Plant communities of the Stirling Range,Western Australia

The Stirling Range is a mountain system of Proterozoic origin in the southern part of Western Australia, reaching an altitude of 1000 m; it consists of acid rocks and has a mediterranean climate with a rainfall of 500 - 550 mm/yr. It is the only extensive mountain system of this portion of the continent and presents a rich endemic flora. The vegetation of the area was investigated from 1984 to 1992; 68 phytosoci-ological releves, ecological observations and extensive floris-tic collections were made. On the basis of multivariate analysis eight communities have been distinguished: Eucalyptus woodland, mallee, evergreen shrubland (plain, mountain and slope), and herbaceous communities of wet sands, springs and rocks. The Stirling Range is the only area in the south of Western Australia where vegetation belts can be recognised.     

陕西省钩土蜂二新种（膜翅目：钩土蜂科）

在西北农业大学昆虫博物馆收藏的钩土蜂科(Tiphiidae)标本中,发现有二新种记述于此,一种以周尧教授的姓氏来命名,以感谢他对我们此项研究的支持,模式标本保存在北京农业大学昆虫标本室。1.网纹钩土蜂Tiphia retincisura,新种(图1A—D) 雌 体长9.5mm,肩片、足皆黑色。后足基跗节内侧有纵沟。并胸腹节背面两侧呈针刮状;第一腹节背板刻点端前带中部1～2列,两侧加宽、刻点排列不规则。额上、前胸背板和中胸侧板等处有网状印纹。     

Retention deficit for avoidance training in hypophysectomized rats: Time-dependent enhancement of retention performance with post-training ACTH injections

These experiments examined the effects of hypophysectomy on retention of avoidance training. In addition, the experiments examined the effects, on retention, of post-training ACTH injections administered to hypophysectomized rats. Rats were trained in a visual discriminated avoidance Y maze. Each rat received six training trials followed by six retraining trials the next day. Retention was measured by the number of correct choices during the retraining trials. When trained with a low-footshock intensity (0.8 mA), hypophysectomized rats showed retention performance which was significantly poorer than that of intact animals. There was no significant difference in performance when the animals were trained with a higher footshock intensity (1.4 mA), in part because of poorer retention performance of intact animals under these training conditions. Under both footshock conditions, a single post-training injection of ACTH enhanced later retention performance of hypophysectomized rats. This effect on memory was timedependent; injections delayed 2 or 6 hr after training did not significantly enhance retention. These findings are consistent with the view that hormonal responses to training may modulate later retention of the training experience.     

Comparison of the acid denaturation of several hemoglobins which differ in amino acid sequence

There are pronounced differences in kinetic and thermodynamic stability between human and horse hemoglobins. Since the amino acid sequences of the α, β dimers of horse and human hemoglobins differ in 61 locations, it is difficult to account for them in terms of specific direct or indirect effects of the sequence differences. Rhesus hemoglobin differs from human in only 12 locations and its stability resembles that of human more closely than does horse, although pronounced differences remain. The stabilities of rhesus ferrihemoglobin and deoxyhemoglobin (Hb⁺ and Hb °) are intermediate between those of the corresponding high-spin forms of horse and human hemoglobin; but there are only small or negligible differences between the low-spin forms (carbonylhemoglobin and oxyhemoglobin) of the two species. The equilibrium isotherm between native and acid unfolded forms of rhesus Hb⁺ resembles that of horse more than that of human, but it is slightly more stable and slightly less cooperative. The effects of octanol on the rates of unfolding of rhesus ferrihemoglobin are only slightly smaller than with human. There is no effect of octanol on the unfolding rate of any of the CO hemoglobins. Unlike the equilibria of horse and human, octanol is also without effect on the unfolding equilibrium of rhesus ferrihemoglobin, and thus qualifies as a true catalyst of the initial stage of the acid unfolding reaction of the monkey ferriprotein. Differences in stability are tentatively attributed to a limited number of the 12 differences between the two proteins.     

Numerical method for equilibrium fluorescence polarization

A computer program for making first approximations of equation constants, and for fitting the equilibrium fluorescence polarization equation to data by successively improving the constant values is described. The techniques used in making the first approximations represent a substantial improvement over methods previously available.     

Developmental uncoupling between blastoderm and yolk cell in the embryo of the teleost Fundulus

During cleavage and blastula stages of embryos of the teleost Fundulus heteroclitus all of the cells are both electotonically coupled and dye coupled to one another, as determined by microelectrode impalements and spread of Lucifer Yellow. At about the time that gastrulation begins we observed a specific loss of junctional coupling between the yolk cell and cells of the blastoderm. Passage of Lucifer Yellow between the yolk cell and blastoderm was reduced at stage 12 (late blastula), and not detected at stage 13 and thereafter, although cells of the blastoderm remain dye coupled to one another through gastrula stages. Also, junctional electrical coupling between the yolk cell and blastoderm became substantially reduced at stage 13 and thereafter. The loss of coupling at this specific cell apposition and time and the large size of the yolk cell may prove useful in analyzing the underlying cellular mechanisms.     

Tissue healing and septate desmosome formation in hydra

Tissue healing was studied in hydra tissue grafts by means of light and electron microscopy. Healing is begun by the gastrodermis: subsequently the epidermis fuses and the mesoglea is repaired. Epidermis fusion is first brought about by long processes from the basal portions of the epithelial cells bridging the wound gap and adhering to opposing cells. Irregular septate desmosomes form early in this process and continuously become more neatly organized. Concommitant with the healing process at the graft site, neighboring cells are also rearranging, their septate desmosomes undergoing transient disorganizations. We conclude that the organization of septate junctions is dynamic, and may be undergoing a balanced but continuous, steady state turnover. During the healing process the forces acting on the desmosomes, and other aspects of the cells' architecture, are not balanced, and the junctions grow and become more highly organized.     

云南省(虫齿)目二新种和灰背蛇(虫齿)的记述((虫齿)目:厚(虫齿)科、叉(虫齿)科、围(虫齿)科)

本文记述了云南省(虫齿)目二新种,Tapinella bannana sp.n.和Peripsocus plurimaculatus sp.n.及一新种记录种Ophiodopelma semicets Lee and Thornton,其雄虫为首次记载。     

Lever pressing for pups: Evidence for hormonal influence upon maternal behavior of mice

Five experiments were performed to determine the extent to which hormones influence maternal behavior of the female mouse. The number of pup-reinforced lever presses served as the measure of maternal behavior. In Experiment 1 it was found that postpartum mice performed significantly more pup-reinforced lever presses than intact or ovariectomized virgins. The second experiment showed that the augmentation of responding was unique to the postpartum period since responding was not facilitated during the last three days of pregnancy. Experiment 3 established that the postpartum augmentation of responding was mediated by the termination of pregnancy and not by parturition per se. It also was observed that the earlier during gestation pregnancy was terminated the greater the decline in response rate. Experiment 4 proved that ovarian secretions play a critical role in the pregnancy-terminated facilitation of pup-reinforced lever pressing. The final experiment demonstrated that the termination-of-pregnancy effect on responding in all likelihood is mediated by the synergistic actions of estrogen stimulation and progesterone withdrawal. The results show that the maternal behavior of the mouse, like that of the rat, is responsive to hormonal stimulation.     

Differential replication of ribosomal gene repeats in polytene nuclei of Drosophila.

The genes coding for the 18S and 28S rRNAs in D. melanogaster were examined using Southern transfers of DNA from diploid or polytene tissue. A ribosomal gene repeat 12 kb in length is present in DNA from diploid tissue of males and is the major repeat on the Y chromosome. This repeat is present in low amounts on the X chromosome, which contains major repeats of 17 and 11.5 kb. In polytene nuclei of males, the 12 kb band is disproportionately replicated, and only a very low amount of the 11.5 kb repeat and no 17 kb repeat are detected. Polytene nuclei of females contain reduced amounts of the 17 kb repeat relative to the 11.5 kb repeat. This disproportionate replication of specific ribosomal gene repeats suggests that polytenization of the rDNA may involve an extrachromosomal mechanism. Evidence that genes from only one nucleolus organizer are replicated during polytenization in X/Y and X/X flies is discussed. A method for analyzing DNA from tissue of individual larvae was developed to test for population heterogeneity in ribosomal gene structure. Heterogeneity was observed in the ribosomal genes of three Ore R lines, four other D. melanogaster strains and between males and females of the same strain.     

Endogenous surface phosphorylation reactions and ectokinase activity in the guinea pig T lymphocyte

The guinea pig T lymphocyte, known to interact with other cells via direct cell-to-cell contact, exhibits endogenous surface kinase activity as reflected by the appearance of four major labeled bands in autoradiographs of dried sodium dodecyl sulfate (NaDoSO4)-polyacrylamide gel electrophoresis gels when intact cells are briefly exposed to micromolar concentrations of [gamma-32P]ATP followed immediately by solubilization with NaDoSO4 to terminate the reaction. This pattern differs from the labeling of intracellular components which is seen when intact cells are incubated with 32PO4 to generate intracellular [gamma-32P]ATP when only two major labeled bands of protein with different molecular weights are seen. Of a number of modulators of lymphocyte function tested, cyclic GMP and phytohemagglutinin (PHA) caused additional bands to appear in cells exposed to [gamma-32P]ATP. The labeling of added casein was catalyzed by intact cells harvested 4 weeks after injection of animals with Freund's complete adjuvant but not earlier. These findings indicate that plasma membrane kinase activity of guinea pig T lymphocytes is accessible to the extracellular environs (ectokinase activity) and to endogenous surface substrates and that the limitation for such reactions is the availability of ATP in the extracellular component. In view of the number of circumstances under which ATP could appear outside of cells for brief periods of time, these reactions could well take place in vivo.