The Challenges of Inferring Organic Function from Structure and Its Emulation in Biomechanics and Biomimetics

The discipline called biomimetics attempts to create synthetic systems that model the behavior and functions of biological systems. At a very basic level, this approach incorporates a philosophy grounded in modeling either the behavior or properties of organic systems based on inferences of structure–function relationships. This approach has achieved extraordinary scientific accomplishments, both in fabricating new materials and structures. However, it is also prone to misstep because (1) many organic structures are multifunctional that have reconciled conflicting individual functional demands (rather than maximize the performance of any one task) over evolutionary time, and (2) some structures are ancillary or entirely superfluous to the functions their associated systems perform. The important point is that we must typically infer function from structure, and that is not always easy to do even when behavioral characteristics are available (e.g., the delivery of venom by the fangs of a snake, or cytoplasmic toxins by the leaf hairs of the stinging nettle). Here, we discuss both of these potential pitfalls by comparing and contrasting how engineered and organic systems are operationally analyzed. We also address the challenges that emerge when an organic system is modeled and suggest a few methods to evaluate the validity of models in general.

Influence of spray formulation surface tension on spray droplet adhesion and shatter on hairy leaves

An empirical spray droplet adhesion model developed to predict the adhesion of spray formulations to nonhairy leaf surfaces based on their specific wettability has previously been improved to allow predictions to hairy leaves since it had been discovered that leaf hairs cause a significant consistent increase in droplet shatter compared to nonhairy leaves (superhairy leaves demonstrate distinctly different adhesion behaviour) The current study investigated the effect of spray formulation surface tension on droplet adhesion to hairy leaf surfaces The amount of shatter on hairy leaves was found to increase with decreasing surface tension The relationship derived improved the adhesion model This enables the model to better predict the effect of spray formulation on spray droplet adhesion of hairy leaf species

Development, survivorship and reproduction of Eretmocerus sp. nr furuhashii (Hymenoptera: Aphelinidae) parasitizing Bemisia tabaci (Hemiptera: Aleyrodidae) on glabrous and non-glabrous host plants

The developmental, survivorship and reproductive biology of Eretmocerus sp. nr furuhashii Rose & Zolnerowich parasitizing Bemisia tabaci (Gennadius) biotype B on tomato, cucumber, eggplant and collard at 26±0.5°C was studied. The mean longevity ranged from 6.5 days on tomato to 8.1 days on collard. The mean lifetime fecundities on tomato, cucumber, eggplant and collard were 35.4, 37.3, 41.4 and 46.4 eggs, whereas the mean lifetime fertility was 20.2, 22.7, 28.3 and 33.6 offspring, respectively. Developmental time was longest on cucumber (17.1 days) and shortest on collard (15.9 days). Survival rates varied significantly across host plants. Sex ratio (♀:♂) varied from 1.71 to 1.93 across the four hosts. The intrinsic rate of increase (rm) was highest (0.157) on collard and lowest on tomato (0.133). Mean generation time (R0) ranged from 14.7 to 20.9 days. All the data demonstrated that the reproductive success and overall performance of E. sp. nr furuhashii increased as the density of leaf hairs declined. As leaf hairs play a key role in determining efficacy, it is unlikely that effective biological control of B. tabaci using E. sp. nr furuhashii will be achieved on non-glabrous crop varieties.

Inheritance of some morphological traits in hybridization of grapevine cultivars Drenak crveni and Afuz-ali

The variability and mode of inheritance of young shoot tip, leaf, grape and berry morphological characteristics were investigated in F1 generation obtained by crossing of Drenak crveni and Afuz-ali. Based on seedlings description, considering investigated characteristics, grouping was done by applying O.I.V. method. The conclusions about inheritance of characteristics were obtained based on results of Hi2 test. The consider able variability was expressed in hybrid population. For properties of leaf characteristics (largeness, shape, dividity, and incisions), exception from typical monogenic ratio was determined. The monohybrid inheritance was determined in density of leaf hairs and downs. The monohybrid mode of inheritance was not confirmed in grape characteristics (largeness, compactness and stem length) and berry characteristics (largeness, shape and taste), while skin color is monogenic property.

Trichome morphogenesis: a cell–cycle perspective

Arabidopsis leaf hairs (trichomes) are polyploid epidermal cells with a predictable branching pattern. More than 15 genes have been identified that are involved in the regulation of branching. The cloning of the ZWICHEL , ANGUSTIFOLIA and STICHEL genes points to two mechanistic aspects of branch formation: (i) a role of the microtubule cytoskeleton; and (ii) a link to the regulation of cell divisions. The latter aspect is supported by the recent identification of an Arabidopsis mutant with multicellular trichomes, the siamese mutant, suggesting that Arabidopsis trichomes are evolutionarily derived from multicellular forms. We speculate that the spatial information for branch formation is derived from mechanisms employed in cell divisions.