Cryptic coloration and choice of escape microhabitats by grasshoppers (Orthoptera: Acrididae)

Cryptic coloration is found in many Orthoptera, especially in Acrididae, showing a great variety of forms. In a grasshopper assemblage in southeastern Brazil, preferences for escape places were detected; grasshoppers tended to escape to backgrounds in which they seem to be more cryptic. Coloration was measured using the Simpson diversity index, to quantify 'aspect diversity' (diversity of colours and shapes of patches along the insect's body). A weak positive correlation was found between grasshoppers' aspect diversity and diversification in use of escape places (use of many backgrounds to escape). Grasshoppers with similar colour patterns tended to use the same structures (leaves, sandy soil, stones) to escape.     

Angiogenesis in bronchial circulatory system after unilateral pulmonary artery obstruction

Charan, Nirmal B., and Paula Carvalho. Angiogenesis inbronchial circulatory system after unilateral pulmonary artery obstruction. J. Appl. Physiol. 82(1):284-291, 1997.We studied the effects of left pulmonary artery(LPA) ligation on the bronchial circulatory system (BCS) by using asheep model. LPA was ligated in the newborn lambs soon after birth(n = 8), and when the sheep were ~3yr of age anatomic studies revealed marked angiogenesis in BCS.Bronchial blood flow and cardiac output were studied by placing flowprobes around the bronchial and pulmonary arteries in four adult sheep.After LPA ligation, bronchial blood flow increased from 35 ± 6 to134 ± 42 ml/min in ~3 wk (P < 0.05). We also studied gas-exchange functions of BCS ~3 yr after the ligation of LPA in newborn lambs (n = 4) and used a control group (n = 12)in which LPA was ligated acutely. In the left lung,O₂ uptake after acute ligation was16 ± 3 ml/min and was similar to the chronic model, whereasCO₂ output in the control group was 27 ± 3 ml/min compared with 79 ± 12 ml/min in the chronic preparation (P < 0.05).We conclude that LPA ligation causes marked angiogenesis in BCS that iscapable of performing some gas-exchange functions.

     

Nitric oxide and beta -adrenergic agonist-induced bronchial arterial vasodilation

Charan, Nirmal B., Shane R. Johnson, S. Lakshminarayan,William H. Thompson, and Paula Carvalho. Nitric oxide and-adrenergic agonist-induced bronchial arterial vasodilation.J. Appl. Physiol. 82(2): 686-692, 1997.In anesthetized sheep, we measured bronchial blood flow(br) by an ultrasonic flow probe to investigate the interaction between inhaled nitric oxide (NO; 100 parts/million) givenfor 5 min and 5 ml of aerosolized isoetharine (1.49 × 10² M concentration).NO and isoetharine increased br from 26.5 ± 6.5 to 39.1 (SE) ± 10.6 and 39.7 ± 10.7 ml/min,respectively (n = 5).Administration of NO immediately after isoetharine further increasedbr to 57.3 ± 15.1 ml/min. NO synthase inhibitorN-nitro-L-arginine methyl esterhydrochloride (L-NAME; 30 mg/kg, in 20 ml salinegiven iv) decreased br to 14.6 ± 2.6 ml/min. NO given three times alternately with isoetharine progressively increased br from 14.6 ± 2.6 to 74.3 ± 17.0 ml/min, suggesting that NO and isoetharine potentiatevasodilator effects of each other. In three other sheep, afterL-NAME, three sequential doses of isoetharine increased br from 10.2 ± 3.4 to11.5 ± 5.7, 11.7 ± 4.7, and 13.3 ± 5.7 ml/min,respectively, indicating that effects of isoetharine are predominantlymediated through synthesis of NO. When this was followed by threesequential administrations of NO, br increased by146, 172, and 185%, respectively. Thus in the bronchial circulationthere seems to be a close interaction between adenosine3,5-cyclic monophosphate- and guanosine3,5-cyclic monophosphate-mediated vasodilatation.

     

Organogenesis in Taxus brevifolia tissue cultures

Summary A method is described for multiple shoot and plantlet formation from zygotic embryos of Taxus brevifolia. Adventitious bud primordia were best induced by culturing zygotic embryos on 1/2B5 medium supplemented with 10 M BA for 14 days. Further vegetative buds were produced following subculture to half-strength McCown's basal salt medium containing 1.0% activated charcoal. Individual adventitious shoots were excised and approximately 5% of these formed roots. Rooting frequency was increased to 58% by a single treatment with ABT rooting powder. Vigorous growing Taxus brevifolia plants were established after transfer to plant growth medium.     

Functional properties of FC-2.15, a monoclonal antibody that mediates human complement cytotoxicity against breast cancer cells

FC-2.15 is a murine IgM monoclonal antibody (mAb) that recognizes a cell-surface antigen (Ag2.15) expressed in most tumor-proliferating cells of human breast carcinomas and other neoplasias. In this study the cytotoxic ability of mAb FC-2.15, its cell-surface binding properties and endocytosis in Ag2.15-expressing (Ag2.15⁺) cells were investigated. A⁵¹Cr-release assay was used to test the FC-2.15-mediated cytotoxicity. When human serum was used as source of complement, FC-2.15 exerted a strong cytotoxic effect against human Ag2.15⁺ cells such as MCF-7 (breast cancer cell line), primary breast carcinoma cells, polymorphonuclear leukocytes and chronic myeloid leukemia cells. The mAb concentration range was 1–50 g/ml. Cytotoxicity was completely abolished when complement was inactivated. Only 3.8±2.9% of MCF-7 cells survived the treatment with FC-2.15 in the presence of human serum. A flow-cytometry assay was performed to study the Ag2.15 expression of the surviving cells and they were found to be Ag2.15^–. FC-2.15 did not mediate antibody-dependent cell cytotoxicity when different effector cells were used. Scatchard analysis with¹²⁵I-FC-2.15 on MCF-7 cells demonstrated an affinity constant of 6.9×10⁷ M^–1 and 2.8×10⁶ antigenic sites/cell.¹²⁵I-FC-2.15 was internalized to cytoplasmic vesicles reaching a maximum of 27% after 6 h incubation, followed by the release of labeled degradation products to the supernatant. FC-2.15 appears to exert its cytotoxic effect mainly in the presence of human complement, it reacts with intermediate affinity with a high-density surface antigen, and it is slowly internalized by Ag2.15⁺ cells.     

Whitening,thallus decay and fragmentation in Gracilaria chilensis associated with an endophytic amoeba

Whitening of Gracilaria chilensis, accompanied by tissue softening and thallus fragmentation, was found to be associated with the presence of an endophytic amoeba. Although the symptoms developed originally in green mutant thalli, subsequent infections in the laboratory also affected normal, wild-type G. chilensis. Ultrastructural evidence indicates that the amoebae perforate the host cell walls of both cortical and medullary cells and digest their protoplasm. Feeding by the amoeba appears to involve both phagocytosis and enzymatic digestion of the host tissue. Destruction of the host tissue resulted in large cavities first, followed by thallus fragmentation. No other organism was found during the early stages of thallus invasion by the amoeba, although bacteria may appear once the amoeba reaches the inner tissues of the host.     

Hectorella: A member of the betalain-suborderChenopodiineae of the orderCentrospermae

Roots ofHectorella caespitosa Hook. f. were induced to produce a red pigment which was shown to be a betalain and not an anthocyanin. These data indicate thatHectorella belongs to theChenopodiineae, the betalain suborder of theCentrospermae, and excludes alignment with the anthocyanin family theCaryophyllaceae.     

Caprine Arthritis-Encephalitis Virus Is Distinct from Visna and Progressive Pneumonia Viruses as Measured by Genome Sequence Homology

Competitive inhibition of hybridization between ¹²⁵I-labeled caprine arthritis-encephalitis viral RNA and homologous cDNA by heterologous viral RNA shows that the caprine retrovirus shares <20% genome sequence homology with visna and progressive pneumonia viruses. These viruses, however, are indistinguishable in immunodiffusion reactions involving the major structural protein (p28).     

Ovomucoid intervening sequences specify functional domains and generate protein polymorphism

Two thirds of the natural chicken ovomucoid gene has been sequenced, including all exons and the intron sequences surrounding all fourteen intron/ exon junctions. The junction sequences surrounding four of the introns are redundant; however, the sequences surrounding the other three introns contain no redundancies and thus the splicing sites at either end of these three introns are unambiguous. The splicing in all cases conforms to the GT-AG rule. The ovomucoid gene sequence around intron F can be used to predict the cause of an internal deletion polymorphism in the ovomucoid protein, which is an apparent error in the processing of the ovomucoid pre-mRNA. We also compare the structural organization of the ovomucoid gene with the ovomucoid protein sequence to examine theories of the evolution of ovomucoids as well as the origin of intervening sequences. This analysis suggests that the present ovomucoid gene evolved from a primordial ovomucoid gene by two separate intragenic duplications. Furthermore, sequence analyses suggest that introns were present in the primordial ovomucoid gene before birds and mammals diverged, about 300 million years ago. Finally, the positions of the introns within the ovomucoid gene support the theory that introns separate gene segments that code for functional domains of proteins and provide insight on the manner by which eucaryotic genes were constructed during the process of evolution.