RESUMO
Hovering hawkmoths expend significant energy while feeding, which should select for greater feeding efficiency. Although increased feeding efficiency has been implicitly assumed, it has never been assessed. We hypothesized that hawkmoths have proboscises specialized for gathering nectar passively. Using contact angle and capillary pressure to evaluate capillary action of the proboscis, we conducted a comparative analysis of wetting and absorption properties for 13 species of hawkmoths. We showed that all 13 species have a hydrophilic proboscis. In contradistinction, the proboscises of all other tested lepidopteran species have a wetting dichotomy with only the distal â¼10% hydrophilic. Longer proboscises are more wettable, suggesting that species of hawkmoths with long proboscises are more efficient at acquiring nectar by the proboscis surface than are species with shorter proboscises. All hawkmoth species also show strong capillary pressure, which, together with the feeding behaviors we observed, ensures that nectar will be delivered to the food canal efficiently. The patterns we found suggest that different subfamilies of hawkmoths use different feeding strategies. Our comparative approach reveals that hawkmoths are unique among Lepidoptera and highlights the importance of considering the physical characteristics of the proboscis to understand the evolution and diversification of hawkmoths.
Assuntos
Borboletas , Manduca , Animais , Néctar de Plantas , Molhabilidade , Comportamento AlimentarRESUMO
To probe its environment, the flying insect controllably flexes, twists, and maneuvers its antennae by coupling mechanical deformations with the sensory output. We question how the materials properties of insect antennae could influence their performance. A comparative study was conducted on four hawkmoth species: Manduca sexta, Ceratomia catalpae, Manduca quinquemaculata, and Xylophanes tersa. The morphology of the antennae of three hawkmoths that hover while feeding and one putatively non-nectar-feeding hawkmoth (Ceratomia catalpa) do not fundamentally differ, and all the antennae are comb-like (i.e., pectinate), markedly in males but weakly in females. Applying different weights to the free end of extracted cantilevered antennae, we discovered anisotropy in flexural rigidity when the antenna is forced to bend dorsally versus ventrally. The flexural rigidity of male antennae was less than that of females. Compared with the hawkmoths that hover while feeding, Ceratomia catalpae has almost two orders of magnitude lower flexural rigidity. Tensile tests showed that the stiffness of male and female antennae is almost the same. Therefore, the differences in flexural rigidity are explained by the distinct shapes of the antennal pectination. Like bristles in a comb, the pectinations provide extra rigidity to the antenna. We discuss the biological implications of these discoveries in relation to the flight habits of hawkmoths. Flexural anisotropy of antennae is expected in other groups of insects, but the targeted outcome may differ. Our work offers promising new applications of shaped fibers as mechanical sensors. STATEMENT OF SIGNIFICANCE: Insect antennae are blood-filled, segmented fibers with muscles in the two basal segments. The long terminal segment is muscle-free but can be flexed. Our comparative analysis of mechanical properties of hawkmoth antennae revealed a new feature: antenna resistance to bending depends on the bending direction. Our discovery replaces the conventional textbook scenario considering hawkmoth antennae as rigid rods. We showed that the pectinate antennae of hawkmoths behave as a comb in which the bristles resist bending when they come together. This anisotropy of flexural resistance offers a new mode of environmental sensing that has never been explored. The principles we found apply to other insects with non-axisymmetric antennae. Our work offers new applications for shaped fibers that could be designed to sense the flows.
Assuntos
Antenas de Artrópodes , Animais , Feminino , Masculino , Antenas de Artrópodes/fisiologia , Mariposas/fisiologia , Manduca/fisiologia , Fenômenos Biomecânicos , Resistência à TraçãoRESUMO
Summary: Central diabetes insipidus (DI) is characterized by decreased release of antidiuretic hormone, resulting in a variable degree of polyuria. The etiologies are variable, with the vast majority of cases either being idiopathic or resulting from primary or secondary tumors. Such tumors include craniopharyngioma, Langerhans cell histiocytosis, or a variety of inflammatory, vascular, or granulomatous diseases. It is exceptionally rare for pituitary adenomas to present with DI. We describe a young patient who first presented with symptoms consistent with DI. He was tested for DI and found to have panhypopituitarism due to a metastatic pineal germ cell tumor causing thickening of his pituitary stalk. Learning points: New onset central diabetes insipidus requires dedicated pituitary MRI for determination of etiology. Germ cell tumors in the pineal and suprasellar regions most commonly cause central diabetes insipidus. Determining the etiology of new-onset central diabetes insipidus can radically affect treatment.
RESUMO
Not required for Clinical Vignette.
Assuntos
Antineoplásicos/efeitos adversos , Cisplatino/efeitos adversos , Deficiência de Magnésio/induzido quimicamente , Deficiência de Magnésio/prevenção & controle , Glândulas Paratireoides/fisiopatologia , Idoso , Humanos , Hipoparatireoidismo/induzido quimicamente , MasculinoRESUMO
We present a case of serologically proved West Nile encephalitis. This patient had a normal MRI on admission. Given that the patient's clinical picture had worsened during her admission, a repeat MRI was performed, which demonstrated diffuse disease in the deep white matter of the brain. This is a case of West Nice encephalitis presenting as a disease of deep white matter that developed over a two-week span.
RESUMO
Since its introduction in New York City in 1999, the virus has spread throughout the entire North American continent and continues to spread into Central and Latin America. Our report discusses the signs and symptoms, diagnostics, and treatment of West Nile disease. It is important to recognize the disease quickly and initiate appropriate treatment. We present three cases of West Nile encephalitis at White Memorial Medical Center in East Los Angeles that occurred over the span of eight days. All three patients live within four to six miles from the hospital and do not live or work in an environment favorable to mosquitoes including shallow bodies of standing water, abandoned tires, or mud ruts. All the patients were Hispanic. Physicians and other health care providers should consider West Nile infection in the differential diagnosis of causes of aseptic meningitis and encephalitis, obtain appropriate laboratory studies, and promptly report cases to public health authorities. State governments should establish abatement programs that will eliminate sources that allow for mosquito reproduction and harboring. The public needs to be given resources that educate them on what entails the disease caused by the West Nile virus, what the symptoms are, and, most importantly, what they can do to prevent themselves from becoming infected.
RESUMO
UNLABELLED: Radioiodine ((131)I) is a critical component in the treatment of differentiated thyroid cancer. We recently saw a patient with thyroid cancer who was hesitant to take (131)I treatment because he had previously encountered an allergic reaction to administration of iodine-containing radiocontrast agent for computed tomography (CT) scanning. We were able to administer (131)I treatment after discussion that his anaphylactic reaction was not due to iodine and that radioiodine ((131)I) treatment is unlikely to cause a reaction in the patient. LEARNING POINTS: An allergy to iodine itself does not exist.When patients claim that they have an 'iodine allergy', ask them what substances they are allergic to and what kind of reaction occurred during use of such substances.Radioactive iodine is not a contraindication for patients who claim an 'allergy to iodine'.