest level. The biostratigraphic correlation and dates of the sites are briefly discussed,
as are the paleoclimatic interpretation of the Trench sequences. Stone artifacts are found in several layers; the earliest
occurrences correspond to the upper beds containingMimomys savini. A set of preserved human occupation floors has been excavated in the top fossil-bearing beds. The stone-tool assemblages
of the upper levels are of upper-medial Acheulean to Charentian tradition. The rich bone breccia SH, in the Cueva Mayor-Cueva
del Silo, Ibeas de Juarros, is a derived deposit, due to a mud flow that dispersed and carried the skeletons of many carnivores
and humans. The taxa represented are:Ursus deningeri (largely dominant),Panthera (Leo) fossilis, Vulpes vulpes, Homo sapiens var. Several traits of both mandibular and cranial remains are summarized. Preliminary attempts at dating suggest that the
Ibeas fossil man is older than the Last Interglacial, or oxygen-isotope stage 5. 相似文献
326.
327.
Morphological changes in sperm are one aspect of a maturation process during epididymal transit in marnrnals. The literature mentions only, for different strains of rats, a remodeling and decrease in size of the acrosome. In the present work, the sperm were obtained from caput, corpus, and cauda epididymis of the albino rat. Samples were processed for scanning electron microscopy, with routine techniques, and for light microscopy and video microscopy. It appeared, with these techniques, that the acrosomal curvature and the whole head surface area of the rat sperm decrease during the epididymal transit. To measure these changes, a geometrical method was designed, and surface measurements were made using a computer program. It was found that the caput sperm head has the greatest surface area and a sharper acrosome bend than the cauda sperm. In an attempt to explain the above-mentioned changes, the suggestion is offered that some compactation of the nucleus and acrosomal material could be related to the decrease of the surface area. 相似文献
328.
329.
M. A. Munguía‐Rosas V. J. Sosa M. E. Jácome‐Flores 《Plant biology (Stuttgart, Germany)》2010,12(4):578-586
It has been suggested that there is a geographic dichotomy in the pollination systems of chiropterophilous columnar cacti: in intra‐tropical areas they are pollinated almost exclusively by bats, whereas in extratropical areas they are pollinated by bats, birds and bees. However, currently the studies are clumped both taxonomically (mainly Pachycereeae species) and geographically (mainly in the Tehuacan Valley and the Sonoran Desert). This clumping limits the possibility of generalising the pattern to other regions or cactus tribes. Only four of the 36 chiropterophilous cacti in Pilosocereus have been studied. Despite the tropical distribution of two Pilosocereus species, bees account for 40–100% of their fruit set. We examined how specialised is the pollination system of P. leucocephalus in eastern Mexico. As we studied tropical populations, we expected a bat‐specialised pollination system. However, previous studies of Pilosocereus suggest that a generalised pollination system is also possible. We found that this cactus is mainly bat‐pollinated (bats account for 33–65% of fruit set); although to a lesser degree, diurnal visitors also caused some fruit set (7–15%). Diurnal visitors were more effective in populations containing honeybee hives. P. leucocephalus is partially self‐compatible (14–18% of fructification) but unable to set fruit without visitors. Despite the variation in pollination system, P. leucocephalus shows more affinity with other columnar cacti from tropical regions than with those from extratropical regions. Although we report here that a new species of tropical Pilosocereus is relatively bat‐specialised, this Cereeae genus is more flexible in its pollination system than the Pachycereeae genera. 相似文献
330.
Rosas IO Richards TJ Konishi K Zhang Y Gibson K Lokshin AE Lindell KO Cisneros J Macdonald SD Pardo A Sciurba F Dauber J Selman M Gochuico BR Kaminski N 《PLoS medicine》2008,5(4):e93